Variable Speed Motor Advice for KMG Grinder

[Busto]

There has been a lot of debate on what the best RPM is for a grinder. I use a 1750RPM as I can set the KBAC-27 to 2x speed. This gives me plenty of torque at lower speed and with a 5" drive wheel top end is around 4,600 FPM. This works good for me.

Ditto....with the 2x speed plenty of grunt on the low end and rarely will I turn it up for speed grinding since its not a contest to see how fast I can grind out a blade.

 

[catalytic]

There has been a lot of debate on what the best RPM is for a grinder. I use a 1750RPM as I can set the KBAC-27 to 2x speed. This gives me plenty of torque at lower speed and with a 5" drive wheel top end is around 4,600 FPM. This works good for me.

^^ This. This is what burr king does on their variable speed w/KBAC VFD models -- I talked to one of their engineers about it. Either way will work, but A 4-pole (17xxRPM motor) has a better towque spectrum at 60-120hz than a 2-pole (34xxRPM) motor has at 30-60hz. Go with 17xx RPM.

 

[logem]

If you can justify it, the best choice for a homeowner is to run a single phase 220V 20amp circuit directly to your workspace. This opens a lot of options for motors up to about 3.0hp, depending upon your choice of VFD controller.

Mike L.

 

[timgunn1962]

^^ This. This is what burr king does on their variable speed w/KBAC VFD models -- I talked to one of their engineers about it. Either way will work, but A 4-pole (17xxRPM motor) has a better towque spectrum at 60-120hz than a 2-pole (34xxRPM) motor has at 30-60hz. Go with 17xx RPM.

The graph is for 2HP motors, but the area in the triangle is the extra performance you get by using the 4-pole (1750 RPM) motor.