variable frequency drive conversions

**mdhatter3** · Jul 7, 2019, 04:30 PM

I have a variable frequency drive motor from a treadmill. Can I change my drill press to use it? The drill press is a 5 speed bench
mount unit. Is it useful? Any ideas on how to do it? I thought I read an article about it but can't find it. Any help is greatly appreciated.

**jdurand** · Jul 7, 2019, 06:13 PM

do you have the controller for the motor?

**mdhatter3** · Jul 7, 2019, 08:01 PM

Yes I do. I have the rheostat, wires ,etc. If I can remove the belt drive (it is a round disc that is threaded on ) I am aware that I will have to machine an adapter to mount the coned pulley or use a single pulley of what size?

**jdurand** · Jul 7, 2019, 08:28 PM

Then this should work fine. If this is a brushed motor like most treadmills, be aware of brush life. Long for hobby use, not so much if it's constantly in use.

**Crusty** · Jul 7, 2019, 08:32 PM

I've read statements by many people that their treadmill motor conversions weren't successful because most of them are grossly overrated by the manufacturers.

**jdurand** · Jul 7, 2019, 08:42 PM

Of course, i should have mentioned the motor will be rated in Chinese hp. They take the Watts drawn by the motor and divide by 746 to get INPUT hp. USA motors are rated on OUTPUT hp.

Also, the Chinese rating is for burst power only, it will not sustain it.

For many uses this is ok.

**DIYSwede** · Jul 8, 2019, 07:56 AM

Originally Posted by jdurand

They take the Watts drawn by the motor and divide by 746 to get INPUT hp. USA motors are rated on OUTPUT hp.

Thanks, I didn't even know this was a (Chinese or other) practice -
AFAIK the wattage rating should be for continous duty (unless some other % DF is specified),
and HP/ kW output for on axle/ effective work. In the US and elsewhere.
Hence the efficiency of a motor will be "Input" divided by "Output" - averaging 90-95 %, right?

**jdurand** · Jul 8, 2019, 09:43 AM

Chinese motors, especially brushed ones are rated for "peak power". This is the same for other things like power inverters, I have one that proudly states 3000 Watts on the lid but in the instructions you find that's peak. Continuous is 800 Watts.

**Eaglewood** · Jul 8, 2019, 07:06 PM

I recently converted my 10 inch lathe to use a treadmill motor(brushed) rated at “2.75hp”. I used a pulley that allowed the motor to operate in the higher voltage/rpm range. I have threaded at 60 rpm with no problem and turned a 3.5 dia. Losing only 8-10 rpms. I used the motor control from the tread mill and wasn’t smart enough to separate it from the rest of the circuitry and added a tach.

**high-side** · Jul 8, 2019, 07:48 PM

Originally Posted by mdhatter3

I have a variable frequency drive motor from a treadmill. Can I change my drill press to use it? The drill press is a 5 speed bench
mount unit. Is it useful? Any ideas on how to do it? I thought I read an article about it but can't find it. Any help is greatly appreciated.

They work great for smaller drill presses. If you have stepped pulleys on the DP now, you could still retain them with the new motor so you have a "speed range" for each of the steps. This was an old beater w/ no motor I got for free and cleaned up and installed a DC motor and speed controller from a treadmill.