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Col Mckee
11-05-2006, 06:59 PM
I'd like to buy a large (3hp) grinder and run it on single phase. Is this doable without using a rpc (ie using some sort of solid state box?) Three phase grinders are relatively inexpensive but I'm not interested in taking up a whole lot of space with a rpc. What I'd like is to turn on a switch and go. Thanks...

timh
11-05-2006, 07:21 PM
Try a static converter use one on mine works fine.

Mcgyver
11-05-2006, 07:22 PM
I've been told the phasematic type (not rpc) will not work properly without a load. I've used them with a mill or lathe and with the transmission they're ok, but you loose some power. Been told not to on a table saw or grinder, something without a load because the lack of balancing is very pronounced. still haven't got around to making a rpc, but i think thats the best route to go

Optics Curmudgeon
11-05-2006, 07:34 PM
Static "phase converters" are really just a start capacitor and potential relay, the motor is actually running on single phase once the box gets it spinning. Shouldn't care whether the motor has a load or not. The same circuit is used to start most rotary converters.

Joe

Your Old Dog
11-05-2006, 07:35 PM
Out of curiosity have, have you ever used a nice 72 inch belt grinder, some call'em snag wheel grinder? They are very flexible in use and can chew up a lot of steel in a hurry. Knifemakers use them and you got a tremendous assortment of grits to use. Belts change in a matter of seconds. Worn out fine grit belts are used inside out with buffing compound for mirrior finish. I had a 2HP unit and it took most anything I could shove in it. Just a thought but you know your needs better than I.

Here's an outfit that is pretty popular with the knifemaking crowd. I'm getting ready to build one of these for my shop. Have nearly all stock accept the motor.

ray....