Remove Field Coils From Generator

johnr9q@yahoo.com

johnr9q@yahoo.com

Senior Member
The two screws that hold the field coils in are tight. I let them soak in penetrating oil all night and tried using an impact screwdriver. Any suggestions?
 
I made this fixture and bought the Harbor Freight screwdriver set,and just got an exhaust pipe expander set to push the field pieces tight.
way back I used a hammer and impact screwdriver and a lot of beating and screw buggering.

If you want more pictures I will be taking a T generator apart later today
 

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FB user ndnchf has a video somewhere showing his setup, I believe he uses a drill press with a V-shaped jig to hold the generator. The press keeps the bit from camming out, then he turns the bit with a wrench.
 
If you are replacing the field coils anyway, just heat the bolt heads with an acetylene torch until red. Let them cool and you will be easily able to back them out with a big, wide blade screwdriver. The heat from the torch will ruin what wrapping material is left on the field coils, so plan on replacing them, which I assume is why you want to remove the coils in the first place? If, on the other hand, you intend on re-wrapping the coils yourself, ruining the old wrappings with heat is no big deal. Most unrestored field coils need to be replaced or re-wrapped anyway. You will have lost nothing by heating the bolts and making the old wrappings un-reusable.
Marshall
 
Take two large C clamps and clamp the iron poles to the case. That takes the strain off the screws and makes them easy to take out.
 
I also have this screw jack that works very well.
 

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I friend of mine uses his large drill press to do essentially what Steve does with his Arbor press. Always works for him.
 
The hole in the top bar is just large enough for the extension to fit through,should drill another hole for 3/8 extension.
The length on mine was determined by pre existing holes.
The threaded rods should rub some on the top bar so when you are setting it up the bar stays out of the way until you move it.
Wack the extension to seat the screwdriver bit .
If you custom grind one of the screwdriver bits for exact full length and thickness and cut the corners for the taper no marks will be made on the screw slot.
I use a copper hammer on the extension and if the screws don’t come out easily they get whacked again—- in other words— don’t force it and break the screwdriver bit.
 

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More ways than one to skin a cat. All suggestions made so far will do the job. It depends upon available equipment, how destructive the OP wants to be, and to some degree - luck. Sometimes those bolts cannot be turned out without resorting to drastic measures.
One additional method not suggested is to take a long chisel and drive it down between the generator case and the field coils. This method will shear off the bolts, but it also twists the field coils and shreds the wrapping material. The bolt shanks will then need to be drilled out of the pole shoes and the holes re-threaded - if the old field coils are to be re-used. Of course, that means nothing if the OP plans on simply installing new field coils with two new anchor bolts.
Marshall
 
For me, it's much easier to just drill the countersunk head off. When I install the field coils, I use big C-clamps to hold the pole pieces tight against to case and then tighten the screws.
 
On average I probably remove/install 2, maybe 3 sets of field coils every week. I seen all knids of sscrews used and encountered just about every type of difficulty there is. About 90% come out with a screw jack. The others strip the screw slot or round the recessed Robertson head. The easiest way to handle these is to simply drill these out on the drill press. I would never heat a screw red hot. Some of that will transmit to the body likely causing distortion or warping. The generator body is precision machined internally to an exact diameter. With the shoes and fields installed there is only about .010" - .012" clearance between the armature and pole shoes. Any distortion of the body could cause the armature to bind between the pole shoes. Trying to shear the bolt with a chisel between the pole shoe and body would only result in destroying the pole shoe. Don't even try it. Just drill out the screw.

If you need help with it, feel free to reach out to me.

Steve
 

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There is a small gap between the housing and the steel poles. Squeezing the pole to the housing will take a lot of stress off the screw. Take two large C-clamps and squeeze one pole at a time against the housing. This reduces the torque required to remove the screw. You may not need to drill it out or use one of the techniques to force the screwdriver to stay in the slot. I use an impact screwdriver and it easily removes the screws after clamping the poles with the C-clamps. I use the same technique for re installing the poles.
 
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