The Pratt & Whitney swivelling vertical milling attachment was unusual in that, instead of being adapted to fit the standard slide rest, it was complete with its own compound slide unit and thus could be used on lathes fitted with were only equipped with the simpler types of hand-tool rest.
The slide carried an indexing unit, of the same collet fitting as the headstock, designed to hold small components whilst milling cutters, diamond laps or grinding wheels, held it the headstock spindle, were applied to them.
A separate high-speed cutter head, driven by an extra pulley on the countershaft and designed to allow work held in the headstock spindle to be machined, was provided as standard.

In common with other makers of precision lathes, Pratt & Whitney offered a toolroom-class milling machine which used either the complete headstock from the lathe, or an identical spindle assembly. More details of these machines can be seen here.