The lathe is among the lesser-known specialty power tools in a woodworking shop. By and large, most of us woodworkers don’t have one. That’s because the lathe is a specialty tool with certain specific machining operations that it’s designed to do. If we don’t do those operations, we have little use for a lathe.
But a lathe is a fascinating tool, able to do operations that no other tool can. While it might be possible to produce similar parts without a lathe, it’s impossible to produce parts that look just like those made by the lathe by any other technique. If we want those parts, we either need to have a lathe or buy those parts from factories that produce them just for woodworkers.
The parts in question are what are known as “turned parts.” This refers to the lathe operation, which spins or turns a piece of wood quickly so that the wood can be shaped by a series of cutting tools, basically various different-shaped chisels.
Two basic styles of parts can be made on the lathe, although an endless list of variations can be part of the results. One turned part category is the turned wood stiles used for banisters and chairs. The other is turned bowls and platters. While the same tools are used to create them, the process differs.
Please note: while I am breaking this down into only two categories, that’s merely talking about the methodology used to create them, not the finished project. For example. a vase and a bowl are shaped similarly on a lathe, even though their use differs.
Let’s Take a Closer Look
There are two different types of lathes out there: wood lathes and machinists lathes. The fundamental difference is the material they are intended to be used for. Wood lathes are designed for wood and other soft materials, while machinists’ lathes are designed to make metal parts. While you can work wood on a machinist’s lathe, you can’t work metal on a woodworking lathe. Working with wood on a machinist’s lathe is challenging and will go much slower than working on the right lathe.
The working part of the lathe consists of two “centers” in line with each other. Any wood piece being worked on is attached between these two, with the centers holding the piece snugly in place. The workpiece is then rotated around the axis created by the two centers, allowing various cutting operations to be committed to them. This produces a part that is symmetrical around the axis of rotation.
The two “centers” in the lathe allow turning the workpiece, with one being belt-driven by a motor. The other center is located on what is known as the “tailstock” and may or may not be used, depending on the work being performed. In the case of long pieces, the tailstock is always used to hold the part steady, but the tailstock is unnecessary for shorter pieces, such as bowls.
The workpiece is attached to the driven center (the one powered by the motor), known as the “headstock” securely, usually with wood screws. This ensures that it doesn’t become a ballistic object when rotated. All lathe operations are completed with the workpiece connected to the headstock spindle.
The most common lathe machining operation is removing wood from the workpiece with chisels. A movable tool rest is provided while being attached to the lathe bed. The tool rest supports the chisels during lathe machine operations to reduce the strain on the operator’s muscles and the tool chatter, which would accompany trying to hand-hold the cutting tools.
Once the material is removed, other operations, such as sanding and finishing, can also be completed on the lathe. While it is possible to do both of these off the lathe, sanding especially is much easier to complete on the lathe, allowing the turning of the lathe to provide the power in such a way as to retain the shape of the workpiece rather than using a power sander.
Necessary Specifications for Wood Lathes
If you decide you want a lathe, there are a few necessary specifications you need to take into account. These few specifications define the capacity of any particular lathe. As the lathe is a relatively simple tool, you can use the specifications to make buying decisions.
Distance Between Centers
The distance between the centers is the most significant between the driven center in the headstock and the live center in the tailstock. This determines the most extended piece of material you can work in that particular lathe. If you are turning a lot of table legs or balusters, you might need a longer distance between centers than someone making bowls would.
Of course, any lathe can work on pieces shorter than the distance between centers, even down to a few inches. I’ve known woodworkers who made wood pen bodies on lathes designed for turning 48” balusters.
Swing
The swing defines the largest diameter workpiece you can put in the lathe. The distance between the center and the lathe bed rails determines it. This distance becomes the radius in the circle of the “swing.”
This dimension defines the largest diameter workpiece you can put in the lathe. If you turn a lot of plates or bowls, this specification will be critical to you, as it will determine the most extensive piece you can do on that lathe.
Motor Size
Generally speaking, the larger the motor, the better. This isn’t just true for lathes; it is valid for all power tools. In the case of a woodworking lathe, the motor size will affect how much material you can take off on a single pass. A larger motor allows you to take more material off, while a small motor will mean you have to take more time doing your projects, as you’ll have to make shallower cuts to avoid slowing down the motor.
Speed Control
All lathes have some speed control, usually a belt with stepped pulleys. Some get a bit more sophisticated than that, with either electronic controls or a tapered pulley, which allows for constantly variable speeds.
When discussing speed, we customarily consider the revolutions the part makes per minute (FPM). But that’s not what’s important. What is important is the distance traveled across the cutting tool per minute, as measured in feet (FPM). Materials and cutting tools are matched for a specific FPM range.
It’s apparent that the higher the RPM, the higher the FPM. However, many people forget that the larger the diameter of the part being worked on, the higher the FPM. So, a larger diameter object, like a bowl, will need a lower RPM to give the same FMP as you would have with a baluster. The more complex the wood being cut, the lower the FMP you should have.
One Other Thing
In addition to these basic specifications, you want to pay attention to the overall construction of the lathe. These tools are put under a lot of stress when turning a piece of wood. A poorly designed or weak lathe will flex under that stress, something you can’t have. More than anything, you can tell how sturdy the lathe is by looking at the bed or rails. If they don’t look massive and sturdy, you will probably have a problem with your lathe.
For a lathe to work correctly, everything must be immovable except the rotating piece of wood. So, regardless of how the rest of the lathe looks, could you not buy it unless the lathe is solid? That way, you can be sure it won’t flex under the stress of turning the workpiece.