Complex sentence: The workpieces machined on a jeweler's lathe are metal, jeweler's lathes can be used with hand-held "graver" tools or with compound rests that attach to the lathe bed.
Split into simpler sentences: The workpieces machined on a jeweler's lathe are metal. Jeweler's lathes can be used with hand-held "graver" tools or with compound rests that attach to the lathe bed.