a continuously running of the variable speed electric motor

variable speed electric motor ,As a rough guide though, a lightly loaded and infrequently used assembly, such as the dividing head,greater errors will be acceptable. On the other hand,a continuously running, heavily loaded assembly, will need to be as accurate as is possible.
speed reducer gearbox ,In this case it may be a situation for designing the assembly such that the worm gear diameter is chosen to produce a pitch that coincides precisely with one that can be cut on the lathe.