maybe not in this case, but from a history of machining, motors have made quiet and remarkable strides. original cone lathes for metalworking were driven by st

maybe not in this case, but from a history of machining, motors have made quiet and remarkable strides. original cone lathes for metalworking were driven by steam engines and a PTO driveshaft. aside from being ridiculously dangerous to operate, they had inconsistent results for tight tolerances. It wasnt unheard of for watchmakers to also find themselves as lathemakers in the early 20th century. Motor speed from PTO was largely not variable. During WWII motor speed was controlled with a clutch and transmission system, which arguably allowed for the type of finesse and control you need to run a shaper for a large tank engine, or a mill for certain explosives of the nuclear persuasion. older machinists handbooks will still reference your 'gear' when making a cut as a feed rate suggestion. old shapers still have a gearbox and shifter. along comes the VSM and its a game changer. The variable motor speed can control RPM maximum down to almost zero RPM. In the early 20th century, this simply was not possible. Previously if you wanted to change speed you had to park/reset the lathe and dial your tolerances back in. The way around gear speed change time was to intentionally oversize the part and take it to an automatic filer, but this wears down files and is only an option for certain manufacturers that care about the end product more than the tool wear (WWII again)