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PM932VFD upgrade
- Thread starter Rich Berg
- Start date
I'm very please with the upgrade so far, the drive has been programmed to accommodate the original forward and reverse switch on the mill.
I have the acceleration set to 2 seconds now and I can for the first time comfortably power tap, also in the past the original motor would start so hard that the drill chuck would let go of the tool.
I have the acceleration set to 2 seconds now and I can for the first time comfortably power tap, also in the past the original motor would start so hard that the drill chuck would let go of the tool.
Very nice , I see a three phase swap on my mill in the near future
- Joined
- Jul 30, 2017
- Messages
- 635
Hey you..
I always appreciate people going above and beyond... Ya know... taking the time to test these mods, work out the bugs & fix them before I spend my time and hard earned cash installing them my self.
Love it very nice job Sir...
I asked Mike at PM about doing this exact same thing a couple weeks ago to a PM-932, If I remember correctly he mentioned or what may need consideration was the PM-932 doesn't have hardened gears, and spindle bearings may not be designed for higher RPM's
I asked because the PM-727V is a variable speed gear head but I like the weight and table size of the PM-932, Just a heads up and maybe something to keep in mind.
Mike.
I always appreciate people going above and beyond... Ya know... taking the time to test these mods, work out the bugs & fix them before I spend my time and hard earned cash installing them my self.
Love it very nice job Sir...
I asked Mike at PM about doing this exact same thing a couple weeks ago to a PM-932, If I remember correctly he mentioned or what may need consideration was the PM-932 doesn't have hardened gears, and spindle bearings may not be designed for higher RPM's
I asked because the PM-727V is a variable speed gear head but I like the weight and table size of the PM-932, Just a heads up and maybe something to keep in mind.
Mike.
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HI I will run the motor at the same speed of the original. the motor needs to cool itself so slow speeds at the motor will be short. I am also working on an armature shaft grounding brush to protect the bearings. no room at the drive end so it will be at the fan.
I have a very poor drawing of the adaptor, if anyone is interested in it maybe if you have cad a drawing can be made. also the wiring and programming for that drive can be available.
the nice part of the drive it comes with the program you need, just a few changes must be made to the D inputs.
I purchased the VFD and the motor at Amazon for close to $300.
Rich
I have a very poor drawing of the adaptor, if anyone is interested in it maybe if you have cad a drawing can be made. also the wiring and programming for that drive can be available.
the nice part of the drive it comes with the program you need, just a few changes must be made to the D inputs.
I purchased the VFD and the motor at Amazon for close to $300.
Rich
- Joined
- Jun 22, 2023
- Messages
- 728
if you limit the VFD to 60hz the grounding brush my not be needed, but have you thought of milling out space in the adapter plate for the brush?
have you thought of adding a fan on top of the stock fan housing to add air for lower speed operation?
Hi, as you probably know the VFD is always chopping a set DC voltage rectified from the line therefore to make a 60cps current developed with the motor it still must use PWM that causes the eddy currents, so there will still be arcing through the bearings to ground (EDM).
Most of the time I will be using at around 1750 RPM, don't think I will need an extra fan but I will watch it.
I finished the grounding brush yesterday, can't hurt.
Thanks for your interest.
Rich
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- Jun 12, 2014
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A reasonable speed range for the motor would be around 30-70Hz, I wouldn't want to run the gear head above 2000 RPM given the quality of the gears and bearings. You should not have cooling issues, as the TEFC motors cool decently down to around 20Hz and very unlikely you would be running a manual lathe continuously under load for any extended time. There have been a number of VFD conversion of the PM-932, a few have also used TENV inverter/vector type motors and converted them to belt drive. The limitations seems the quality of the gears/bearings as well as the seals going. I ran synthetic gear oil in a previous gear head mill that I had, and the improvement was significant in that there was less foaming, ran cooler/quieter as well as higher top speed (assume less frictional loss). I have yet to see/hear of motor bearing erosion occurring due to VFD use awith 220V motors, I wouldn't worry about adding a shaft grounding brush, on particular for occasional use manual lathe. Not aware of any VFD machines with factory installed ones on smaller mills and lathes. I did do a few VFD/motor installs (if I recall WEG motors) that came with a factory grounding brush on the shaft. Bearing/insulation issues due to VFD's seem to be more of an issue at 400+V and longer cables.
- Joined
- Jun 22, 2023
- Messages
- 728
I typically install dual insulated bearings and a single aegis grounding brush on all of my large motors (1000hp and above) at 4160v as well as DV/DT filters for long runs. but that would be overkill for this application.
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Hi I too used Agis for motors 25hp to 800hp and also added DV/DT filters to VFD's with long lines. we had at least 120 VFD'S at one of the facilities.
I don't think this applies to a hobby mill, we changed a lot of bearing with EDM damage, the motor size doesn't seem to matter as much as length of line.
I don't think many hobbyist's would have any idea what the root cause of their bearing failure. "maybe just a poorly manufactured one"
Hope this helps someone.
Rich