Variable Speed Motor Ideas

Follow Up. I got the Reliance motor (3/4 hp) and Ebay VFD. Everything worked on the test bench. Then the fun begins. I hooked it up to the lathe and it wouldn't turn an empty Head-stock spindle. I had to start fiddling withe the VFD parameters. Found out that the motor will only go up to 70 HZ. After that it slows down and stops going up to the 400 HZ. that the VFD produces. Had to increase the torque settings from 0. At one point the motor was running hot no matter what the settings or speeds. After two hours I got what I wanted and the setup works beautifully. 2 second start-up gives a slow gentle start. Control is locked to prevent reverse rotation. That keeps the chuck from spinning off the spindle. Motor stays at room temp no matter speed or load. My wife is in love with it. High speed turning down to low speed sanding almost instantly.
I am on the look out for another motor and will duplicate the setup on an old Delta school drill-press. It currently uses two belts and a movable pulley to change speeds. It's about 40 years old and still going strong.

I have potentiometers and switches on order from DigiKey to install on original control panel. I need to remote the VFD to keep it away from dust. Around $160-170 total cost which is not too bad considering what a decent 1/2 hp single speed motor costs. I haven't figured out how to install the tachometer pickup. There is no place to mount the magnet. I may have to make something to attach to the outer pulley.

Thank you to all who contributed. A successful conclusion!! Charles
 
Did you enter the motors RPM and Hz into the VFD, the VFD used these parameters to set the speed curve
 
mksj said:
You are limited by the motor frame size and shaft to something like a 3/4hp 3 phase motor. I would look into a motor/VFD combo as ther are some savings. Look at DealersElectric. The Teco L510 is decent for this application and simple to setup. A 1Hp motor is the next motor frame size. You should get better low speed control with the newer VFDs that run sensorless vector. You still may want to change to motor pulley size, so you can over speed the motor, typically 90Hz for this type of motor. Treadmill motor is an option, but matching up mounting, shaft size and getting the speed control working may be a bit more challenging.
https://dealerselectric.com/Package-P56X4109-and-L510-101-H1-U.asp
Click to expand...

Just a note on the Teco 510 - which I used on my 2x72 belt sander build.
There are some (software) settings you need to get right or you might experience some frustrating issues. I had a heck of a time with it until I came across some information provided by the mfg.

If you end up going with that unit I can try and find my notes on it.

Make sure you choose a motor with the correct max RPM for your application, you'll find 1725 rpm and 3450 rpm units out there.
I am guessing for the wood lathe you'll want the 3450 rpm...
 
You cannot run standard 3 phase motors to 400 Hz, at most I recommend 80 or 90Hz MAX. Below the motor base speed you loose Hp, so a reasonable speed range would be 30-80Hz. You would need an inverter/vector motor to go higher/lower and most of these max out at 5-6K and you loose a lot of torque. You need to adjust the VFD parameters to match the motor, this varies by the VFD brand/model. Typically you set the motor nameplate parameters such as base speed, poles, volts, amps/kW, etc., also some have an autotune for the motor. The VFD should be running sensorless vector mode if available. If you run a motor higher than it's base speed of 60Hz (US) then I often recommend going to a smaller motor pulley, in particular with a lathe.
 
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