Are you familiar with the variable pulley like used on ShopSmith machines?
The front panel knob moves the pully sides apart and together, changing
speed. Perhaps you can find a used head or just order a pully.
> From: Dave Williams <email@example.com>
> To: shop-talk@Autox.Team.Net
> Subject: Re: speed control
> Date: Tuesday, January 20, 1998 1:26 PM
> -> It gets worse. You also need a DC motor that will run about $400 for
> -> 1hp. The prices in Grainger's are, unfortunately, hard to beat.
> How is it I can buy a 3/4hp variable speed drill for $75? I know the
> power is overrated and the service factor stinks, but I don't understand
> what makes one type of application cost so much more than another.
> -> How about using 4 or 5-step pulleys? Not as cool, cause you gotta
> -> stop and move the belt, but it's WAY cheap.
> I'm already using step pulleys. However, I need to vary the speed
> somewhat in between the ranges. And it's not practical to stop while
> doing it. I don't need a *lot* of speed adjustment, but I have to
> compensate for load changes.
> I thought about going to a 2hp, 3400 RPM motor, geared down to 100
> RPM, and not worrying about speed changing with load... but by the time
> it saw enough load to worry about it'd probably rip the stones right off
> the holders.