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Adding a VFD to a PDM-30 mill

Brian H

Brian H

Super User
SO, while I'm waiting for parts (not a good thing to sit idle, I come up with bizarre ideas) to put my mill back together I was pondering the advantages/disadvantages of adding a VFD for speed and forward/reverse control on my mill.

It is a PMD-30 with a 220v single phase motor. I am "electrically challenged" and know just enough to get myself in trouble...

Is this even possible? I like the idea of having a bit more speed control without constantly changing the belts, but, I'm not sure if this is even reasonable to consider. Having the ability to have forward/reverse would be awesome. (I did wire this into my mini-mill but am a bit daunted by the mass of electronics on the big mill).

Have any of you guys done this? What are the pros/cons? Any suggestions are welcome.
 
@David_R8 and I converted our RF30s to VFD. Love it, haven't changed a belt since. You're going to have to replace the single phase motor with a three phase motor. My upgrade didn't cost all that much. $50 for a used 2 HP 3 PH motor and $100 for an Amazon VFD.
 
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I think I'll put this on the back burner for a bit. I'm just not prepared to pull off a brand new motor and replace it right now...
 
YYCHM said:
@David_R8 and I converted our RF30s to VFD. Love it, haven't changed a belt since. You're going to have to replace the single phase motor with a three phase motor. My upgrade didn't cost all that much. $50 for a used 2 HP 3 PH motor and $100 for an Amazon VFD.
Click to expand...
I'm curious what rpm range do you have with one belt setting? I've flipped on my belt settings a couple of times but usually have about 1300 rom as max speed with out changing belt configuration.
 
DPittman said:
I've flipped on my belt settings a couple of times but usually have about 1300 rom as max speed with out changing belt configuration.
Click to expand...

About the same, 1250 RPM with the VFD limited to 90 hz max and the belts set mid range (700 RPM at 60 hz).
 
DPittman said:
I'll have to check on that, I could be wrong. I've switched my belts around recently and maybe I'm confused o_O
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Ya I was wrong (what's new?) The typical belt arrangement I've been using gives me a 254-1527 rpm range from 20hz tob120 hz. At 60 hz it is running about 765. That range seems to cover alot of what I do (so far).
 
Hi Craig, (or anyone who has the knowledge ;) )
Can you please tell me which motor you used on your PDM-30 VFD conversion, I am looking to also follow this path, and it would help me to know the type of motor required (I know I need 3 phase motor, at least 2hp with a VFD 240v 1 phase input, to 240v 3 phase output) but I am more interested in the kind of motor mounting frame/bracket needed and length of the shaft, so it fit the pulley correctly. I have not unmount my motor yet, so to make measurement would required me to move the whole unit from the wall, which I want to avoid for now.
Any other valuable info would be appreciated :)

BTW, I saw the TECO VFD model L510-202-H1-U that might work, what do you think?

Thanks for your input.
 
slow-poke said:
3-phase motor arrived, very well packed!
View attachment 40662View attachment 40663View attachment 40665View attachment 40664
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FWIW,
I converted both my old and latest mill to VFD. The blue motor is what I'm using on the latest one 1.5HP. Paid $113 for it from Lenmark. Sold the old original one for $100. So upgrade cost was negligible. If you keep your eyes peeled these 1.5-2HP motors sell for peanuts. Smooth and quiet Variable speed - priceless
newMotor.jpeg
 
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slow-poke said:
FWIW,
I converted both my old and latest mill to VFD. The blue motor is what I'm using on the latest one 1.5HP. Paid $113 for it from Lenmark. Sold the old original one for $100. So upgrade cost was negligible. If you keep your eyes peeled these 1.5-2HP motors sell for peanuts. Smooth and quiet Variable speed - priceless
Click to expand...
Just like slow poke posted. Keep an eye out for them and talk to people. I got my 3 phase weg motors from a friend, who's company was binning them.

I just finished the vfd install on my lathe today so that's a big win. Cost me $65 bucks for the vfd off amazon, black Friday deal. I got another one for the RF30 project. Just a matter of wiring up the lathe as it was already 3 phase. The mill I just have to pull the stepped pulley off, put it on the 3 phase motor and rewire it and it should be good to go as well. The wife's bugging me to spend time with her during the holidays so be in the new year when I get the mill sorted out.
 
djberta said:
Just like slow poke posted. Keep an eye out for them and talk to people. I got my 3 phase weg motors from a friend, who's company was binning them.

I just finished the vfd install on my lathe today so that's a big win. Cost me $65 bucks for the vfd off amazon, black Friday deal. I got another one for the RF30 project. Just a matter of wiring up the lathe as it was already 3 phase. The mill I just have to pull the stepped pulley off, put it on the 3 phase motor and rewire it and it should be good to go as well. The wife's bugging me to spend time with her during the holidays so be in the new year when I get the mill sorted out.
Click to expand...
I'm quite curious about your VFD driven lathe, please share some details:
What size lathe?
What size motor?
Does your lathe have a slow speed (I think they call it a back gear), or are you just relying on the low speed torque of the motor?
Does your VFD have the SVC feature?
How do you find the power/torque at really slow speeds?
 
slow-poke said:
I'm quite curious about your VFD driven lathe, please share some details:
What size lathe?
What size motor?
Does your lathe have a slow speed (I think they call it a back gear), or are you just relying on the low speed torque of the motor?
Does your VFD have the SVC feature?
How do you find the power/torque at really slow speeds?
Click to expand...
Lathe is a Standard modern ultilathe 9 inch. The motor is a 1/2hp 208 3 phase motor. So not a very large load at start up. So far I have only run the vfd at 60hz to check operation after I put the lathe back together. I cut a small piece of steel to just test how it would handle some torque. At about 20 hz it runs ok, but that would be the lowest I would run the vfd. Still need to work on the settings a bit. I sized the AT5 vfd to 1.5kw to compensate for the single phase to 3 phase. No SVC, its a straight cheap inverter. So just voltage and frequency control. I do expect it should run for some time, as the AT series seems to be ok quality. Time will tell. Teco or Schneider would be better budget options for quality. For a more serious application I would look at ABB, Weg or eaton drives. But for a hobby lathe level I think the cheapo amazon units are an option.
 
djberta said:
So not a very large load at start up.
Click to expand...

Might not be huge compared to other lathes, but startup is generally when a lathe sees its biggest load. The motor has to wind up a whole slew of gears, a few long screws, a heavy chuck, and also whatever big heavy mass might be in the chuck jaws.

Lathes see the biggest loads starting and powered stopping. Waaaay more than a mill.
 
Susquatch said:
Might not be huge compared to other lathes, but startup is generally when a lathe sees its biggest load. The motor has to wind up a whole slew of gears, a few long screws, a heavy chuck, and also whatever big heavy mass might be in the chuck jaws.

Lathes see the biggest loads starting and powered stopping. Waaaay more than a mill.
Click to expand...
It's a good point, a few days ago I was searching BLDC motors and the one I'm upgrading my lathe with actual comes in two varieties based on if it's used in a mill vs. lathe. They look identical and I asked the manufacturer what the difference is, but they have not responded. I think the lathe version might have a braking resistor kludged onto the control board. That would make sense because of the back EMF when spinning down with a heavy load.

Fortunately my leadscrew is not driven from the spindle motor, so that should help a little bit.
 
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