Has anyone tried a router speed controller on a belt grinder?

C

critrgitr

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Nov 16, 2009
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I am getting ready to build a 2x72 belt grinder, and would really like to have a variable speed controller on it. I can't afford the variable control units that come on most belt grinders. A carpenter friend suggested using a router speed controller that can be had for $50 instead. Here is the one i am looking at http://www.rockler.com/product.cfm?page=10760&tagem=rv I am planning on using a 1 1/2 hp 1725 rpm motor wired to 110, but have not purchased it yet. Has anyone tried this before? If it will run a 3 HP router why not a 1 1/2hp belt grinder drawing under 20 amps? If this won't work I am going with 3 step pulleys.

Thanks,
Brian
 
Sorry to say it won't work. It will burn out your motor very shortly.
Also they usually are not rated for the amp's required for a grinder motor.
 
Pooof!:(

For VS it's the basic choices are:

Single-phase AC you can used pulleys, different-size drive wheels, or perhaps an elaborate mechanical transmission drive (which can sometimes be found at surplus). ---all a pain in the butt, except the tansmission option which could be cool, but will certainly require some fabrication to adapt if you're lucky enough to find one. All-in-all, a sub-optimum situation for most.

Single-phase DC with variable speed controller. A great option, but generally expensive once you get to bigger hp (over 1hp) and getting the right combo, (like a 2 hp with 3600 rpm) comes pretty dear.

Three-phase with VFD The best choice for most of us. The 3-phase motors are generally cheaper than either single-phase AC or single-phase DC in comparable HP/speed ratings. The VFD can be used to produce the 'third phase', allowing you to put 220V single-phase in and get 220V three-phase out (just be sure to buy a VFD about 1/2 "bigger" than the HP rating of your motor if you're doing this, because creating that third phase 'derates' the VFD by 1/3 on paper. In practice, it's closer to 1/2, so unless you like constantly resetting the 'breaker' on the drive whenever you lean on it a little, just go with a bigger VFD.)

Naturally, the biggest advantage is that you can run bigger HP, variable speed for a lot less money than the DC option!:thumbup:
 
Thanks for the info. I figured thats what the answer would be. Looks like I will be going with step pulleys for now.
 
Nobody has said this so I'll clarify:

Motors that can be controlled by a rheostat are the type that are not locked to the line frequency. Things like routers, grinders, saws and even shop vacs. These are generally high speed motors.

Most of the big motors like we're talking about are a design that are locked to line frequency. So, lowering the volts (by cutting off the tops and bottoms of the waveform) is going to raise the amp draw and eventually burn things up. Like in a brown out. And, ironically, not significantly change the speed. You'd have to change the hertzs to do that, which is what a VFD does.
 
Last edited:
jaymeister99 said:
Do you think this would work on a Craftsman 2x42 belt grinder? It basically a modified bench grinder.
Click to expand...

Is it a fixed speed motor? Something like 1700 or 3400 RPM would be a give away...




Most likely it is, so no it probably won't work. sorry.
 
Just a voice of logical deduction here;
If there was a cheap and easy way to make most tools VS, don't you think they would come that way?????

The reason they don't is because there isn't.
 
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