Cross slide is mounted on the saddle, that, as its name implies, moves across the bed – and on top of that there is often a “Top Slide” or “Tool Slide” that is invariably arranged so that it can be swivelled and locked into a new position.
Very early lathes had a simple T-shaped piece of metal against which the turner “rested” his tool (all turning being done by hand) but when it became possible to move this “Rest” across the bed by a screw feed it became known, appropriately enough, as a “Slide-rest”. After the “Top Slide” became a more common fitting the term “Slide-rest” was not so frequently used – and the different functions of the two slides led to their specific names being more widely adopted.
When two slides are provided (or sometimes, on watchmaker’s lathes, three) the complete assembly is known as the “Compound” or “Compound slide” or even “Compound Rest”. Some makers have been known to label the “Top Slide” as the “Compound Rest”. The top and cross slide together should be termed as “the compound”.
The whole assembly of Saddle, Apron, Top and Cross Slide is known as the “Carriage”. Compound rest is an important of lathe.