7.5HP Three Phase Motor Conversion


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SparWeb

Senior Member

Joined: 17/04/2008
Location: Canada
Posts: 196
Posted: 06:42pm 26 Sep 2008      

[quote]...I now have a lathe chuck that attracts iron particles from everywhere...[/quote]

That must be awful. For another way to de-magnetize your chuck (maybe) you could try to find an aircraft parts inspection company, particularly one that inspects helicopter parts. Large operators often equip themselves to do the inspetion in-house, too. They would have rather large equipment for "degaussing" parts after their magnetic particle inspections. A regular lathe chuck would fit in them. Show them some pictures of the crazy stuff you do - guys around here would help you out for free if you asked.

I can propose a way that the lathe chuck would be magnetized. While holding the rotor in the lathe, did you install or remove magnets from the rotor? If so, the unbalanced fields would leave extra field lines from one pole that would spread into space, and into the nearest big hunk of metal they can find. The circuit completes through the jaws of the chuck, to the shaft, and back into the rotor. The tailstock and toolrest may also be magnetized.

Earlier, when I was experimenting with the cog, and had only a couple of magnets on it, I had a lot of trouble inserting the rotor into the housing. It was sticking magnetically to the end shells. I realized that I had placed all of the magnets N pole out. The ends of the shaft were big S poles! The loop must be closed between all of the rotor's poles, or the lines can "wander".

The rotor on my bench is complete, but there still seems to be some stray field lines because I can pick up washers and screws with the end of the shaft, now. The rotor may not be keeping the lines inside the laminations, or it may have something to do with putting 4 inches of magnet on a stack of laminations only 3.8" across.


Steven T. Fahey