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Your source for information on the 7x10, 7x12, 7x14 and 7x16 mini-lathes

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Copyright 2000-2014 by Frank J. Hoose, Jr. Home

 (10-24-13) Project: DRO PROS DROs Installation 

(Updated 06-26-13) Product Review: Sieg C8 11x30 Lathe 

Measure carefully - it's easier to remove metal than to put it back
There's always one more source of error...

Metal-workers have mettle

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If you have not already done so, please read the Disclaimer (last updated 10/18/09)

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Mini-lathe.com is an extensive information resource for the 7x10, 7x12, 7x14 and 7x16 mini lathes. This site is intended primarily to help new and prospective owners understand the capabilities, limitations and frustrations of these tools and how to modify and fine-tune them to get results you might expect only from a much more expensive lathe.

During the years since I began this site in 2000, I have also used and written reviews on some larger lathes and related equipment. See the Reviews page for much more info. Check out Mini-mill.com for information on the small milling machines that make an ideal companion to the mini-lathe.

"Ol' Stubby"

Sold by a number of vendors for around $500 to $800, these versatile and inexpensive machines are a good choice for model makers, experimenters, inventors and just about anyone else who is interested in metalworking or has a need to fabricate small precision parts. These lathes are miniature versions of industrial metal-working lathes and are quite different in design and use than wood-working lathes, but they can certainly be used for shaping wood, plastics and other materials, especially if very accurate dimensions are required.  If you follow the links on the navigation bars above, you will find a great deal of information about these lathes and related topics.

The designations 7x10, 7x12, 7x14 and 7x16 refer to the maximum diameter and length (in inches) of a workpiece that the lathe can work on. All four lathes can rotate a 7" diameter workpiece up to approximately 10, 12, 14 or 16 inches long, depending on the model. In practice though, the workpieces usually are limited to 4" diameter or less, due to various factors described throughout this site. It is possible to machine the ends of shafts longer than the lathe if the diameter is 3/4" or less so that it will pass through the hollow lathe spindle.

Fundamentally, a lathe is used to make components such as shafts and bushings that are basically cylindrical in shape. While that may not seem like much, the fact is that nearly all mechanical and engineering devices rely on components made on a lathe. So if you have interests such as RC cars, planes, boats or helicopters; robotics, atronomy, microscopy, horology are an inventor or just like to repair cars, motorcycles, household fixtures and appliances, a lathe is a great tool to have. Lathes are also used by artisans to make beads, bangles and other items for jewelry.

If you have never run a metal lathe before, or it's been many years since you last did in your high school shop class (back when high schools still had shop class!),  you can find some helpful information on the Introduction, Getting Started, Operations, Tool Grinding and Adjustments pages. Be sure to read the Safety page for important safety tips.

The mini-lathe has a lot of potential but has some shortcomings that you should be aware of before you decide to buy one - see the Reviews for more information on specific models.  Fortunately, there is now a great deal of information available about this lathe on the internet, so you are not on your own if you encounter a problem, and LittleMachineShop.com has become well established as the place to go for parts and accessories in the U.S.

I'm happy to report that the quality of these lathes has steadily been improving. Back in 2000, when I started this site, the variable speed motor controllers had a high failure rate, but the newer ones are much more reliable. Similarly, the overall quality of worksmanship is better on the newer lathes. While you still may find some minor defects, nearly all of them are now ready to use out of the box after cleaning off the packing grease and performing some minor setup and adjustments. See theGetting Started page for details.

If you are considering purchasing one, the Product Review pages will give you some detailed comparisons among various models. You may also find my thoughts onWhich Lathe to Buy helpful in making your decision.

The great majority of mini-lathes sold in the U.S. and worldwide are made by Sieg in Shanghai, China. They are re-branded by several vendors, painted in a variety of colors and sold with various combinations of accessories and with four bed lengths: 8", 12", 14" and 16", but all are basically the same lathe (Well, ok, the Micro-Mark version is kinda unique...).  A very similar lathe, made by Real Bull in China, makes up the rest of the market.

While this site focuses mainly on the Chinese mini-lathes, be sure to check out the slightly smaller, but very capable and high-quality lathes made in the U.S. by Taigand Sherline; they're very popular among precision model makers.

When I began this site, I was using the 7x10 version of the mini-lathe, shown above. While the 7x10's are still available, the 7x12 is  more common nowdays, and for good reason: it's actually 4" longer than the 7x10 (a result of overly optimistic marketing of the 7x10; which is really only 7x8).   Since the mini-lathe is now available in four lengths (8", 12", 14" and 16"), you will find references to all four models throughout this site. Most of the features and capabilities are very similar, other than the maximum working length. You may also see references to "7x" lathes where I am referring to all four sizes generically.

Specific features of these lathes are continually being improved by the manufacturer. Therefore, some of the older information on this site may no longer be relevant. For example, the lathes made before 2000 had a somewhat crude motor speed control with a minimum speed of about 100 RPM. The motor speed controls have been continually improved since then and the newer ones are much more sophisticated and reliable than the the very early ones.

Beginning around 2007, Sieg introduced the "S" series of machines which have brushless DC motors. These new motors have much more torque than the prior motors, so that the internal HI-LO range gears are no longer needed. The result is a quieter, more powerful and more reliable machine. The newer lathes also include some improved safety features over the older ones.

One of the best sources of information on the mini lathe and related topics has been the Yahoo group 7x10minilathe, a very knowledgeable and experienced group of guys who are always ready to welcome and help newcomers. Discussions are by no means limited to the 7x lathes so feel free to ask any question even remotely related to machining and you will get plenty of good advice. Unfortunately, at times over the years since the group began in 1999, the subject matter has degenerated into political harangues, making it much less approachable for the new mini lathe owner. A spinoff Yahoo group, 7x12minilathe, with more closely monitored content, also is an excellent source of information. You'll need to join the group to participate. There also are Yahoo groups that focus on specific mini lathe interests such ashorology (clock-making), modifications, and little engines.

For discussion en Espa�l visit this group:  http://foro.metalaficion.com

Check the Home Shops links on my Links page and you will find lots of great tips from other mini lathe owners.

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Mini Lathe Introduction

You are visitor number  since 07/04/02
Copyright 2000-2013 by Frank J. Hoose, Jr. Home

Mini-Lathe    Mini-Mill    Bandsaw   Grinder  Anodizing   Lapping    Links   Projects   Safety     Premium Content

Mini-lathe:  Accessories   Adjustments   Capabilities    Chucks    Dial Indicators   Features   Getting Started   Glossary     Introduction   Materials    Modifications   My Shop   Operation    Reviews    Sieg Factory    Tool Grinding    Troubleshooting   Tuning     Versions

Introduction:  Introduction    Terminology    Glossary

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Table of Contents

• Introduction
• Terminology
• Lathe Dimensions
• Glossary

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If you have not already done so, please read the Disclaimer (last updated 10/18/09)

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Mini Lathe - Introduction

If you are new to metalworking lathes and lathe work, this page will help you understand some of the basic concepts, terminology and capabilities. In essence, a lathe, whether for woodworking or metalworking, rotates a cylindrical workpiece along its axis and removes material from the workpiece to form it into a specific shape.

On a woodworking lathe, the cutting tools usually are hand-held against a support and are moved in and out and back and forth along the surface of the work by hand to form a shape such as a table leg.

On metalworking lathes, the cutting tools are held rigidly in a tool holder that is mounted on a movable platform called the carriage. The tool is moved in and out by means of hand wheels and back and forth either by turning a handwheel or under power from the lathe. The result is that material can be removed from the workpiece under very precise control to produce shapes that are truly precision made. Dimensional accuracies of one-one-thousandth of an inch (.001") or one-tenth of a millimeter are typical. Because of the inherent rotational nature of a lathe, the vast majority of the work produced on it is basically cylindrical in form. In spite of this, the lathe is an extremely versatile machine capable of producing a surprising variety of objects used mainly as component parts of mechanical systems.

After learning some of the basic terminology of the lathe, check out the Capabilities and Features pages for lots more information.

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Terminology

To gain a good understanding of the lathe, you will need to know the names of the various components, as illustrated below. The carriage, in the circled area, consists of the apron, the vertical  casting on which the carriage handwheel is mounted, and the saddle (not shown), the H-shaped casting that rides on the ways to which the apron is attached.

 Animation of power feed turning operation

Animation courtesy of Enric del Rey and Latheworks, also check out this lathe group, en espanol

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Lathe Dimensions

When comparing the size and working capacities of metal lathes there are several key dimensions to consider:

Swing over bed	The diameter of the largest workpiece that can be rotated on the spindle without hitting the bed. This is the first of the two numbers used to describe the size of a metal lathe. In the case of the 7x10 or 7x12 lathes, it is 7".
Distance between centers	The longest piece of work that be held between a center in the headstock and a center in the tailstock. (see glossary below for more information). This is the second of the two numbers used to describe the lathe size. Based on this you would expect that a 7x10 would accommodate 10" between centers, a 7x12, 12" and a 7x14, 14".  In fact, due to wishful marketing, the 7x10 is really only a 7x8. The 7x12 and 7x14 are what you would expect them to be.
Swing over the carriage	The diameter of the largest workpiece that can rotate over the carriage without hitting it. On the 7x lathes this is about 4"
Diameter of spindle through-hole	The diameter of the hole that passes through the spindle. On the 7x lathes (or any lathe having a #3 Morse Taper spindle) it is about 3/4". When facing relatively long stock, the free end of the stock can pass through the spindle if it is no larger than thethrough-hole diameter.

Here's a table summarizing some of the dimensions for a 7x12 and 9x20 lathe:

	7x12	9x20
Swing over bed	7"	9"
Distance between centers	12"	20"
Swing over carriage	4"	5"
Spindle Taper	#3MT	#3MT
Spindle through-hole diameter	3/4"	3/4"
Tailstock taper	#2MT	#2MT

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Glossary of Lathe and Mill Terms

Apron	Front part of the carriage assembly on which the carriage handwheel is mounted
Bed	Main supporting casting running the length of the lathe
Between Centers	1. A method of holding a workpiece by mounting it between a center in the headstock spindle and a center in the tailstock spindle (seeCenter). The workpiece is gripped and driven by a dog. 2. A dimension representing the maximum length of a workpiece that can be turned between centers. A 7x10 lathe is 10" between centers; a 7x12 lathe is 12" between centers. Since longer is generally better, lathe vendors sometimes overstate this number.
Bit	A sharpened cutting tool, such as a drill bit or lathe bit, used to remove metal or other material from a workpiece
Carbide	An extremely hard, heat- and wear-resistant material used for making cutting tools. In the context of machine tools, usually refers to tungsten carbide. While very hard, it is brittle and subject to chipping under impact.
Carriage	Assembly that moves the toolpost and cutting tool along the ways
Carriage Handwheel	A wheel with a handle used to move the carriage by hand by means of a rack and pinion drive
Carriage Lock	A mechanism for locking the carriage to the ways so that the saddle does not move along the ways during facing operations. A standard feature on most larger lathes, but not on the mini lathe. Easy to add, though.
Casting	A metal component formed into a specific shape by pouring molten metal into a hollow form of the desired shape. After the metal cools and solidifies, the shaped casting is removed from the form and excess metal, known as flashing, is removed. The form typically is made from a specialized mixture of sand and binding agent and is divided into two halves that are separated to remove the finished casting.  May also refer to the process of producing a casting. The casting process is used to manufacture most of the large metal components of machine tools. The rough cast components are machined by machine tools to form precision mating surfaces such as the ways of a lathe or the table of a milling machine.
Center	A precision ground tapered cylinder with a 60� pointed tip and a Morse Taper shaft. Held in the lathe tailstock to support the end of a long workpiece. May also be used in the headstock spindle to support work between centers at both ends. Also the process of positioning a workpiece accurately in line with a drill or mill. A live center is a center with integral bearings to reduce friction; a dead center has no bearings, so the tip must be kept lubricated to keep the center and workpiece from overheating due to friction. verb: To accurately position a workpiece so that the center of the workpiece, or the center of a feature such as a hole, is concentric with a the lathe centerline or the spindle of a milling machine. May also apply to centering a rotary table or other work holding device concentric with the milling machine spindle.
Center Drill	1. A short, stubby drill used to form a pilot hole for drilling and a shallow countersunk hole for mounting the end of a workpiece on a center.  2. The process of drilling a workpiece with a center drill
Centerline	An imaginary line extending from the center of the spindle through the center of the tailstock ram, representing the central axis of the lathe around which the work rotates.
Chuck	A clamping device for holding work in the lathe or for holding drills in the tailstock. Drill chucks are sometimes referred to as Jacobs Chucks, a brand name that popularized that style of chuck.
Compound	Movable platform on which the toolpost is mounted; can be set at an angle to the workpiece. Also known as the compound slide and compound rest.
Compound Handwheel	A wheel with a handle used to move the compound slide in and out. Also known as the compound feed.
Counterbore	1. To drill a shallow flat-bottomed hole slightly larger than and concentric with a previously drilled hole to allow the head of a screw to be sunk below the surface of a workpiece.  A special counterbore tool or an end mill is used to drill the hole so that the bottom will be flat. 2. A hole drilled by this process.
Countersink	1. To form a shallow, cone-shaped hole surrounding a smaller diameter drilled hole. A countersink is often used so that the head of a flat-head screw will be flush with, or slightly below, the surface in which the screw is being used. 2. A cutting tool, similar to a drill bit, with a cone-shaped tip, used to cut a countersink hole. Often combined with a short drill bit tip as a "combination drill and countersink", or center drill.
Cross Feed	A handwheel or crank that moves the cross-slide by turning a screw. Also the action of moving the cross slide using the cross feed handwheel.
Cross Slide	Platform that moves perpendicular to the lathe axis under control of the cross-slide handwheel
Cross-slide Handwheel	A wheel with a handle used to move the cross-slide in and out. Also known as the cross feed.
Cutting Tool	The tool that does the cutting, or removal of metal or other material. May refer to any type of cutting tool such as a drill, reamer or a lathe bit. A lathe bit typically has a square cross-section with a sharpened tip on one end. It is made from very hard and heat-resistant material such as High Speed Steel or a form of carbide.
Dead Center	A lathe center made from a solid piece of steel with no bearings, typically used to support the tailstock end of a relatively long, limber workpiece. Since there are no bearings, the tip must be well lubricated to keep it from heating up due to friction. See also: Live Center.
Dog	Also known as a Lathe Dog or Dogleg. An "L"-shaped adapter, usually made of cast iron,  with a hole for the workpiece and locking screw to secure the workpiece. Used to clamp a workpiece and apply rotational force to it while the workpiece is mounted between centers along with a faceplate. The dog engages with a hole in the faceplate to apply the force to the workpiece. Used in place of a chuck, especially in pre-1940's work, and/or when tapers are cut by offsetting the tailstock.
Dovetail or Dovetail Slide	A sliding surface between two closely matched components on a machine tool such as a lathe cross-slide. The dovetail ensures that the two components can move in a precise linear motion with very little side-to-side motion. So-named because it looks, in an end-on view, similar to the shape of a dove's tail.  Also a common type of joint used in woodworking and so-named for the same reason.
Faceplate	A metal plate with a flat face that is mounted on the lathe spindle to hold irregularly shaped work.
Facing	A lathe operation in which metal is removed from the end of workpiece to create a smooth perpendicular surface, or face. The cutting tool is moved across the ways by turning the cross-slide handwheel, aka cross-feed.
Gib	A length of steel or brass with a diamond-shaped cross-section that engages with one side of a dovetail and can be adjusted by means of screws to take up any slack in the dovetail slide. Used to adjust the dovetail for optimum tightness and to compensate for wear.
Halfnut or Half-nut	A nut formed from two halves which clamp around the leadscrew under control of the halfnut lever to move the carriage under power driven from the leadscrew. The halfnut commonly is 6-10 full threads in length to spread the driving force over a larger area.
Halfnut Lever	Lever to engage the carriage with the leadscrew to move the carriage under power
Handwheel	A wheel turned by hand to move a component of a lathe or other machine tool. Often will have a handle extending from the front face. The handle facilitates rapid turning of the handwheel.
Headroom	The distance between the tip of the spindle (or chuck) and the table on a milling machine or drill press.
Headstock	The main casting mounted on the left end of the bed, in which the spindle is mounted. Houses the spindle speed change gears.
High Speed Steel(HSS)	An alloy of steel used for cutting tools such as lathe bits and drill bits. HSS is highly-resistant to losing its hardness due to heating from friction. When used for lathe cutting bits,  a HSS blank is ground to the desired shape on a bench grinder.
Interrupted Cut	A cutting operation on a lathe or mill in which the surface along which the cutting tool is moving has gaps or openings. The cutting action of the tool is thus "interrupted" each time it passes over such an opening. Due to the vibration caused by this process, extra care must be taken to ensure that the cutting tool and the workpiece are securely mounted so that they don't work loose. On a milling machine, the head must be securely locked in place so that it does not slip.
Jacobs Chuck	A common style of drill chuck that uses a geared outer ring along with a chuck key that engages with the geared ring to hold a drill bit very tightly. Prior to the introducion of "keyless" chucks, these were universally used on handheld power drills and drill presses. Jacobs is a trademarked brand name that is often used as a generic name for chucks of that style.
Jacobs Taper	One of several industry-standard specifications for tapered tool shanks. Tapered shafts on tools engage with a recess of matching taper in a lathe, drill press, milling machine spindle or on a rotary table or similar tools. Tapers are precision-machined and when properly mated, and free from oil and grit, hold the tool tightly and concentric to the machine spindle. Once mated, tools held by a taper must be removed by forcing them free by driving a soft shaft in from the rear of the tool, using a hammer or screw to apply force.
Leadscrew	Precision screw that runs the length of the bed. Used to drive the carriage under power for turning and thread cutting operations. Smaller leadscrews are used within the cross-slide and compound to move those parts by precise amounts. Industrial lathes have a separate drive for power feed and reserve the leadscrew for screw cutting to reduce unnecessary wear on the leadscrew.
Live Center	A lathe center with integral ball bearings that allow the tip to turn independently of the tapered end to reduce friction when using the center to support the end of the workpiece. See Dead Center.
Long Taper	A taper, cut on a lathe, that typically is too long to cut by offsetting the compound. On many lathes, the tailstock is formed from two components, the upper part of which can be offset relative to the lathe centerline. The workpiece is center-drilled on both ends and supported between centers using a dog to drive the workpiece. The tailstock is offset to the desired angle of the taper. As the carriage moves along the ways, the cutting tool remains parallel to the lathe centerline, but the workpiece is cut along a taper because it is offset. Industrial-class lathes sometimes have a taper attachment that allows for cutting long tapers without offsetting the tailstock. As the carriage moves along the ways, the taper attachment moves the cross-slide in or out at a constant rate, resulting in a tapered cut.
Machine Tool	A machine, such as a lathe, drill press or milling machine, designed to shape and form metal and other materials to a high degree of precision. Typical dimensional accuracies are on the order of thousandths of an inch or hundredths of a millimeter. Machine tools can range from desk-top size to huge machines weighing many tons used for industrial work.
Machining	The process of shaping metal or other material using a machine tool such as a lathe or milling machine. Most machining operations, such as drilling or turning, cut away excess material leaving the desired shape and dimensions.
Morse Taper	A taper of specific dimensions used to mate matching male and female parts such that they lock together tightly and concentrically. Tapers are of various sizes such as #0, #1, #2, #3, etc. with larger numbers representing larger sizes. The spindle of the mini-lathe has a #3 Morse Taper and the tailstock ram has a #2 Morse Taper.
Pilot Hole	A shallow hole, usually cone-shaped, drilled as a starter hole before drilling a deeper hole. The pilot hole helps to ensure that the drill bit enters the material at the desired location and does not drift or wander as the bit starts cutting into the material being drilled.
Quill	Part of a drill press, milling machine, lathe tailstock or other machine tool that extends from and retracts into a part of the machine under control of a hand lever or handwheel. Typically, the quill has an industry-standard taper to hold a chuck or other tool-holding device.
R8 Taper	An industry-standard taper most often used for the the spindle bore and tooling shanks of mid-sized milling machines. Tapered shanks ensure that machine tools are accurately concentric with the spindle and resist the sidewards forces imposed by milling operations. R8 tapers are considered to be "self-releasing", needing little or no force to break them free from the spindle when changing tools.
Rack and Pinion	A gear arrangement for moving a linear gear (rack) by turning a circular gear (pinion). Used to convert a rotating motion, typically of a handwheel, into a controlled linear motion. A typical example is the focusing mechanism on a microscope.
Saddle	A casting, often shaped like an "H" when viewed from above, that rides along the ways. Along with the apron, it is one of the two main components that make up the carriage.
Short Taper	A taper, cut on a lathe, which is sufficiently short in length that it can be cut by offsetting the compound to the desired angle of the taper.
Shoulder	The point at which a workpiece changes sharply from one diameter to another.
Spindle	Main rotating shaft on which the chuck or other work-holding device is mounted. It is mounted in precision bearings and passes through theheadstock. In more general terms, the main rotating part of a machine tool.
Spindle Through-hole	A dimension indicating the minimum diameter of the hole that passes through the spindle. A workpiece with a diameter smaller than this can pass through the spindle to facilitate working on long pieces of work. On the minilathe it is 3/4" but can safely be reamed out to 13/16". Note that near the front of the spindle the hole is tapered, to hold tapered tooling, and is larger than 3/4" when looking at the spindle.
Stock	1. The piece of metal or other material being machined in a lathe 2. Raw material such as metal rod that will be cut down to workable size and machined
Swing	A dimension representing the largest diameter workpiece that a lathe can rotate. The 7x10, 7x12 and 7x14  mini-lathes all have a 7" swing, meaning that the maximum size workpiece that can rotate without hitting the bed is 7" in diameter. A related dimension, Swing Over Carriage or Swing Over Cross Slide, is the maximum diameter workpiece that can rotate over the cross slide. This is about 4" on the 7x lathes, so any workpiece longer than about 3" cannot be larger than 4" diameter.
Tailstock	Cast iron assembly at the right end of a lathe that can slide along the ways and be locked in place. Used to hold long work in place or to mount a drill chuck for drilling into the end of the work.
Tailstock Handwheel	A wheel with a handle used to move the tailstock ram in and out of the tailstock casting.
Tailstock Ram	A piston-like shaft that can be moved in and out of the tailstock by turning the tailstock handwheel. Also known as the quill. Has a tapered internal bore to accept a Morse Taper shank. The shaft, or ram, is advanced or withdrawn by rotating the tailstock handwheel located on the right end of the tailstock. The ram usually is marked in inches and/or millimeters and can be locked in place at a specific point by a locking lever.
Taper	1. An even, gradual change in the diameter of a workpiece.  2. The process of cutting a workpiece to produce a tapered diameter. 3. A tapered section of a workpiece cut on a lathe 4. The tapered end of a tool or spindle that conforms to an industry-standard pattern such as a Morse Taper , Jacobs Taper or R8 Taper.
Through-hole	The hole that passes through the spindle. Rods that are smaller in diameter than the through-hole can extend through the hole, thus making it possible to machine the ends of a rod that otherwise would be too long for the lathe.
Tool	A cutting tool used to remove metal from a workpiece; usually made of High Speed Steel or carbide.
Tool Blank	A piece of High Speed Steel from which a cutting tool is ground on a bench grinder. Typically 5/16" square by 2 1/2" long for mini-lathe use.
Toolpost	A holding device mounted on the compound  into which the cutting tool is clamped
Turning	A lathe operation in which metal is removed from the outside diameter of the workpiece, thus reducing its diameter to a desired size.
Ways	Precision ground surfaces along the top of the bed on which the saddle rides. The ways are precisely aligned with the centerline of the lathe.
Work or Workpiece	Material being held in the lathe for a machining operation. Typically a rod or cylinder of metal or plastic but could also be a more complex shape such as a casting for a model airplane motor.

Mini Lathe Features

Page 1 of 2

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Click on components of the lathe in the photo to learn more about them...

This page describes the construction and features of the 7x10 mini lathe.  The specific model described is the Harbor Freight 7x10, but most of the information applies to similar lathes sold by other vendors including Enco, Micro-Mark, Northern Tool, Homier, Grizzly and others.  See the Versions page for lots more info on the various models available. There are differences in the power supplies and other features.   Newer or older models may also differ in some respects from the specific model described here.

This little lathe has a lot of potential but has some shortcomings that you should be aware of before you decide to buy one, as you will learn in the following sections. Fortunately, there is now a great deal of information available on this lathe on the web, so you are not on your own if you encounter a problem.  One of the best sources of information is the 7x10 interest group.

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If you have not already done so, please read the Disclaimer (last updated 10/18/09)

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Table of Contents

• Disclaimer
• Minilathe Introduction
• Terminology
• General Construction
• Headstock and Control Levers
• Spindle and Chuck
• Motor and Electronics
• Bed and Ways
• Carriage and Saddle
• Cross-slide and Compound
• Toolpost and Tools
• Lead Screw and Power Feed
• Half Nut and Threading Dial
• Cutting Screw Threads
• Change Gears and Tumbler Gears
• Tailstock and Drill Chuck

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The 7x10 Mini Lathe - Introduction

Having owned an Emco Maximat lathe/mill in the seventies and having a little more spare time now that my kids are grown, I was in the market for a small lathe in Fall of 1999. After searching the web and looking at various options, I purchased the Harbor Freight 7x10 mini lathe. It is sold under the Central Machinery brand name and is Harbor Freight SKU# 33684.

This lathe is made in China, and has a lot of rough edges (literally and figuratively) out of the box. However, most of its flaws are fixable and if you spend some time improving it, you can end up with a very capable and reasonably precise little lathe. This is a very sound approach if you need a lathe with more beef than the high-quality US-made Sherline or Taig micro-lathes, but can't afford or justify spending $1500 or more for a high-quality minilathe such as the Prazi, Sakai or Emco.  (Note 02/20/02 the Sakai company went out of business recently and these lathes are no longer manufactured).

If you need a precise and dependable tool right out of the box, this is probably not the right lathe for you. Update (09/12/02) This was true of my first 7x10, purchased in 1999. The quality of the 7x lathes seems to be steadily improving based on ones that I have bought since then and many reports on the 7x interest group. I can now say that they are ready to go after cleaning off the packing grease and maybe making a few adjustments. It is still true, though, that you can sigificantly improve the performance by making various adjustments and modifications. End of update

Some owners have described  it as more like buying a kit of parts which you then refine into a finished working tool. Many owners, myself included, find the process of improving the lathe to be as much fun as making the other stuff which we bought it for in the first place. If you need to get right to work, or just don't want to spend your time fixing up a lathe, consider instead the excellent machines offered by Taig and Sherline.

The Harbor Freight 7x10 sells for $399 but sometimes goes on sale for $349 or even as low as $329. At that price, it is a lot of bang for the buck! It weighs about 80lbs - light enough for one person to move it easily, but heavy enough to turn some serious (by home shop standards) metal. Harbor Freight also includes free shipping and even pays return shipping if you need to return something. Other companies charge $40-50 for shipping and a heavy item may cost you another $40 if you need to return it for some reason, so this is a valuable service.

Several vendors, such as Grizzly, Micro-Mark, Enco and others now sell variations of this lathe with different features, so choosing the best model for your needs is becoming a little more complicated that it was when I bought mine.  To help you with this process see my mini-lathe versions page.

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Terminology

To gain a good understanding of the lathe, you will need to know the names of the various components, as illustrated below. The carriage, in the circled area, consists of the apron, the vertical  casting on which the carriage handwheel is mounted, and the saddle (not shown), the H-shaped casting that rides on the ways to which the apron is attached.

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General Construction

In the photo below, the carriage and tailstock have been removed to show the basic construction of the lathe. This is the 7x10 model. The 7x12, despite it's designation, is actually 4 inches longer. The bed is a single sturdy casting with cross braces. Attached to the base of the bed is a sheet metal chip tray. A sheet metal chip/splash guard runs behind chuck and along the back of the lathe. 

Varmint Al did not like these and removed them, but I find them pretty helpful in keeping chips under control.  Well, come to think of it, the chips get all over the shop anyway, and the tray does have a way of getting small bolts, taps, drills, etc. hidden under its edge.  Four rubber feet are mounted on the bottom of the lathe under the chip tray.  I removed these and bolted the lathe directly to my workbench after retapping the metric threads to 1/4-20.

Here's a view of the back of the lathe, showing the chip guard, motor cover and control levers.

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Headstock and Control Levers

The headstock comprises the rectangular metal casting at the left end of the lathe. It contains the spindle shaft and its support bearings and the Hi/Lo speed shift lever and gears. Normally, the headstock is mostly hidden behind the electronics box and the spindle is hidden by the gear cover.  In the following photo these have been removed to reveal the headstock casting and spindle shaft. Instructions for removing and lubricating the headstock can be found on the Tuning page.

On the back of the headstock are two levers

• The tumbler gear lever
• The Hi/Lo speed lever

The tumbler gear lever sets the rotation of the leadscrew which advances the carriage under power. It has three positions:

• Forward (up) -  carriage moves towards the headstock when spindle rotates forward
• Neutral (mid)
• Reverse (down) - carriage moves away from the headstock when spindle rotates forward

There is a knurled spring-loaded sleeve on the lever which must be pulled back with considerable force to move the lever from one position to another. A locking pin engages with detents in the headstock casting to hold the lever in place. This is not a very robust design and has caused minor troubles for some users when the tumbler gears did not engage or disengage fully.

Tumbler gears are an unexpected feature on such a low cost lathe.  They allow you to reverse the direction of the leadscrew relative to the direction of spindle rotation.  Note that this is not the same as merely reversing the spindle direction, which would also reverse the leadscrew rotation. The most common use of this feature is in cutting left-handed threads.

The Hi/Lo speed lever selects the spindle speed range by engaging different gear ratios within the headstock. In Lo range, the speed range is approximately 150 to 1500 RPM and in Hi range, 460 to 2900 RPM - at least that's what's marked on the speed control knob legend.

The Hi/Lo speed control lever should never be shifted when the lathe is moving and this fact is clearly marked on warning labels on the lathe.

Many 7x10 users recommend opening up the headstock and lubricating the gears and shift mechanism with white lithium grease. On mine, I was compelled to do this when the shift lever seized up after a few months of use. A good workover with grease solved the problem and made the lathe run a little quieter. Opening up the headstock is probably best left until you are comfortable with other maintenance operations on the lathe.

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Spindle and Chuck

The spindle is the main rotating shaft on which the chuck is mounted. It is supported by precision thrust bearings mounted in the headstock casting and is driven by a toothed pulley and belt which runs down to a smaller toothed pulley on the motor.

The spindle plate is 3" in diameter and has a raised lip which mates with a recess in the back of the chuck, providing precise centering of the chuck. The spindle bore is a #3 Morse Taper so you can purchase and use any standard MT3 accessories such as live or dead centers.  A nice feature of the 7x10 is that it has a relatively large through-the-spindle diameter of 3/4"; bigger than you might expect for a lathe of this size. This bore can be safely reamed to 13/16" to provide a little additional clearance.

Note that there are 6 mounting holes in the spindle. The extra mounting holes mate directly with the 3" 4-jaw chuck - a great accessory. Some older models of the 7x10 and the HF 39916 cam-lock tailstock model, are lacking these extra mounting holes.

The stock chuck is a 3" 3-jaw made in Japan. It is of excellent quality and accuracy considering the price of the lathe. Users have often reported less than .001" runout. Optional chucks can easily be added to increase the versatility of the minilathe

Here's a shot of the chuck in my hand to give you a better idea of the size:

Three 6mm studs are threaded into the back of the chuck. The chuck is mounted the lathe spindle by mating these studs with holes in the lathe spindle plate and then securing it with 3 nuts from the backside of the spindle plate. There's very little clearance behind the plate, so this is one of the more challenging setup operations on the lathe. Here are some hints on how to work around this. Before removing the chuck for the first time, you may want to make a mark on the edge of the spindle plate and a corresponding mark on the edge of the chuck. This will enable you to reinstall the chuck in the same orientation in which it came from the factory. This is not critical, but may help you gain a little extra accuracy.

Both outside and inside jaws come with the chuck. The maximum diameter you can safely hold with the inside jaws is about 1.25"; with the outside jaws it is about 2.5". This photo shows the outside jaws and the chuck key.

For maximum accuracy, it is a good idea to always mount each jaw in the same slot that it originally was in.  Before removing the jaws from the chuck the first time, assign an arbitrary number to each jaw and mark the jaw and its slot with a Sharpie pen.   After removing the jaws, look closely at the slots on the sides of the jawsand you will see that they are numbered from the factory.  Use a center punch to make 1, 2 or 3 dots on the chuck slot corresponding to the factory numbering of the jaws. When reinstalling the jaws, you must always follow the factory numbering sequence.

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Motor and Electronics

The speed control electronics are on a circuit board inside the plastic housing on which the power switches and speed control knob are mounted. A red plastic rocker switch with an integral pilot light controls the main AC power to the lathe. A metal 3-position toggle switch controls the direction of spindle rotation; the middle position cuts off power to the motor while maintaining power to the speed control circuitry.

It's good practice to use the middle position of this switch, rather than the red power switch, to stop the motor when you are working since the red power switch will induce a 'surge' to the speed control board each time it is powered on. Over time, this surge can potentially shorten the life of the electronics and cause a failure of the speed control board. Use the red power switch to power off the lathe at the end of the day.

Speed is controlled by the small black knob; this can be done while the lathe is running, which is a really nice feature. In Lo range, the speed range is approximately 150 to 1500 RPM and in Hi range, 460 to 2900 RPM.

Two modifications described on my mods page are a forward/reverse interlock switch (visible on the left side of the control box on my lathe) and a way to reduce the default motor speed for better control during tapping, centering and threading operations.  Note: (10/01) the more advanced power supply on the Grizzly 7x12 and the newer 7x10s make these mods unnecessary.

Here's a view inside the back of the speed control box. The switch on the side of the box is the forward/reverse interlock I added.

A clear plastic sheet helps to prevent metal chips from getting into the circuit board a wreaking havoc. Several owners have found, though, that this is not enough and have had the board short out. The leadscrew makes a nice little chip conveyor and passes right through the electronics box. Because of this risk, some owners have moved the electronics into separate box mounted above the headstock.

A brush-type DC motor labeled as 3/4 HP 110V powers the lathe via a continuously variable electronic speed control. This variable speed feature is one of the greatest features of the 7x10 since it allows you to adjust speed instantly, even while turning a workpiece, without the hassle of pulleys and belts used on many low cost machines.

A toothed belt conveys power from the motor shaft to the lower of two shafts in the headstock.  Gears on this shaft engage with gears on the upper spindle shaft to drive the spindle. The HI/LO lever changes the gears within the headstock to change the speed and torque of the spindle.

  

The motor's 3/4 HP rating is suspect, but the motor has adequate power and torque for all but the most demanding operations you are likely to perform on a small lathe like this. It's not hard to stall the motor, though, when making a parting cut or attempting to turn a workpiece 3" or more in diameter. If you do stall it, switch the toggle switch to the neutral position quickly to avoid blowing the power supply fuse.

Although I have stalled my lathe many times, I have never blown a fuse, but I have heard reports from others that this can happen. The fuse holder is visible just above the red power switch. The fuse is a 250V 3amp mini glass fuse which is available at Radio Shack.

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Mini Lathe Accessories

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If you have not already done so, please read the Disclaimer (last updated 10/18/09)

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Aluminum Round Stock

Aluminum is an excellent material to practice on since it is inexpensive, cuts easily and takes a nice finish. I use it for most of my projects unless there is some reason to use another material, such as the need for extra strength.

In practice, there are many varieties of aluminum. During the refining process aluminum is mixed with specific proportions of other metals to produce desired characteristics of strength, weight, corrosion resistance and machinability in the combined metal, which is called an alloy. Many different alloys are available to meet specific needs, but '6061' alloy is a good choice for working on the minilathe.

You are unlikely to find 6061 or similar alloys at your local hardware store - the kind you find there is typically very soft and gummy and does not machine well. To get the good stuff you will need to order from an industrial supplier such as Online Metals, MetalMart or Enco. A good starter supply would be 3' lengths of 1/8", 1/4", 1/2" and 3/4". Some of the online metal suppliers have kits that include a wide range of stock for about $100.

From some suppliers you must specify the length that you want, and they may charge a 'cutting fee' to cut the material to size. Other suppliers sell stock in fixed length of 2', 3' or 6'. Typically I buy aluminum in 6' lengths for diameters up to 1". Since the amount of metal in a rod increases with the square of the diameter, the price goes up steeply for larger diameters. To give you an idea, here are some prices from the 2003 Enco catalog for 6 foot lengths of 6061 round stock:

Diameter	Price (2003)	Price (2012)
1/4"	2.74	6.72
3/8"	4.26	9.42
1/2"	6.90	13.74
1"	22.20	30.11
2"	80.68	98.24

Fortunately, when working with larger diameters, the workpieces are usually relatively short, so you don't need as much.

For more information, see the Materials page.

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Ball-end Hex Wrenches (11-04-13)

These are so handy that I should have added them to this page years ago. (but I've been busy!)  I have an SAE and a metric set made by Bondhus. They are a huge convenience when trying to access a socket head cap screw where straight-line access is blocked. Usually, the screw can be loosened or tightened using the greater leverage of the long handle, then rapidly spun in or out using the ball-end. The holders for mine are beat up from years of use, but the tools are as good as the day I bought 'em.

    

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Bench Grinder

 
You will need a 6" bench grinder for grinding tool bits. I bought an Ohio Forge brand from Home Depot for under $50 and it has served me well.   See my grinder mods page for more info.

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Brass Round Stock

Brass is a nice material to work with, though somewhat expensive compared with aluminum or steel. It can add a nice touch of contrasting color to a project that will be displayed. The alloy most often used for home shop work is 360. You can obtain it from the typical  suppliers such as Online Metals, MetalMart or Enco.

For more information, see the Materials page.

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Center Drills

 
Center drills are stiff, stubby little drills used to start holes in the end of workpiece. If you try to drill a hole in a workpiece without using a center drill you will find that the drill will most likely wobble off center and not drill straight into the workpiece.

Standard drilling practice is to first make a facing cut on the end of the workpiece, then drill a starter hole using a center drill and then drill the hole to the required depth with a standard drill

Center drills come in many sizes but you will definitely need sizes #1, #2 and #3 (good idea to get 2 of each). You can buy sets of #1-#5 on sale for under $5.00

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Chip Brushes

Chip brushes are inexpensive paint brushes that are handy for all kinds of uses around the shop. I'm not sure where the name originated, but I don't think it had anything to do with removing chips; nevertheless this is one of the uses these brushes excel at. They are also ideal for use with Kerosene or WD-40 to clean the packing grease off a new lathe or mill. Incidentally, experienced machinists will tell you always to use a brush, rather than compressed air, to clean the chips from machine tools as compressed air will drive the chips deep into the recesses of the machine. Chip brushes and a shop vac are the preferred way to clean up chips.

You can get them from the usual industrial suppliers such as MSC, J&L and Enco and can usually find them at the big-box hardware stores in the paint section.  Some, such as the ones at Home Depot, have natural bristles which I like a lot better than the synthetic bristles shown in the photo above. The synthetic bristles tend to splay out over time and don't do as good a job. At about $.30 to $.60 each depending on the size, they are cheap enough that you won't feel too bad about tossing them out if they get too gunked up, but they hold up for years in most applications. Get several in each size such as 1", 2" and 3" and keep them around the shop.  You can't have too many!

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Chucking Reamers

Chucking reamers are used to make the final cut on relatively small diameter holes (typically 1/2" or less). Unlike a standard twist drill bit, a reamer will form a hole that is exactly round in cross-section and with a diameter accurate to .001".  In use, they are clamped in the tailstock chuck or a drill press chuck and advanced into the work as in a drilling operation. They are relatively expensive so it makes sense to buy them one or a few at a time as you need them.

They are available in nominal sizes such as 1/8", 3/16", 1/4", etc., and also sized .001 under the nominal size or .001 over the nominal size, for example .249 and .251. The under size reamers are used when you want a press-fit or tight fit and the oversize reamers when you want a free or relatively tight fit, as for an axle or rotating shaft. You can buy sets that contain one undersize and one oversize reamer for each nominal size, in increments of 1/16". These are very useful to have on hand when you need them.

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Collet Set and Adapter from Micro-Mark   (10/29/01)

Micro-Mark sells a nice looking collet set for their 7x12 mini-lathe for $139.95.   In addition to the Micro-Mark lathe, it will fit the HF 7x10 and Grizzly 7x12, and the Homier 7x12.

 Micro-Mark Collet Set

Here's the text from their website:

Universal design has MT-3 shank to fit MicroLux lathe and milling machine plus many others. Collet holder has 'snap-in" style collet nut. Includes 8 collets in sizes 1/8, 3/16, 1/4, 5/16, 3/8, 1/2, 9/16 and 5/8 inch, plus drawbar for lathe (drawbar for milling machine comes with that machine).

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Dial Caliper

 

(Update 06/30/08)
I don't recommend these any more. The problem is that small metal chips eventually get into the gears and render the tool useless. Back in 2000-2004, digital calipers were pretty expensive for hobbyist use, but that has changed dramatically (see next article). Now I use only the digital calipers.
(End of update)

I find a dial caliper to be indispensable in my shop - it is one of the tools I use most frequently. In fact , I keep 2 or 3 around so that if one gets misplaced or broken work does not come to a stop. With it you can measure diameters, depths of holes, inside diameters of holes to an accuracy of .001". Good quality ones are available from J&L, Harbor Freight, Grizzly, Enco, etc. for around $15 for a 6" stainless steel version.

Watch out for (1) vernier calipers - these do not have a dial, and are a pain to read since you have to interpolate the reading (2)cheap plastic calipers. In the catalogs they look like the real thing, and often cost as much, but they are junk. Make sure the catalog specifies stainless steel.

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Digital Caliper

 Harbor Freight SKU 47257

Digital calipers are used just like dial calipers for making inside and outside measurements accurate to one one thousandth of an inch but have a direct LCD digital readout. On a dial caliper you first read the major dimension to the nearest tenth of an inch from the slide and mentally add to that the minor dimension from the dial to the nearest thousandth. This becomes second nature after a while, but still introduces opportunities to make a mistake. A digital caliper reads out the full dimension on the display, so is pretty foolproof, as long as it is properly zeroed. You can also switch between metric and inch modes as needed.

They are now available at prices that make them very attractive for home shop use. Harbor Freight has one for $39.99 on sale (08/02) for $19.95 and several purchasers have reported favorably on it. Update: I bought one for myself and am pretty happy with it.  Read the review for more info.

Update (06/30/08)
I have several of these now, and they are one of the most frequently used tools in my shop. They have, for the most part, been accurate and reliable, but I've gotten at least two in which the display continually blinks on and off. That's supposed to indicate a low battery, but these blinked even with a fresh battery. However, HF exchanged them with no hassle for ones that work properly. Good idea to test them before you leave the store, if possible.
End of update

Update (06/26/11)
After a lot of experience with many digital devices (calipers, DROs, etc.) I discovered that using silver batteries eliminates the blinking display issue. There are batteries of identical size, but different electrical properties. The silver batteries are AG13 size, Ag being the chemical symbol for silver.

 Silver (AG) batteries

You can find 10 and 100 packs of these batteries on eBay (search for 'AG13 battery') at very favorable prices. In some cases I have ordered them from vendors in Hong Kong, and they arrived within a week or two via US mail.  As a corollary, avoid batteries sold for hearing aids. I used to use them because they were easy to find locally, but they don't have the power needed for the digitial display tools.
End of update

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Drill Rod

Drill rod is a steel alloy with a shiny silvery color (thus it is known in the U.K. as silver steel) and good machining properties. Unlike other raw materials, which may vary from the nominal diameter by + .010 or more, drill rod is surface ground to within about .001 of the nominal diameter. For many applications, this means that the outside surface requires no additional finishing. While not classified as a stainless steel, drill rod is moderately resistant to rust - more, at least, than ordinary carbon steels. It is great for applications such as shafts and axles. It is available from the usual industrial suppliers typically in 3-foot lengths. Don't confuse this material with Drill Blanks which are short lengths of hardened high-speed steel used for making drills.

A useful property of drill rod is that it can easily be hardened by heating to a red hot state and then quenching in oil or water. Thus treated, the metal is hard enough to use for tools such as punches. Depending on the quenching method, drill rod comes in three types: air hardening, water hardening and oil hardening.

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Drill Sets

Drilling is one of the most commonly performed operations on the lathe, so you will need a good collection of decent-quality drills. When you buy your lathe, don't forget to order a tailstock chuck and arbor to hold the drills.

Poor quality drills are easy to find, but they are truly a waste of money. That's not to say that you need to buy top-quality industrial drills as there are good quality import drills available from the usual suppliers such as MSC, J&L, Harbor Freight, Grizzly and Enco. U.S. made drills from reputable industrial suppliers are nearly always of excellent quality, but I have purchased some U.S. made drills that were real junk. Check the fine print to make sure that the drills you buy are made from High Speed Steel (HSS) and not from softer carbon steel.

It's not always easy to tell a good drill bit from a poor one just by looking and, of course, its even harder if all you have is a picture on a web site or in a catalog.  Generally, though, the lowest priced drill sets are the ones to stay away from.

Drill bits come in several standard size ranges:

• Fractional drills; often sold in sets of 29 from 1/16" (.0625) to 1/2" (.500)  in increments of 1/64"
• Number drills; sold in sets of 60, numbered #1 (.228") to #60 (.040")
• Tiny wire gauge number drills; sold in sets of 20 from #61 (.039) to #80 (.0135")
• Letter drills - less commonly used; sold in sets of 26 from A (.234) through Z (.413)
• Metric drills - sold in 19 pc. sets from 1mm to 10mm in increments of .5mm
• Silver & Demming drills - large size (17/32 to 1") drills with a 1/2" diameter shank

If you are just starting out, a good choice is a set of 29 fractional drills and a set of 60 number drills. Unless you do a lot of metric work, these will meet most of your needs on the minilathe.

 Set of 29 TiN coated fractional inch drills

 Set of 60 black oxide coated number drills

 Set of 119 fractional, number and letter drills

There are several other factors that you need to be aware of when selecting drills. The drills commonly used are called "jobber" drills. These are the type that we are all familiar with that you would find in your local hardware or automotive store. They have a straight shank, the same diameter as the drill and a 119� tip. "Letter Drills", in which the diameters are designated A - Z, are handy when you need a hole size a little larger or smaller than the nearest fractional inch diameter.

(Update 07-26-11)
I've noticed that the drill bits in some of the cheaper import drill sets that I've purchased as "spares" (you can't have too many!) are not perfectly straight as a good-quality drill bit would be.  When you rotate them in the chuck, you can actually see the tip trace out a small circle. Not good!  I don't know how to detect this condition before making the purchase, but when you buy a new set of drills, you might want to check for this condition before you use them and return them to the seller if they are out-of-round.
(End of Update)

Another type that can be handy for the minilathe, especially the 7x10, are Screw Machine Drills. These look much like jobber drills but are shorter - which can be a real advantage within the short confines of the 7x10. I bought a set when I had my 7x10 and on several occasions they enabled me to drill a hole when a jobber drill was too long. You won't find these at a typical hardware store - order them from an industrial supplier such as J&L, MSC or Enco.

Screw machine 3/8" diameter drill bit compared with jobber-length drill bit

Another factor to consider is  the coating of the drill bits. Typically you will find three coating options:

• Uncoated bright steel
• Black Oxide
• TiN (Titanium Nitride)

(Update 07-26-11)
Over the last few years, a number of new exotic coatings have become available. I have not tested these newer coatings, so I can't report on any advantages, but it's pretty safe to assume that a coated drill will outperform an uncoated one by resisting chip welding and thus staying cooler and cutting a cleaner hole.
(End of Update)

Coated drill bits, and especially the newer TiN coated ones, shed chips more easily and are thus less likely to bind or get chips welded to the drill bit surface. Aluminum is especially subject to chip welding, and if it occurs, the welded chips can scour the hole surface and generally mess things up. Additionally, while extremely thin, the TiN coating is very hard and is said to increase drill bit life. I have had good service from TiN coated drills and can definitely recommend them. Usually,   these are better quality drills and selecting them makes it much less likely that you will end up with really poor quality drills.

A final consideration is the material that the drills are made from. Stay away from ordinary carbon steel drill bits - these are often sold in hardware stores and are suitable only for wood and soft materials. The only practical choices for minilathe work are high speed steel (HSS) and Cobalt steel. The cobalt ones are harder and will last longer, but are also more expensive. HSS is a good choice if, like most of us, you are on a budget. One tip to extending the life of any drill set: when drilling a hole, such as a pilot hole, for which the exact drill diameter is not critical, choose an off-size bit. This will save wear and tear on the commonly used sizes such as 1/4" and 3/8".

This covers just the real basics of drill selection. There are dozens, if not hundreds, of specialized drill types used in industry, but for our needs the basic jobber drills in HSS are generally adequate.

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Faceplate

A faceplate is a handy accessory for turning odd-shaped work that cannot easily be held in a chuck. While the Grizzly 7x12 includes this accessory out of the box, one has not been available for the 7x10 until about December 2000. Harbor Freight now offers a cast iron faceplate for the 7x10 as SKU 43582 for 12.99. While it's not too difficult to make your own faceplate from steel or aluminum, at this price it's hardly worth the effort. It will fit any of the Sieg-made 7x mini lathes.

 

The faceplate mounts to the 7x10 spindle in the same way as the chuck, but the 6x1mm studs required are not provided.  You can make your own by parting the heads off of some bolts, if you do not have a source for the studs.

After mounting the faceplate on the spindle, it is standard practice for faceplates to take a light one-time facing cut to ensure that the face of the plate is square with the lathe. Cast iron dust is very harmful to breathe, so I strongly recommend wearing a dust mask during this operation and until you have vacuumed up the resulting dust.

When using a faceplate, always ensure that the work is securely clamped down and balanced by some offsetting piece of metal, if necessary.  Work at low RPMs.

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Feeler Gages

Feeler gages are sets of thin steel strips of accurate thicknesses, typically from .001 up to about .040 or so. There are typically about 20 to 40 separate strips in a set, joined together by a bolt that runs through a hole in the end of each gage. Each gage has the thickness marked on it, in both inches and mm in the example below. All of the leaves fold up into the handle to protect them from bending (or cutting you!) when they're not in use.

 Feeler gage set with a few leaves removed

While their intended purpose is to measure the gap between two surfaces, such as the electrodes of spark plug, when removed from the set, they make nearly ideal shims for adjusting the height of cutting tools - but only until you get a Quick Change Tool Post, of course ;-)  Just remove a few leaves from the set and stack them as needed under the bottom of the cutting tool until the tip of the cutting too is right on the centerline of the lathe. You can find them at automotive stores and probably in the auto parts section at Wal-Mart; also at Harbor Freight.

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Follower Rest

Around December 2000, Harbor Freight started selling a follower rest for the 7x10 as SKU 43580 for $16.99. It will fit any of the Sieg-made 7x mini lathes.

A follower rest is similar to a steady rest, but is attached to and travels with the carriage to provide a moving support for the work behind the cutting tool.  This is very handy when trying to turn limber work which would otherwise bow out away from the tool. If you have ever wondered about the two screw holes on the left edge of the carriage, now you know what they are for - they are the mounting holes for the follower rest.

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Live Center

Centers are often used in the tailstock to support the end of a relatively long and limber workpiece. The minilathe comes with a #2 MT "dead" center. The drawback of a "dead" center is that the center does not rotate, while the workpiece that it supports does, leading to friction and possibly overheating. By contrast, the tip of a "live" center is rotates freely in bearings, and rotates with the workpiece so that the friction is greatly reduced. 

 Live Center mounted in tailstock ram

The Harbor Freight used to (and may still) come with a #2 MT "live" center but the 7x12's that I have owned did not come with one. You can purchase them from a variety of sources, but you will want a very small one with a #2 Morse Taper arbor to work effectively on the minilathe. A good choice is P/N 1189 from LittleMachineShop.com for $12.95 (09/03).

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Medium Density Fiberboard (MDF)  (12/21/05)

MDF is not really an accessory, I suppose, but it is a handy, inexpensive, lightweight and easily workable material to have around the shop. It is a synthetic material something like masonite, but with different properties. It is available in thicknesses up to at least 3/4" and is smooth on both faces. It cuts easily using a saber saw, circular saw, bandsaw, table saw or radial arm saw. One disadvantage is that it tends to absorb moisture, but this propensity can be greatly reduced by spray-painting the surfaces.

It works best for applications such as bench tops since it resists compression well. It is weaker where the edges are exposed and especially when screws must be driven into the edges, since the screws tend to separate the layers that make up the material. Drilling pilot holes for the screws will help prevent this. You should wear a dust mask (preferably a good, industrial-quality one) when cutting MDF since the dust contains formaldehyde which can irritate your throat and lungs.

I have used it for lots of projects around the shop, including an enclosure for the mini-lathe and a base for the mini-mill. You will find it in the lumber section of your local hardware stores such as Lowes and Home Depot, in both 4x8' sheets as well as pre-cut "hobby size" 2x2' and 2x4'  pieces.

 3/4" (bottom) and 1/2" (spray-painted) MDF

 Bandsaw table made of spray-painted 3/4" MDF

 Mini-lathe chip enclosure of 1/2" MDF

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Milling Attachment (10/05/02)

Around September 02, a milling attachment became available as a standard accessory for the mini lathe. It is currently available from Micro-Mark (SKU 82734) andLittleMachineShop.com (SKU 1681) and is most likely made by Sieg, then manufacturer of the 7x mini-lathes. Before this accessory became available, many lathe owners made their own versions based on the one made by Varmint Al. Varmint Al's uses a standard milling vise while the one shown below uses socket head screws to hold the workpiece between the jaws. While by no means a substitute for mini-mill, this accessory is an inexpensive way to add limited milling capability to your mini-lathe while you save up for a mill.

 Milling Adapter from LMS

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Quick Grip Glue

While not exactly an accessory, I find all kinds of uses for this stuff in the shop, but where I find it most valuable is for tacking assemblies in place while prototypingthe design of a component or machine modification. The glue sets rapidly and can be accelerated by pulling the glued parts apart a few times after applying the glue. Hey, it's not my idea, that's what the manufacturer recommends and they're right, it really speeds up the setting time.

This glue is strong enough that I have used it numerous times for permanent installations - especially for attachments to machines where it is difficult and time consuming to drill holes in the cast iron or steel of the machine. It can be easily removed, if necessary, by soaking or flooding the part with some acetone or naptha (use these solvents with caution).

You can find it at crafts stores and in the crafts deparment at Wal-Mart for about $4 per tube. A little goes a long way.

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Steady Rest

Around December 2000, Harbor Freight started selling a steady rest for the 7x10 as SKU 43579 for $24.99. It will fit any of the Sieg-made 7x mini lathes. The Grizzly 7x12 comes with this accessory, as does the ToolsNow 7x12, but it is not included by all vendors.

A steady rest, for the uninitiated, is clamped to a fixed point on the ways, usually near the end, and has adjustable 'fingers' that are adjusted so that they lightly contact the outside of a long and/or limber workpiece to keep it from wobbling or thrashing.

 

On this model, the fingers are brass and are adjusted by means of thumb screws and then locked in place by means of lock nuts. Use a few drops of oil to lubricate the contact surface between the work and the fingers to keep the work from heating up and binding.   The steady rest clamps to the ways with a clamp much like that on the tailstock, and with the same frustrating tendency to rotate to an orientation which does not fit between the ways. My tailstock fix should work here, too.

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T-handle Metric Hex Wrench Set

 
OK, these aren't really essential, but they are so handy and so cheap you will kick yourself if you live without them and then later try them. I use these for nearly all the hex head screws on the lathe. Sets are available on sale for under $10. When you get them you will think they are junk, but mine have held up well for years in spite of heavy use.

Update (01/28/11)
Yup, these things are tough! After 11 years I have never broken one in spite of a lot of use and abuse. I have touched up the tips of a few of them on a grinder; other than that, they have been 100% reliable. I use them so frequently that I bought another set of SAE and metric when they were on sale a few months ago so that I now have them at two locations in the shop.
Update (11-04-13) - Still going strong!!
End of update

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Tailstock Chuck and Arbor

Drilling is a fundamental lathe operation and you will need a chuck and #2 Morse Taper arbor to do it. The arbor has a thread or Jacobs taper on one end - to mate with the chuck - and a #2MT on the other end to mate with the tailstock cylinder.

For quite some time, HF did not offer a chuck and arbor that fit directly in the 7x10 tailstock #2 Morse Taper.  Now they do, and is SKU 42340 for $9.99 (08/03).  At this price, which is about what I paid just for the arbor on my chuck, I decided to buy one just to have as a backup in case my main chuck failed one day and also to keep my web site readers informed.

It's not a great chuck, but is adequate - especially if you are just starting out and are on a tight budget.  My main dislike is that the black metal shell is stamped metal, not a ground casting as you find on a better quality chuck. The other problem, but one that you will most likely encounter with any chuck that you buy for the 7x10, is that the arbor is too long for the tailstock spindle. It fits, but the spindle must be extended out from the tailstock casting by about an inch to seat the arbor in the taper.  Not only is this an inch of lost ram travel, but it is desirable to keep the ram extended as little as possible in order to maximize its rigidity during the drilling operation.

The solution to this problem is merely to cut about 3/4" or so from the end of the arbor.  This can be be done with a hacksaw or a Dremel-type tool with an abrasive cutoff wheel. I cut mine using a cutoff blade in my radial arm saw with the arbor clamped between two pieces of wood in my heavy drill press vise. I took this cut very slowly and carefully since it generates a lot of heat and sparks. 

The following photos compare the arbor on my Grizzly chuck, which also had to be cut down to size, with the arbor of the HF chuck.

To remove the arbor, place the chuck in your bench vise with the jaws open just a little wider than the arbor diameter (not clamping the arbor). Open the jaws up and use a short piece of round stock or a drift pin to drive the arbor out of the back of the chuck. This should only require a fairly light tap of the hammer. It's a good idea to position a rag underneath the arbor to catch it so that it does not get dinged up by falling to the floor.

 

I got my 1/2" chuck and arbor from Grizzly. The chuck is P/N G1649, $16.95 (note as of 2/01, this part number appears to be obsolete. A similar chuck is P/N G8224, $12.95) and the arbor is P/N G1434, $7.95. This chuck has a #6 Jacobs taper.

The #2MT end of the arbor will most likely have a flattened end 'tang' that you will need to remove - otherwise it will be too long for the tailstock cylinder. Check the 7x10 interest group and search for 'tang' for ideas on how to do this.

I used a fiber cutoff blade on my 10" radial arm saw and clamped the arbor between two blocks of wood in my heavy drill press vise. Then I lowered the blade about 1/16" on each pass until I cut through. The cutoff tool throws a lot of sparks so be sure to wear good-quality safety glasses and stay out of the line of fire.

The blade also heats up the workpiece so I used a damp rag to cool it off in between cuts. After cutting, I smoothed the end of the arbor on my disc sander.

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Tool Bits

While I recommend that you learn to grind your own tool bits from Tool Blanks (see below), when you're starting out you may want to buy a set of pre-ground High Speed Steel (HSS) tool bits. Not only will they get you off to an immediate start, they'll serve as good examples of the shapes you want to attain when you grind your own. Here's a very nice set from Walden Specialties. The set includes a 60� threading tool that can be difficult to grind by hand.

 8-pc. Pre-Ground HSS tool bit set

You can also find a selection at LittleMachineShop.com.

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Tool Blanks

Yes, you could buy ready-made carbide tool bits, but learning to grind your own HSS tool bits is a valuable skill and part of the fun of learning to use the lathe. You will soon learn to grind special tools for parting, boring and other operations.

Tool blanks are available from many sources; I usually get mine from Enco (on sale for as little as 80 cents each) but have also bought them from Grizzly, J&L and other suppliers. All of the 7x10 and 7x12 lathes use 5/16" x 2 1/2" tool bits except for the older model Homier/Speedway  which use 3/8" x 2 1/2" tools. (This is true for some pre-1999  7x10s as well).  Before ordering, it's a good idea to check the height from the lower surface of the tool holder (where the tool sits) to the tip of a center in the headstock or tailstock. Be sure that the tool blanks you order are a little smaller (on each side) than this distance.

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Transfer Punch Set

Transfer punches come in sets sized like twist drills. Import sets are available for under $10 and are fine for hobbyist use since they are used infrequently. They are hardened steel with a pointed tip and are used to 'transfer' the location of a hole in one workpiece to a mating surface in another workpiece. A punch is selected that just fits within the original hole and is struck lightly with a hammer to make a punch mark that will be at the center point of the hole. They are also handy as for determining the inside diameters of small holes.

 

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Quick Change Toolpost

A quick change tool post (QCTP) is an accessory that I strongly recommend: get one as soon as your budget allows.  Why? It will save you hours of time and lower your blood pressure by several points since you'll no longer have to stack shims under the tool bit to get it to match the height of the lathe centerline. With a QCTP, each cutting tool has its own dedicated holder. Each holder has a locking height adjustment. A few quick trials and adjustments and you lock the tool height to the perfect setting. You won't need to adjust it until you sharpen the tool, which may lower the tip by a few thousandths.

But that's not all: switching tools between operations is a snap; 15 seconds or less, and the new tool that's in place will be at the right height. The only downside to a QCTP is the relatively high price (about $100 for a set as of Jan. 2009), and you'll soon find that you want lots of toolholders. The more the better! If you have a mill, you can make your own toolholders to trade time for money. If you're really hardcore, consider making your own QCTP and all the toolholders you want from theplans in my Premium Content pages.

The one in the photo was made by TS Engineering, but they are no longer selling them  as of   2009.  LittleMachineShop.com has several other varieties to choose from, including models to fit lathes such as the Taig, Sherline, Atlas, C4 and others.

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Wet/Dry Sandpaper

Wet / Dry sandpaper is very handy for putting a very fine shiny finish on metal workpieces in the lathe. In that application it is generally used dry, but when used wet on a flat backing surface it does a great job of smoothing flat metal workpieces from milling operations.  You will need a variety of grits such as 220, 320, 400 and 600 and can sometimes find assortment packs that contain such a variety. You can find it in the paint section of most hardware and automotive stores.

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White Lithium Grease

White lithium grease is useful for lubricating just about any of the moving parts of the lathe. (Use light oil on the ways, though, not grease).   I buy it at Sears' tool department in small tubes.  Two of these tubes should last you a year or more.

Update (06/30/08)
I tend to use regular motor oil (e.g. 10W-30) for most of the lubrication on the lathe and mill nowadays. The lithium grease is still handy for certain applications, though.
End of update

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Mini Lathe Adjustments

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Table of Contents

• Disclaimer
• Adjusting the Gibs
• Adjusting Cross-Slide Backlash
• Adjusting the Saddle
• Adjusting the Tailstock
• Adjusting the Motor and Drive Belt
• Removing and Lubricating the Headstock
• Tear down & Rebuild  the Headstock to replace gears or bearings (photos from Sieg, no text provided; maybe someday I'll add some text [FJH].

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If you have not already done so, please read the Disclaimer (last updated 10/18/09)

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Tuning Your Mini-lathe

There are several adjustments you can make to significantly improve the accuracy of your minilathe. These adjustments, properly done, can improve the quality of work you can produce. To get accurate, nicely finished work and minimum chatter, it is important to remove as much play as possible in the saddle, cross-slide and compound. Try grasping the compound and twisting it from side to side. If your lathe is properly adjusted you should be able to move it very little.

Adjusting the Gibs

One of the simplest and most effective adjustments is adjusting the gib screws. Gibs are metal strips that sit on one side of a dovetail slide, such as the cross-slide and compound, and which are adjustable to take up any slack or slop so that the dovetail slide is very smooth and snug.

Looking at the side of the compound rest you will see 3 small set screws surrounded by locking nuts.

If you crank the compound rest all the way back until the compound lead screw disengages, you can then slide the top part of the compound free from the bottom part, exposing the lead screw, dovetails and gib strip. Here's a view of the underside of the top part of the compound rest.

Viewed end-on the gibs are parallelogram shaped. On the back side of the gib you will find 3 indentations which act as engagement points for the adjusting screws. Some owners have mistakenly thought that these indentations were manufacturing defects - they are not - they are there to hold the gib in place on the tips of the adjusting screws.

 

Look at the working face of the gib. As it comes from the factory these are usually pretty rough. Check my lapping page for information on how to polish this face to a shiny finish to get even more accuracy and smoothness from the dovetails. In the picture below, the gib has been polished.

While you have the compound removed, apply a light coating of white lithium grease to the gib face, the dovetail faces and the lead screw. White lithium grease is available from hardware stores in small plastic tubes which will last quite a while.

(Update 1/26/09)
I used WLG for a few years after I first got my lathe. Since then, I have switched to regular old automotive oil for lubricating most parts of the lathe. The WLG still comes in handy for may other lubricating jobs, though.

  

With the compound back in place and positioned about midway in its range of travel, here's the adjusting procedure:

1. Use a 7mm wrench to slightly loosen each locking nut
2. Start with the middle screw, grip the lock nut with a 7mm wrench and tighten the set screw using a 2mm hex wrench until the set screw is just snug.
3. Back off the set screw about 1/4 turn
4. Holding the set screw to keep it from moving, tighten the locking nut. The lock nut should not be super-tight, just tight enough to firmly lock the set screw in place.
5. Repeat for the other two adjusting screws.

Now test the compound slide to make sure it moves smoothly. If you get the gib too tight it will lock the slide in place so don't force the crank or you might strip the leadscrew. Just repeat the above procedure but don't tighten the gib screws quite so much. Try tightening the set screws slowly while you are cranking the compound back and forth and you can feel the gib start to snug up the dovetail. This should give you a good sense of how tight the screws need to be.

You may have to repeat this procedure several times until you get a feel for it. As you use the lathe, the dovetails and gib will wear down a little over time so you will need to repeat this procedure periodically.

After you have the slide moving smoothly, try gripping the compound rest at either end and try to wiggle it side-to-side. There should be almost no play at all.

The procedure for adjusting the cross-slide is essentially the same. The gib screws for the cross-slide are on the tailstock side of the slide:

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Adjusting Cross-slide Backlash

Grasp the cross-slide at either end and try to slide it back and forth. You will probably feel a movement of about .100 inches or more. By performing the adjustment described here you should be able to reduce this movement to about .020 or less.

The cross-slide lead screw engages with a rectangular brass nut attached to the underside of the cross-slide by two hex screws. A third hex screw presses against the top of the brass nut to adjust its height. By adjusting this middle screw and the two mounting screws, you can adjust the brass nut to minimize backlash in the cross-slide. It's a crude mechanism, but it works.

Here's a picture of the underside of the cross slide showing the brass nut.

Here's the lead screw:

In the next photo you can see the three adjusting screws near the back end of the cross slide. The compound has been removed.

This shot shows a a close-up of the nut removed and inverted so that you can see the arrangement of the adjusting screws.

Here's the adjusting procedure:

1. Loosen the two outer screws using a 3mm hex wrench
2. Loosen the middle screw using a 2.5mm hex wrench
3. Tighten the middle screw until it is just snug
4. Tighten the two outer screws until just snug

Grasp the slide and slide it back and forth again. By alternately tightening the center screw and outer screws you can remove as much of the backlash as possible. Like most adjustments on the mini-lathe, you need to play around with it a while to get a feel for it. Be careful not to overtighten the screws or you could strip the threads.

You don't need to remove the cross-slide to adjust the backlash, but you may want to do so to lubricate the dovetails and leadscrew and to polish the gib strip. The top of the cross-slide must be removed by sliding it off the back of the bottom section. One way to do this is to remove the splash guard. Alternatively, you can slide the saddle off the end of the ways. More on this later...

Here's an explanation of the procedure by Bruce Simpson:

The two screws you talk about which "tighten" the cross-feed nut 
aren't just there to secure it -- they're an adjustment designed to take 
up the slack.

If you just torque them down then you will find the handle pretty hard 
to turn.

The nut itself pivots on the center (flat-head) screw and the cap-head 
screws either side are their to tilt it.

By tilting the nut you can progressively reduce the backlash.  The 
goal is to obtain a degree of tilt that minimizes backlash without 
unduly increasing friction.

You should adjust these screws with the cross-slide in the fully 
wound-in (i.e.: towards the rear of the lathe) position because it's also 
possible to have the nut too high or too low which means it will bind on 
the feed screw when it gets to that end.

Play around with the three screws until you get it right.

The technique I use is to slacken the two cap-head screws and use 
the middle screw to set the height of the nut (so it doesn't bind when 
the cross-slide is wound right to the back) 

Then slowly tighten one (doesn't matter which one) of the cap-heads 
until you notice the slop starting to disappear.  Once you've got the 
slack out you tighten the other one so that the nut is then firmly held.

You'll likely find that when you tighten the other cap-head screw that 
things free up a little and some of the backlash comes back -- this 
means you may have to over-tighten the first screw a little in 
anticipation of this change.

Another thing to watch is that you might need a shim behind the 
collar on the cross-feed screw where it presses against the cross-
slide.  It's not uncommon to have quite a bit of slop here and the 
judicious use of some steel or brass shim cut into a washer shape 
can work wonders here.

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Adjusting the Saddle

When you turn the carriage handwheel, the saddle should move easily along the ways without binding, but should be tight enough so that there is very little slop or play. With the carriage about midway along the ways, grasp the carriage firmly and try to rock it back and forth. There should be very little movement if everything is properly adjusted. Too much play will cause chatter during cutting operations and will make it difficult or impossible to get a smooth, clean cut.

Look carefully at the gap between the lower edge of the saddle where it rests on the ways and the ways.  If the gap opens and closes as you rock the saddle, there is too much play and you need to tighten the saddle adjusting strips. The adjusting strips are two rectangles of fairly soft iron located on the underside of the saddle.  There are three adjusting screws and two locking screws on each strip.

They are tricky to adjust properly, since you can't easily get access to the adjusting screws while the saddle is mounted on the ways. Therefore, you usually have to slide the saddle off the end of the ways, make a slight adjustment, remount the saddle on the ways and test and repeat this process until you get it right. To make matters worse, the adjusting screws on the front side of the saddle are obstructed by the half-nut and the pinion shaft. (Note: you can avoid this painful procedure by doing my "Top Adjusting Saddle" Premium Content project)

When attempting to slide the carriage off the end of the ways to gain access to the adjusting screws, the carriage will sometimes stick at the end of the ways. This is caused by the raised metal where the serial number is stamped onto the end of the ways. Use a file or sharpening stone and make a few light passes over the serial number to remove any raised metal.

The set screws with the lock nuts work to push the plates away from the bottom of the ways, while the three cap screws work to clamp the strips tighter to the ways.   The goal is to work these two sets of screws in opposition to each other until the guide strips are as snug as possible on the ways without causing excessive resistance.   Apply a little light oil along the surface of the ways and work the saddle back and forth.  With a little work, you should be able to get the movement to be pretty smooth with very little slop.

Caution: the metal strips are brittle and will crack  at the position of the set screws if you apply excessive force.  Sooner or later this seems to happen to many lathe owners. I replaced the originals on my 7x10 with new ones I made from brass.

Here's a procedure suggested by Bruce Griffing:

I began by removing the saddle.  I also removed the apron, though that is not necessary.    On each side, there are 3 socket head cap screws and two adjusting screws.    In this procedure, you remove the two end SHCS's and don't use them until the end.   You begin by alternately loosening the center cap screw, adjusting the two adjusters and tightening the center screw until you achieve a 30 mil gap at both ends of the cast iron strip.   In this case the gap is measured between the iron strips and the saddle.  I used a feeler gage to measure the gap.  This should be done for both sides of the saddle. 

The next step is to loosen the center SHCS and put the saddle back on the lathe.    Tighten the center SHCS and measure the gap between the ends of the strap and the underside of the ways.    This should be done at both ends and on both sides.   If the gap is zero, go back to the beginning and increase the initial gap to 40 mils.   But it should be greater than zero, so record all 4 values.   Remove the saddle again and do some math.   If the gap with the ways was 12 mils then you want to reduce the  saddle gap from the initial 30 mils to 19.  This will reduce the gap with the ways to 1 mil - the target.  

This should be done for both ends of the strip - so it is a balancing act between the two adjusting screws.   Once the correct gap is set at both ends of both sides, install all of the SHCS's but leave them loose.  Reinstall the saddle and tighten the center SHCS on both sides.    If the 1 mil gap is correctly set, the carriage will move freely at this point.    Then the end SHCS's are adjusted to achieve the desired trade between rigidity and friction.   At this point, you are bending the strips to close the one mil gap at each end. 

This method works very well and is much easier than it sounds.   It minimizes stress on the strips and achieves good balanced retaining force.  It may be old news, but I haven't seen it yet.   One minor point - to do this you need some narrow feeler gages.  I actually used shim stock to measure the strip to way gap. 

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Adjusting the Tailstock (06-04-12)

The minilathe tailstock is made from two separate castings. The upper casting can be moved in or out, relative to the lathe centerline, to taper a workpiece, heldbetween centers, along its length. For all other operations, the tailstock must be exactly aligned with the lathe centerline. If it's not, supporting a workpiece with a center in the tailstock, or drilling with a chuck in the tailstock will produce skewed results and possibly break drill bits. The tailstock can become misaligned due to rough handling during transport, by dropping the tailstock or by a previous use where it was offset for cutting a taper.

 The upper casting can move along the raised area on the lower casting

The upper casting is locked in position by a setscrew at the back of the tailstock and a socket head cap screw underneath the tailstock. If the setscrew at the back of the tailstock has never been removed before, it probably will be locked in place by paint. Working it with a screwdriver that properly fits the screw slot should break the paint free, but be careful not to strip the slot or your problems will be magnified. If the screw is really stubborn, a few drops of acetone, paint thinner or nail polish remover may help to soften up the paint locking the screw in place.

 Set screw on back side of tailstock (sealed with paint)

 Cap screw under the tailstock base

The screw underneath the tailstock can most easily be accessed by sliding the tailstock off the end of the ways. On some models of the minilathe, a stop screw, intended to keep the tailstock from accidentally sliding off the ways, may first need to be removed from the end of the bed.

 Some mini-lathes have a tailstock stop screw

To offset the tailstock, first loosen the set screw and the cap screw just enough so that the upper casting can be moved by tapping it with a light force. I use the plastic handle of a large T-handle hex wrench like a soft hammer for that purpose, but depending on how tight the fit is on your minilathe, more force may be needed. If you can't get the upper casting to move, it may be sealed by paint. Here again, a small amount of acetone, nail polish remover or paint thinner may help loosen it up. Once the tailstock is offset by the desired amount, tighten the two screws to keep the offset from shifting, but watch out - tightening the screws sometimes shifts the offset.

After completing the tapered cut, loosen the two screws as before and tap the upper casting as needed to bring it back in line with the lathe centerline. One way to do this is to place a #3 dead center in the headstock and a #2 dead center in the tailstock and adjust the tailstock offset until the tips of the two centers are aligned as closely as you can get them.

An old machinist's trick is to position a thin piece of shim stock, or a thin 6" machinist's rule, no more than about .015" thick, held lightly between the points of the two centers. A leaf from a set of automotive feeler gages, 0.005 - 0.015" thick, is also good for this test. If the centers are not lined up, the thin metal blade will tilt towards the headstock or tailstock.

 Using a feeler gage to test tailstock alignment

In the photo above, the tailstock center is closer to the front of the lathe than the headstock center; the upper tailstock casting needs to be shifted a very small amount towards the back of the lathe. When the two centers are exactly in line, the blade will be perpendicular to the lathe centerline.

Once that position is found, first tighten the set screw on the back of the tailstock and check to be sure that the alignment did not shift. If the blade is still perpendicular, carefully slide the tailstock off the back of the ways and then tighten the socket head cap screw underneath. After tightening, recheck the alignment, as tightening the screw may shift the alignment. It may take several tries to get it just right.

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Adjusting the Motor and Drive Belt

The motor is mounted on the back side of the lathe below the headstock. A toothed drive belt runs from a small toothed  pulley on the motor shaft up to a larger pulley on the back end of the spindle.  This is normally not visible since it is behind the gear assembly, but the assembly can be removed by means of two hex head cap screws located at the upper left and lower right corners of the casting. It is not necessary to remove this cover to fix the belt alignment, but doing so will help you to see when the belt is properly aligned.

In the photo above, the belt is slightly misaligned. You can see that it is not properly centered over the upper pulley and is running pretty close to the side of the headstock.  The motor is canted slightly so that the left side is lower than the right side - this is probably why the belt is off center and leveling the motor will probably correct the problem.

The position of the motor and the belt alignment and tension can be adjusted by means of the motor mounting bolts and positioning bolts. These are located on the front side of the headstock, behind the electronics box.

To get access to these screws, remove the black plastic shield above the leadscrew and the leadscrew. To remove the leadscrew,

• Remove the pillow block from the right end of the leadscrew
• Remove the gear from the left end of the leadscrew
• Remove the bushing and key from the left end of the leadscrew
• Slide the leadscrew to the right out from the pillow block on the left end.

Now you can get a better view of the adjusting screws.

  

The two bolts with the washers under the nuts hold the motor in place.  Once loosened, it is easier to adjust these nuts with a 10mm nutdriver (or socket wrench) than with the open-end wrench that comes with the lathe. The other two set screws push against the cylindrical motor housing and can be moved in and out to adjust the position of the motor.  Moving the upper screw inward pushes the upper part of the motor back and tightens the belt. Moving the lower screw inward has the opposite effect. As the motor is moved, the alignment and tension of the drive belt are changed. 

When properly aligned, the belt should not touch any part of the lathe other than the two drive pulleys.  To correct a problem with the belt rubbing against some other part of the lathe,

• Mark the original position of the motor mount bolts using a Sharpie pen
• Loosen the two motor mount bolts
• Loosen the alignment bolts
• Move the motor by hand until the belt appears to be properly aligned
• Tighten the mounting bolts finger tight
• Tighten the alignment bolts until they press against the motor housing
• Tighten the mounting bolts firmly
• Turn the lathe on at slow speed, check the belt and repeat until fixed.

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Removing and Lubricating the Headstock

The lathe spindle runs through the headstock supported at either end by precision thrust bearings. A keyed shaft runs through the headstock below the spindle and supports a large and a small plastic gear on either end of a common midsection. This gear assembly is keyed to be driven by the shaft, but can slide along the shaft.  The HI/LO lever moves a forked piece of metal which sits between the two gears, thus moving the gears from side to side along the shaft and engaging them with corresponding gears on the spindle.

    

Users who have ventured to look inside the headstock have generally found that there is little or no lubrication on the gears, shafts and levers. On my lathe, the HI/LO lever seized up after a few months of use, leading me to investigate the inner workings of the headstock. Once you have gained some confidence disassembling and reassembling some of the basic parts of the lathe, it is a good idea to remove the headstock and thoroughly lubricate the moving parts with white lithium grease or similar lubricant.

Removing the headstock takes quite a few steps, and you should carefully set aside all the nuts and bolts as you remove them and keep track of where they came from. The headstock is bolted to the lathe bed by three hex head cap screws which are very tight and are somewhat difficult to get at. These are best loosened by means of an 6mm hex wrench driven by a 3/8" socket wrench and flex-coupling. Some owners have been able to remove them by using a hex wrench with a piece of strong tubing used as extension for extra leverage.

  

Here are the steps:

• Remove the leadscrew

• Remove the pillow block from the right end of the leadscrew
• Remove the gear from the left end of the leadscrew
• Remove the bushing and key from the left end of the leadscrew
• Make sure half-nut is disengaged (or remove carriage)
• Slide the leadscrew to the right out from the pillow block on the left end

• Remove the speed control box
• Unscrew ground wires from headstock casting
• Remove the black plastic guard above the motor mount screws
• Loosen and remove the two hex head cap screws securing the front of the headstock
• Remove the sheet metal cover from the motor in back of the lathe
• Loosen the motor mount screws and move motor aside
• Remove the single hex head cap screw securing the back of the headstock (in motor recess)
• Lift headstock casting off of ways.

   

Once you get the headstock off, use your finger or some kind of applicator to liberally spread grease on the moving surfaces. I recommend that you remove the HI/LO lever and lubricate the shaft where it passes through the side of the  headstock.

I have never removed the main bearings or the spindle on my lathe. (Well, that was true when I wrote this years ago. Since then I've done it quite a few times.) I have avoided this under the assumption that their alignment is critical to the accuracy of the lathe.  Here are some pictures on how to do this, sent to me by the Sieg factory.

Reassembly is basically just a reversal of the above steps but you will need to realign the motor mounts so that the drive belt runs freely. The base of the headstock has a V-groove ground into it which mates with the ways to ensure proper alignment when the headstock is reinstalled, but make sure no chips or grit are on the base of the headstock when you reinstall it.

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