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MVal 08-07-2016 05:22 PM

Replacing generator field windings

My 30-31 generator recently overheated (250+ deg) and the field pole insulation is scorched and mostly missing so am considering replacing both field poles and anything else to put it back into usable condition. But before I spend money on the field windings etc. and get involved in the project wanted to know if anyone has some experience in removing the screws holding the poles in place as they look pretty securely in place. Have considered using a rachet with a screwdriver attachment in a drill press but thought maybe someone had a better idea and more experience.

Y-Blockhead 08-07-2016 05:36 PM

Re: Replacing generator field windings

I recently replaced the field coils on two starters (converted them to 12v) and had to drill out the screws (same screws as generator) and install new screws. The bevel on the screw is at a different angle than the bevel in the starter or generator case (~1) so they are basically an interference fit and just about impossible to remove without destroying the screw anyway. Once you drill the head off you can remove the threaded part by hand.

I broke two Snap-On bits using an Impact Driver with no joy. Much cheaper to replace the screws. :p:p

Synchro909 08-07-2016 05:41 PM

Re: Replacing generator field windings

Try a little heat on the head of the screws. Heat them till red hot with an oxy torch, allow to cool and undo. If they are still tight, I'd use an impact driver to move them. A drop of penetrating oil will help.

montanafordman 08-07-2016 05:58 PM

Re: Replacing generator field windings

I ended up using my wire welder on a couple generators I'm rebuilding. I welded along the slot in the screw and built it up above the screw along the slot high enough to grab with a pair of vice grips and turn them out. The heat, plus the leverage gained from grabbing the built up weld bead made breaking the screws loose much easier. Then I replaced the screws.

Of the two generators I'm working on - I assembled one with good original parts. It motors beautifully but I have not yet tested it on a car. The other I have a new armature and field coils for and I can't seem to get the pole shoes tight enough not to interfere with the armature. Even tightening the pole shoes with bolts wont seem to cut it. I may have to take it to a generator shop to see if they have any better method of tightening the pole shoes and forming the field coils around the shoes and contouring to the inside of the generator case.

tbirdtbird 08-07-2016 06:37 PM

Re: Replacing generator field windings

do a search i have described a very easy method for removing these. it is similar to the OP's ideas of a bit in a drill press.
they are supposed to be in there tight; the pole shoes want to be tight to the case

Herb Concord Ca 08-07-2016 06:48 PM

Re: Replacing generator field windings

Y=blockhead has the rigth idea, that how I do both generators and starters. what is left in the pole piece you can remove with you fingers!

For Montanafordman, new field coils need to be formed to both the case and the pole piece for them to fit correctly for armature clearance. I also use C-clamps to hold them in place while it tighten the screws.

RonC 08-07-2016 07:15 PM

Re: Replacing generator field windings

Bring it to a local starter/generator rebuilder with the new field coils and ask him to replace them. There is a clearance spec to the armature but I don't know what it is

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