By the late 1930s and like Cataract, their long-time rivals in the precision bench lathe business, Ames were forced to utilise their 40 years of experience in making lathes and millers (and shapers, slotters, automatic gear cutters, micrometer dial gauges and other precision products) to modern their machines. Out went cumbersome and expensive overhead countershafts with their flapping, exposed belts and in came neat, self-contained stands with V-belt drive, speed-change gearboxes and even mechanical variable-speed drive systems. Because of their customers' investment in tooling and accessories it was impossible to make changes to the size or shape of the bed but the headstock of both makers lathes was a prime candidate for modification and, with the advent of super-precision ball races (called at the time "anti-friction" bearings) it was not long before these were being offered in place of the high-class plain bearings that had been in use since the 1880s.
Ames first modified the No. 3 lathe to accept ball races in the headstock but left the rest of the lathe, including the flat-belt pulleys, large unmodified, although it was offered on a rather more compact, self-contained stand, 
The next development of the lathe, the 43/8" centre height by 171/2" between centres EH3, was to be its final evolutionary form and, whilst the bed again remained unchanged, the headstock was completely re-designed and strengthened so that it completely enclosed the 1"-bore,  hardened and  ground alloy steel spindle that ran in the same type of high precision, pre-loaded, grease-packed ball races as before. The final dive was by twin V belts that could only pass up through the base of the headstock, so forcing the lathe to be mounted on an under-drive stand.  The makers claimed that, for all its precision and great accuracy, it was possible to dismantle and reassemble the headstock (to change the belts) in only "a few minutes."
The only stand listed by the makers was designed as an integrated unit complete with a drive system, switchgear, light and storage. At 36" high,  54" long and 30" deep it stood on heavy section pressed-steel legs topped by a linoleum covered wooden top edged with strips of polished maple. A metal-faced board  to hold the faceplate, 3-jaw chuck and a set of collets was fitted into the right-hand rear corner of the top surface and a light unit mounted behind the headstock on the left-hand side. Underneath the top was a mechanical variable-speed drive unit, bolted to the end of a 1/2 hp DC or AC motor and controlled by a flexible drive turned by a handwheel. Unsurprisingly, rather than wrestle with the complexities of building their own under-slung  multi-speed V-belt drive countershaft,  most customers chose to buy the lathe on the ready-to-run stand.