: I would like to control the speed of a 1750rpm washing machine motor im using in a home-made grinding machine : electronically(an scr circuit perhaps)as it is now, im using a 1" pully on the motor,and a 14" on the spindle,which : turns at about 170rpm,would like to vary the rpm,without using a system of pully's,from 0 to 100rpm,anyone know : where i could locate an ac motor controller,or schematic for one? : Thanks : stevec.

Thanks Robert,Rick,Dianne for your comments. O.K so electronic speed control isnt a good idea ,i guess i will stick with using pulleys to control the rpm,i know that there is a range of different rpm to grind and polish,the machine i have now runs at 170 rpm and can only be used for grinding,in fact this is too high an rpm,i think that anywhere from 40 to 120 would be optimum for grinding,and 5 to 20 for polishing. I have made over 20 mirrors from 4 to 16 inch,most of which were machine ground(170 rpm) and hand polished/figured.i plan on making many more and much larger optics,and this is why this old man needs a machine,my back hurts,my hands hurt,in fact i hurt all over!........stevec(THE AMATEUR glass pusher)