Frequently Asked Questions About Sherline Tools

by Joe Martin, President and Owner of Sherline Products, Inc.

When someone asks what is the accuracy of a machine, it is actually a rather loaded question. The more you know about the subject, the more difficult it becomes to answer. I can easily turn a diameter close to the chuck on the lathe within .0002" (2 tenths of a thousandth of an inch). Does this mean the machine is built to that tolerance? No, but it does mean the lead screw is accurate*, the cutting tool is proper and the diameter I am cutting is large enough not to deflect. In many cases, the accuracy of your method of measuring has as much to do with the accuracy of your parts as the machine you are working on.
* NOTE: Sherline's leadscrews are precision rolled and are accurate to within 99.97%

The tools we make are as accurate as you can build them without expensive grinding and heat treating. We have over a million dollars invested in state-of-the-art CNC machine tools and tooling to mass produce accurate parts. To increase the accuracy less than 1% would increase the cost by a factor of 10. This simply wouldn't be cost effective for the average consumer of our products. The jump from our $410 lathe to a $4000 lathe of similar size yields only a minor increase in accuracy, and could result in a loss in versatility, as few other machines offer the combination of features and complete system of accessories available from Sherline.

When asking about the accuracy of the machines, what is really being asked is, "what kind of accuracy can I expect to achieve in the parts I make on these machines?" When you look in our new catalog at some of the examples of the parts made on Sherline machines, you can see that, in the hands of a good craftsman who knows his or her machine, the parts that can be produced are as accurate as you will ever need. You will find that most problems associated with making very tight tolerance parts are not caused by the machines but rather are the result of the level of craftsmanship of the operator. As your technique improves, you'll find your machine keeps making better and better parts.

Even if the machine were "perfect", other things can affect accuracy. For example, the "spring" or deflection of the part you are making and the deflection of the cutter also affect accuracy. Taking all this into account, it is still not uncommon for a good machinist to be able to make parts accurate to within a thousandth of an inch or less on our tools. Keep in mind our lathe is a small engine lathe, not a jeweler's lathe. If you are a hobbyist, the Sherline lathe for under $500 will be plenty accurate and many times more useful than the most expensive jeweler's lathe made, as they are designed for different purposes.

Keep in mind also that while you need a big machine to make big parts, it is much easier to make accurate small parts on a small machine. In addition to the advantages of being able to sit down and get close to your work, the smaller machine will give you a much better "feel" for delicate work than a large machine. For example, it is very easy to break extremely small drills if you don't have some feel for how fast to feed them. A large machine simply cannot give you the "touch" you need for doing delicate work.

The biggest enemy of accuracy here is the versatility of the machine. Because the head rotates to allow taper turning, returning it to a perfectly straight position is dependent on the alignment of the headstock key and keyway. We recently replaced the standard square key stock material with a precision ground key, which has increased the level of accuracy. (New precision ground keys are only $2.00 if you wish to upgrade an older machine.) New assembly procedures in the factory to align the headstock and tailstock have also brought the accuracy of that alignment to even higher levels. (Within less than .003" or .08mm) We also manufacture adjustable tailstock tool holders and an adjustable live center, which can help you attain near perfect alignment should your job require it.

Backlash is the play in the engagement of the leadscrew threads which allows a few thousandths of an inch to be turned on the handwheel before the leadscrew starts to turn when changing directions. This is a fact of life on any machine tool and is accounted for by always making your cuts in the same direction and keeping track of which way you turned the handwheel last. Backlash is usually set to about .003 to .005" (.08mm to .12mm). The X-Y leadscrew on the mill has a backlash adjustment, but it is still recommended that it be set to .003".

There are almost no limits to the kind of materials you can machine. Anything from wood or plastic to exotic materials like stainless steel can be cut as long as the part can be safely and firmly held and the proper cutting tool and cutting speed are used.

The Lathe is capable of turning a 3.5" (90mm) part over the bed. The fact that the lathe will turn to 3.5" does not mean you can turn a 3.5" diameter between centers, because the crosslide would be in the way. The lathe will turn a part 1.875" (48mm) over the crosslide. A 1.25" riser block kit increases that to over 5.5" (140mm) over the bed or 4.3" (109mm) over the crosslide. A .405" (10mm) diameter hole through the headstock allows long material of up to that size to be fed through and worked on. The standard lathe has 8" between centers and the long bed lathe has 17" between centers.

That gives you the physical limitations of the machine, but what does the hardness of the material you wish to turn do to those numbers in the real world? A good rule to remember when it comes to purchasing any lathe is to take the average diameter you plan to work with and multiply that times three for free machining materials and times four for tough materials like stainless steel. If the materials you plan to work with are free machining (aluminum, brass and free machining steel), you will be pleased with a Sherline lathe if the average part you make is approximately 1" (25mm) in diameter. Wood and plastic are so easy to machine that only size limitations need be considered. I don't mean to imply that you can't machine a 3" flywheel, but if you are planning to consistently make parts of that size, you will probably be happier with a larger machine and more horsepower. Removing large amounts of metal on a small machine takes time. If you have lots of time, size of the part is less critical. Users of any machine are happier with its performance when they are not consistently pushing the limits of its capabilities. If you usually make small parts well within the capabilities of the Sherline lathe and every once in a while need to turn a part sized near the machine's limits, you will be very satisfied with the its performance.

The vertical milling machine is capable of holding larger parts than the lathe because the part is held and only the tool turns. It also has a much longer table throw ("X" axis). A deluxe version is available which offers an additional 2" of "Y"axis travel compared to the standard mill. It also includes a mill headstock spacer block which adds 1-1/4" to the throat distance (clearance between the tool and the vertical column). With the addition of the horizontal milling conversion, surfaces up to 6" x 9" can be machined without moving the part. This is a very large machinable area for a tool of this compact size.

The 90 Volt DC motor offers far more torque than the 1/2 HP AC/DC motors we used to use. (It is also much smoother and quieter.) The electronic speed control adjusts automatically for any voltage world wide from 100 to 240 volts, 50 or 60 Hz. An electronic circuit in the new speed control unit also compensates for load, keeping the RPM more constant during cuts. Everyone is impressed by how powerful the motor actually is when they use it. The electronically controlled speed range of 70 to 2800 RPM requires no changes of gears or belts to achieve. Just turn the speed control knob for any speed in that range. For example, half speed is about 1400 RPM. (It is not necessary to know the RPM exactly, because your initial approximate speed setting will be adjusted by looking at the chips and listening to the cut as you become more experienced.) For even higher torque at low speeds when turning large parts, a second drive belt position is available on the motor drive and headstock pulleys. (By the way, to buy just a DC motor and speed control of this quality elsewhere could cost you more than the entire model 4000 lathe!)

Introduced in September, 2001 was a new pulley set that allows the motor to turn the spindle shaft at 10,000 RPM. This kit (P/N 4335) can be added to any existing Sherline (DC motor) machine or a complete headstock, motor and speed control with the 10,000 RPM pulley set already installed can be purchased as P/N 33070. A second pulley position on the same set allows the speed range to be set for a maximum of 2200 RPM for greater torque. Higher speeds are helpful when turning very small shafts or using very small cutting tools.

This depends mostly on the diameter and type of material you are attempting to cut. It is also dependent on the sharpness of your cutter and the firmness of your setup. The high torque DC motor we use is very powerful for its size. In fact, it is more common for people to underestimate its abilities and feed the cutting tools too slowly causing the tool to "chatter". For aluminum, you could expect to be able to take cuts of up to .060" on 3/4" diameter stock, while stainless steel would require taking no more than .015" with each pass. (In another example, on free machining steel, you could take that same .015" cut on a 3" diameter piece.) Heavy cuts at high RPM will also cause the tool to "chatter". Metal must be cut with enough feed to keep the cut continuous (keep the tool biting into the metal). Rule #1 in any machining operation is: "If the tool chatters, reduce speed (RPM), reduce depth of cut and increase the rate of feed."

With the addition of the optional Thread Cutting Attachment (P/N 3100), the Sherline lathe is capable of cutting almost any size thread. It will cut 31 different unified thread pitches from 80 to 10 threads per inch and 28 different metric pitches from .25 to 2.0mm. You can also cut any of those as right or left-hand threads. Inch threads can be cut on a metric machine and metric threads can be cut on an inch machine. You never need be limited to threads available in standard tap and die sets again!

Most milling machines are three-axis machines; that is, there are handwheels to move the part in the "X" axis (left/right), the "Y" axis (in/out) and the "Z" axis (up/down). In addition to this, the standard Sherline mill has a headstock that can be rotated for angled milling. This is a direction of movement for the cutter, but it is not an "axis" of movement for the part. The Model 2000 mill has a ram/column arrangement that also allows the headstock to be moved in and out, pivoted side to side, swung back and forth and rotated side to side. These additional four directions of movement make a total of eight possible directions either the part or headstock can be moved. As far as part movement, however, even the Model 2000 mill is still considered a 3-axis machine. A "4th axis" of movement is usually a rotary motion, and this can be added to any Sherline machine with the addition of a rotary table. By definition, then, the Model 5000 and 5400 mills are 3-axis machines with one additional direction of possible headstock movement. The Model 2000 mill is a 3-axis machine with an additional five directions of possible headstock movement. Obviously, the potential setups on a machine with more directions of movement are more diverse.

Both your skill level and the nature of the jobs you intend to take on will determine the level of sophistication of the mill you need. Most beginners simply do not need an 8-direction mill. Each time one of the directions of movement is taken out of square, it must be "indicated" back to square when the job is done. This is a fact of life with a full-size machine like a Bridgeport® mill, and every machinist must become familiar with squaring up his mill. However, on the standard Sherline mills, since there are less ways to get it out of square, less time must be spent putting it back in square. This is one of those engineering tradeoffs we always speak about where any change usually brings both an advantage and a disadvantage. Often, setups that require a part be machined from several angles at once can be achieved with the use of a tilting angle table that holds the part at an angle rather than angling the headstock. The capability of angled drilling can also be added to a standard mill either by tilting the part on a tilting angle table or by adding a rotary column attachment. These methods work well on small parts; however, some castings, for example, may be too large to be attached to a tilting angle table and the more versatile mill is the best solution.

There are many things to learn when first using a mill. I do not like to see a new machinist become discouraged by trying to use a machine that is more complicated than he needs. However, a machinist with some experience will immediately appreciate the outstanding versatility of a sophisticated, multi-adjustable machine. If you are not sure you need the many levels of movement available on an 8-direction machine, I would suggest you start with a 5000 or 5400 mill. At any time you decide you need more sophistication, your machine can be upgraded to the full capability of the 8-direction machine by installing a column conversion. The difference in price between a Model 2000 mill and a Model 5400 mill plus an 8-direction conversion kit is only $25.00 ($875 vs $900), so there is little disadvantage to putting off that decision until you are sure you need it. If money is no object and you simply want "the best", and are willing to take the time to learn to use the extra capabilities, then by all means dive in head first and start out with a Model 2000.

The column and ram components used in the Model 2000 mill allow several more directions of movement than are available on the standard models. When I tested the prototype, I ran the table out to the end of its travel and extended the ram to its maximum overhang to fly cut a part held out on the end of the table. This is a very extreme setup that you would probably never use, but the machine had to work even in this configuration or it wasn't worth making. Just as on a full size mill, the size of cut you make must be scaled back somewhat when moving away from the center of the machine, but the cut was quite acceptable. The cross section of the components on all the machines are designed to be appropriate for the loads that can be applied by the motor supplied with the machine. Keep in mind that we are talking about 1/3 horsepower here, not 3 horsepower, so the column and ram are sufficiently rigid.

All Sherline lathes and mills are now offered as "CNC-ready" machines as an option, or any existing Sherline machine can be converted to CNC-ready status with a conversion kit. This means the handwheels are removed and a stepper motor mount is installed. CNC stands for "Computer Numeric Control", which means the movement of the leadscrews is controlled by a computer that drives a stepper motor to rotate them. "CNC-ready" means the machine is ready for you to bolt on stepper motors. You must also supply your own computer, stepper motors, motor drivers and software. The Sherline conversions do include the handwheels that would normally come with any given machine. When using a dual-shaft stepper motor, this means you can still turn the handwheels for manual control if you so desire. (NOTE: the stepper motor should be disconnected before you do so to keep it from acting as a generator and possibly damaging your computer.) High quality stepper motors are available from Sherline as an additional option.

A number of aftermarket suppliers can provide the parts to turn your "CNC-ready" machine into a complete CNC system. These suppliers are listed on our "dealers" page under "cnc dealers". Just about any configuration you need is available, from retrofit kits to complete turn-key systems. Most require a separate computer, but the computing power required is not high and a 486 or better computer will usually work. Most of us have an old computer sitting around somewhere that will work, or used computers of sufficient capacity are available at very low cost. Sherline does not recommend one system over the others, because each has its own strengths. We recommend you look up the web site of each supplier and see which one best suits your needs. A link to each supplier's site is provided from the list.

Sherline's standard 1-year warranty still applies to CNC-ready machines, whether purchased from Sherline or from one of our suppliers. However, we do not warranty the software or other non-Sherline components that may be supplied by these aftermarket companies, so warranty service on those items must be obtained from the supplier. Technical support on the software must also be obtained from the supplier, not from Sherline.

By the way, Sherline does now offer a single-axis CNC controller that can be used to drive a stepper motor attached to any CNC-ready axis of a Sherline machine. This hand-held controller is completely self-contained and can be programmed with simple commands via the built-in keypad. One controller is required for each axis, but they can be "daisy chained" together to signal each other, allowing you to automate some fairly sophisticated tasks with very little effort. There is also a controller for the rotary table that allows you to program indexing tasks. By daisy chaining a rotary controller and a linear controller, for example, complete gears can be cut with only five input commands and the push of one button to start the sequence. While this is not a full CNC setup, it may be sufficient for your job.

Yes. Over the past two decades, we have added accessories each year to make this the most complete line available from any single machine tool manufacturer in the world, regardless of size. Any machine shop job you might attempt can be achieved in miniature on Sherline tools. Accessories include attachments for thread cutting, knurling, indexing, boring and fly cutting. We have a 4" rotary table, mill vise, power feed, wood tool rests, and a large selection of 3-and 4-jaw chucks and tool posts. High speed steel and carbide cutting tools can be ordered as well as center drills, end mills and collet sets. We also make special tools for watch and clock makers.

No. In fact, a good craftsman will often do better than a professional machinist on small tools. Machinists work all day with big machines that cost thousands of dollars, and will often tend to push a smaller machine too hard. It's sort of like a race car driver going to the airport in a 4-cylinder rental car...he'll have his foot to the floor the whole time and wear the car out in a hurry!

What a good craftsman will find is a whole new world in which to express their creativity. Things that were impossible to do before become simple operations. Sherline tools were designed to be operated by people with a good, "common sense" knowledge of mechanics. We provide the most complete instructions in the industry. With our tools, accessories and instructions plus a willingness to take the time to make good parts, you have everything you need to enjoy the world of miniature machining.

Unlike the instructions that come with most machine tools, your SHERLINE lathe and mill come with an illustrated color instruction book that goes far beyond just the setup and operation of the machine. In it you will find all the basic machining knowledge you need to start making parts right away. If you want to read it before you buy, it's all available on our Web site. See the section called "Setting Up and Using a SHERLINE Lathe or Mill."

To really go into depth on miniature machining and using Sherline tools, I wrote a book called Tabletop Machining. This allowed me to go into a much greater level of detail than I could do with the instructions that are provided free with the machine. This book will give you all the knowledge you need to get started in machining. It includes many color photos of tools, setups and finished projects by other machinists. It would be useful for anyone getting into machining, whether they are using Sherline tools or not, although it will be particularly useful for the Sherline machinist. If you desire more information than that, we also offer a book by Doug Briney called The Home Shop Machinist's Handbook, which is another excellent introduction to the world of miniature machining. In fact, Sherline tools are used in all the setups throughout the book and it covers all aspects of machine shop work. Both my book and Doug's book give plans for simple but useful projects you can try to get started.

The ultimate book for any serious machinist's bookshelf is Machinery's Handbook. The 25th Edition contains 2560 pages of charts, formulas, articles and information related to machining and metalworking processes. If the answer to your machining question can't be found there, you're probably asking the wrong question. This book has been published and updated since 1914 and is based on an information database that goes back to the 1880's. It is the largest and most informative collection of metalworking information available anywhere, bar none.

Yes. Part of the design criteria for any change or advancement made on Sherline tools is that they still work with all the accessories we have made in the past. This also means that if you buy a used Sherline tool from a friend, all our new accessories will work on it, no matter when it was made. The only exception would be when an advancement eliminates the need for a particular accessory, such as the new DC motor's greater torque and speed range eliminating the need for the slow speed attachment or the new tailstock design eliminating the need for a tailstock spindle extender.

No. We have been making tools since 1974, and all our accessories will still fit any of the tools we have ever made and we plan to keep it that way. Though we will continue to strive to improve our tools and add to our accessory line as the years go by, you never need worry that the machine you buy today will be outdated. A good lathe from the 1950's is still a good lathe today, because the job of a lathe has never changed. We look at the functionality of our tools the way you might look at a pair of high quality needle-nose pliers. It does its job so well, there is no need to redesign it, and properly maintained, it will still be doing its job 100 years from now.

We machine and assemble all Sherline tools and accessories in our own factory in Vista, California, USA. Since we are in total control of our own production and do not import our machines from overseas, we are in a position to make sure we always have enough on hand to fill orders promptly. Orders are normally shipped the day after they are received.

By the way, we welcome visitors to the factory. Our office hours are Monday through Friday, 8 AM to 4:30 PM. All of our products are on display in the lobby for you to examine. If you call first and let us know you're coming, we can be sure someone will be available to take you through the factory and show you how our tools are made. Those interested in miniature machine tools usually find the big factory tools that make them fascinating to watch. These include a high powered laser engraver and impressive computer controlled lathes and mills. If you are ever in the North San Diego County area and would like to stop by, we look forward to meeting you.

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