An American Watch Tools Company drawing from about 1890 showing a section through the headstock of an early WW lathe. The unit consisted of the main "frame", a Spindle, a Rear Adjusting Bearing, a Bearing Adjusting Nut and the Headstock Bearings themselves. All the bearing surface were hardened, ground and finally lapped to a perfection of fit.
The Headstock Bearings were pressed into bored and honed holes in the casting - the Front Bearing having the same angles of 3 and 45 degrees as the Spindle Nose. The Rear Adjusting Bearing was a sliding fit on the spindle - and kept from turning by a key pin; its two angles of  3 and 45 degrees matching the angles formed on the "inner" Headstock Bearing. The single Adjusting Nut screwed onto a very fine thread on the end of the spindle.
Like many other makes of watchmaker's lathe, close-fitting dust caps were snapped onto flanges at each side of both bearings.

A drawing from 1950 of the headstock fitted to the Magnus lathe - with the same 50mm centre height as a standard WW, but with a collet capacity of 0.3125"  (5/16" - or 80 metric) compared to the 0.1969" (50 metric) of the original.
The assembly was essentially the same as the one above but the headstock frame was more massive with a greater thickness of material around the bearings. On this model dust caps were fitted to the outside of each bearing - but not to the inside faces.

Combination Tailstock with patented rack-feed barrel. The patent (No. 1,168,063) was applied for on June 4, 1913 and granted on January 11, 1916.

End section through the Combination Tailstock.

End elevation of the Combination Tailstock.

Below: the improved slide rest assembly with an easily-adjusted tool holder