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Originally Posted by junkorgem

Hello again, I found a simple formula that may be helpful in your tool selection. It has to do with the relationship between torque and rated hp and rpm. I thought it was interesting, but then again it might be useless?
There is quite a big difference between a 1/3 hp motor operating at 15,000 rpm versus a 1/3 hp motor at 3600 rpm. You would have to agree. Just for an example, you cordless drill with hi and low gear, when you need to drive that big lag screw you put it in low, cause you need the torque. Although that is accomplished with gearing it is the same principle.
Here is the formula that I found. HP=TxN/C. T is the torque, N is the rpm, C is the constant (5252). Tranposed formula T= HPxC/N. This formula will show you that the lower rpm motor has almost 5 times the torque.
I have previously seen a post on this website that tells you what fpm is required for different compounds, with another formula for that. That would give you your target rpms with a given buff diameter, I think.
Has anyone tried a rheostat type control on an electric drill or die grinder? Probably just burn the motor up quick?

adding a rheostat would slow down the drill but it would not give it more torque and yes you would probably kill the drill on the long run