1750 RPM vs 3500 RPM

1750 RPM or 3500 RPM

  • Total voters
    15
I run my 1750 with a 4" drive from 3 to 180 hz. It starts to get a little coggy below 6 but we actually use it at 5 a lot.
 
The only comment I have, is I have a 3500rpm motor and never run it past full speed (60 Hz) with a 5" drive wheel.
 
I think where people get caught up is HP, It’s just a number. Problem is HP does not grind knives torque does. As you step drive wheel up or down your torque fallows suit. Torque is just how much force the motor can push the belt. It’s not rpm dependent it’s just force. HP is a calculation of how fast it can do that torque. HP=RPM x Torque(ft/lbs) / 5252(radians). It’s just a measurement of work done over time. Kinda like how watts is a measurement of energy over time.

So with all that said, what’s most important to us is torque. This is because we are running a friction load. We pick an rpm range we need and then add the amount of torque we must have.
 
You are absolutely correct JT - "IF" I were doing heavy grinding in the 1500 to 2,000 SFPM range I'd want a 1750 rpm motor for sure. For me, down at the slower belt speeds I'm using fairly light pressure. When I want to use heavy pressure I'm wanting to remove LOTS of material and have the speed cranked up to 3,000 to 4,000 SFPM speeds. That's where I need my max torque. Either a 1750 or 3500 rpm motor is going to give pretty much the same torque at max speed. That's why I've said "for me", I'll never know the difference between the two motors, except when moving and purchasing.

I do have a 1750 rpm motor on a disk grinder, which never gets run past 1750 rpm anyway.
 
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