All materials tend to deflect away from the cutting tool when you are turning them on a lathe. This tendency is especially noticeable on long, slender parts and long pieces of bar stock, which makes it quite difficult to hold close tolerances. The best way to support a long part is with a center mounted in the tailstock. However, for one reason or another, this is not always possible. As an example, it may be a piece of stock that you want to center drill so that you can mount it between centers, or it may be a part where a center drill hole would ruin the looks of the part. Whatever the reason, a steady rest provides a means of supporting the part while it turns.
The Sherline steady rest has three adjustable brass blades mounted in a holder that mounts on the bed of the lathe. These blades can be adjusted to the diameter of the part to provide the necessary support. Another advantage of the steady rest that is often overlooked is the fact that work held in position by the rest turns concentrically with its outside diameter. This means that concentricity is assured when working near the steady rest, because, at that point, it must be running perfectly true despite imperfections in how it is chucked or centered at either end. The Sherline steady rest will accommodate any size part, up to 1.75″ (44mm) in diameter.
To drill a hole at the end of a long shaft, use a center drill in the drill chuck mounted on the lathe tailstock. The steady rest keeps the shaft from wobbling and assures that the hole will be concentric with the outside diameter of the stock.
NOTE: A steady rest riser block is now available which makes it possible to use the steady rest on the lathe with the headstock and tailstock riser blocks in place.