7.5HP Three Phase Motor Conversion


Author Message
Dinges
Senior Member

Joined: 04/01/2008
Location: Albania
Posts: 510
Posted: 11:21pm 25 Sep 2008      

  oztules said  I now have a lathe chuck that attracts iron particles from everywhere, and a range of tools to match. The chuck is the killer though, gets particles stuck in the spiral race, and seizes it up....


Yikes. That sucks, Oztules. I have plenty of magnetized tools myself by now, every time I visit a machinist friend I take an assortment of screwdrivers, calipers etc. along to demagnetize them on a little gadget he has. Only to find them becoming magnetized soon after when I use them again near neos...

But a magnetized lathe chuck... Yikes. That's bad. I never had it happen to me (yet), I'm curious as to how it could have happened to you. The rotorshafts (the ends that stick outside of the case) aren't magnetic in my conversions, so they can't magnetize the chuck.

Seriously surprized here. Wonder what you exactly did for it to happen. I ask because that machinist friend now has my 10 hp rotor to turn down the epoxy casting. I certainly wouldn't want anything to happen to his CNC lathe. A magnetized toolpost could be easily remedied, I think (a bit like degaussing a CRT: move the support slowly away from the rotor as it is rotating in the lathe). But the chuck or other sensitive guides... you don't want them collecting metal particles . Makes cleaning impossible.

  Oztules said  I wound a 36 pole induction motor.... got hot and some harmonic crawl, but that was all. With 18 pole a much better crawl, but no real running, with 12 I got it to run reliably, but inefficient, with 8 we were away.

I wanted to ask you about this a few months ago, as I read about this in an old FL story of yours, with Zubbly mentioning something to the effect that it wouldn't work. At the time I wondered whether you actually went through with it and if so what the results were (I didn't find a follow-up post from you on FL but somehow it slipped out of my mind. I'm still toying with the idea of making a 24 or 36 pole conversion some day. I did bounce that idea off Zubbly but he wasn't thrilled; the reason he gave was that rewinding would be practically very difficult (inserting the coils in the slots, as the coil span is very small, only one stator slot); I think I could overcome that problem though; but if there are other, deeper reasons for why it wouldn't work... of course, induction motors are asynchronous whereas our conversions are synchronous... no squirrel cage rotor and slip... so it may not be a problem in conversions. Or ?Edited by Dinges 2008-09-27