What is a Compound Rest?

A compound rest is a device found on a lathe tool. Lathes feature a rotating spindle used to mount a wooden or metal object. The spindle rotates the object, allowing users to shape or polish the item using a series of tools or attachments. This device is found in many woodworking shops, manufacturing plants, and industrial facilities.

The tools used to shape and polish objects on a lathe are located on a movable carriage that sits above the spindle. Many lathes feature programmable settings that automatically adjust the carriage to make precise cuts into the wood or metal. Lathes with a compound rest give users additional control options beyond those offered by the programming settings. The compound rest sits on top of the carriage, where the user can manually position it to the desired location.

While the carriage on a lathe can be set to a specific range of settings, the compound rest can be used to make even finer adjustments. For instance, most lathes can feed an object or move shaping tools only at specific intervals. Using a compound rest, users can set the tools to spots between the intervals to make cuts as needed. It also allows workers to adjust the cutting depth more precisely, as well as the radius or taper.

A standard compound rest locks into place on top of the carriage when not in use. Once unlocked, it swivels out of place in a full arcing motion so that tools can be positioned anywhere along the arc. By sliding the carriage electronically and swiveling the rest by hand, users are given a great deal of control over where tools are placed in relation to the object. Most lathes feature a protractor at the base of the compound rest, which helps with setting the angle.

Depending on the design of the lathe, the rest may lift up and down to various elevations above the carriage. If the rest is set at a fixed elevation, users must adjust the height of the cutting tools within the compound rest itself in order to change the depth and location of cuts made to the object. Many lathes also allow workers to modify the angle of these tools within the rest, which can be helpful for angled cuts or precision tapering. Finally, the tools themselves can be switched out on the rest to create exactly the right cut, or to polish or shape an object.