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PM 835S VFD

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wvnitroman

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#1
Is it possible to put a VFD on the 835 so it would be variable speed? If so, any idea how complicated it would be and the cost? Would it void the warranty?

Thanks,
Kevin
 

mksj

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#2
The primary problem is that the 835S is not available with a 3 phase motor, and getting a replacement motor that will fit may be challenging/expensive. The basic VFD installation is pretty much the same for most knee mills, so you can look at some of the 935 and 949 (or other mills) installs previously posted as to what is involved. They are simpler than a lathe install, cost wise without adding a motor you are probably looking at $600-700 range for a medium quality VFD in an enclosure with switch gear.
https://www.hobby-machinist.com/threads/received-my-pm949-and-pm1340gt.59421/


You can speak to QMT as to the warranty, typically they would cover the mechanicals but not the electrical once modified. If you purchased the VFD like the WJ200 from them, then it would come with the factory warranty (but I have yet to see one be DOA or fail).
 

wvnitroman

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#3
The primary problem is that the 835S is not available with a 3 phase motor, and getting a replacement motor that will fit may be challenging/expensive. The basic VFD installation is pretty much the same for most knee mills, so you can look at some of the 935 and 949 (or other mills) installs previously posted as to what is involved. They are simpler than a lathe install, cost wise without adding a motor you are probably looking at $600-700 range for a medium quality VFD in an enclosure with switch gear.
https://www.hobby-machinist.com/threads/received-my-pm949-and-pm1340gt.59421/


You can speak to QMT as to the warranty, typically they would cover the mechanicals but not the electrical once modified. If you purchased the VFD like the WJ200 from them, then it would come with the factory warranty (but I have yet to see one be DOA or fail).
Thanks for the response. From an expense stand point, if I would have to change the motor and install a VFD, I might as well buy the PM 935 TV to begin with. Plus the 935 is a Taiwan built machine so better quality over all.
 

wrmiller

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#4
Thanks for the response. From an expense stand point, if I would have to change the motor and install a VFD, I might as well buy the PM 935 TV to begin with. Plus the 935 is a Taiwan built machine so better quality over all.
I bought the 935TS 3-phase because with a VFD you don't need the added expense/complexity/wear a Reeves drive represents. That and a belt head runs whisper quiet.

On my mill, the belt stays in the middle slot most of the time. Only when I'm drilling large holes to I bother to move it. :)
 
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