10EE pulley sizes and RPM

[Cal Haines]

I ran my round dial 10EE on the DC drive for years. It had a LOT more than a 3.5:1 speed range, or 690 to 2400. that would be a terrible performance out of a DC drive. My memory of 20 years ago, had it more like 8:1.

Sorry, do not have actual data or facts. Just really skeptical about the above statement. The 10EE was a wonderful machine with the DC drive, right up till it died. I am getting a 10:1 speed range or 400 to 4000 rpm out of the VFD 3 phase combo. But it does have less torque at low Rs than the DC drive. Approximately the same speed range though.

I didn't say that it went from 690 to 2400 RPM. 690 RPM is the "base speed" of the motor, which is what you get if you apply the full 240 VDC to the armature and full voltage to the field (usually 115 VDC). Above base speed, the field voltage is reduced and the motor speed increases up to 2400 RPM (at the output to the motor). Below base speed, the field voltage is at 100% and armature voltage is reduced. The MG drive system allows you to vary the motor speed from about 30 RPM minimum to 2400 RPM. There's a 6:1 back gear unit that can be shifted in to further reduce the speed. My machine can turn at any speed between about 8 and 4000 RPM, using the back gear as needed.