View Full Version : Motor Help

Mike Turner
10-16-2010, 6:52 PM
I have a 1/2 hp....1750 rpm motor on an old Craftsman lathe. The model is 113.12790. It has started getting hot and hums when I turn it on but if I spin the shaft or do a light pull on the belt it comes..The shaft size is 1/2" on...

I have a 1 1/2hp 3450 rpm motor model 818320...The shaft size is 5/8"....I would have to buy a step pulley to fit the 5/8 shaft but would this work ? The step pulleys on the 1/2 hp one begin at 2 in and go on up to to 4 in. It works good and a friend gave it to me so I have nothing in it....What size step pulley should I use to get it to work like the 1/2hp one ?? Thanks !!

Or what do I need to do to the 1/2hp one ??

David Christopher
10-16-2010, 6:58 PM
Mike, it sounds like your 1/2 HP motor needs a start capacitor...that would be the easiest route

Ed Aumiller
10-17-2010, 9:20 PM
Since the replacement motor is close to double the speed, then the replacement pulley would have to be 1/2 the size. So you would need a step pulley starting at 1" going to 2". Might be kinda hard to find that size. Another problem with a lot of motors that won't start is simply the start contacts on the end of the motor are corroded and need cleaned. Take the end of the motor off opposite the pulley end and burnish the contacts and try it again. Good luck.

Mike Henderson
10-17-2010, 9:41 PM
Yep, it's almost certain your capacitor on the 1725RPM motor is bad. They're pretty cheap and easy to replace. Try that before replacing the motor.