grinder motor suitability question

V

Von Gruff

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Nov 24, 2014
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A friend is starting a 2x72 grinder build and the question of a motor came up. He has a 1 hp 3450rpm from a Sears Craftsman table saw he would like to use so the question is - is it suitable for the grinder and if so what size drive wheel would give the best results.
 
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What kind of setup is he going after? Step pulley? Direct drive? Personally, I think 3450 RPM is too fast for MOST grinding, other than hogging on coarse grit belts. 1725-1800 RPM would be more ideal. Also, 1hp is on the absolute low end for power, especially with a 3-4 wheel setup. A belt/pully drive train will pull out even more of that power and the grinder will likely stall a lot.
Is it an open frame motor? That would be another point against it.

I'm not saying he can't use it, but it'd certainly be far from my first choice.

As for drive wheels, 4" is a pretty standard size, and widely available for $35 or $40.
 
Thanks Drew. I sent him the link to this thread so will chat with him on that recomendation. I know he has a 1 hp 1750rpm motor but it runs the wrong way so would need a jack shaft to get the belt running in the right drection as the polarity is not reversable. Would the increased torque of the 1750 motor be more suitable. My own motor is a 1 hp (4 pole) 1440) motor and it makes for a good comproise as far as SFPM speed goes, or at least it works well for all that I need it to do.
 
Is it a capacitor start motor? If so, I'd think that 1750 rpm motor could be wired to change rotation?

Ken H>
 
If it's from a sears table saw, you can't trust the rating on it.


It's an open frame motor, I'd bet your $ on that.
That makes it unsuitable.
 
Thanks for the replies. Have passed the link to this thread on to him so will see if he can put the 1750rpm motor on the other side of the belt so that it turns the correct way. Just because most motors are on the left hand side of the belt is there any reason not to have it on the right side, whether it is direct drive or through a transfer shaft??
 
If you have the space on the right side of the machine, you can certainly mount the motor from the right, though if you're wheels are also on that side, it can be somewhat inconvenient to install/remove your abrasive belts. You could also just make a completely "left handed" machine where the wheels are all on the same side to correspond with how the motor is mounted. There's not really a rule that says they have to all be one one side or the other.
 
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