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Old 01-04-2017, 10:42 PM   #1
DJ S
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Default Generator Rebuild

I'm rebuilding my generator and I purchased new field windings. I installed them but the armature doesn't have enough clearance... How do i resolve this? Also I don't know if my field windings are on the right side, how do i determine if there are or aren't?
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Old 01-04-2017, 11:29 PM   #2
Tom Wesenberg
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Default Re: Generator Rebuild

Here's a thread that should give all the answers.

http://www.fordbarn.com/forum/showth...+north+compass
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Old 01-05-2017, 06:12 AM   #3
DJ S
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Default Re: Generator Rebuild

Excellent write up! Thank you. However it still doesn't mention how to resolve my clearance issue.
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Old 01-05-2017, 06:48 AM   #4
RonC
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Default Re: Generator Rebuild

I had my new coils swapped out at a generator rebuilding shop. They need to be expanded and there is a pole clearance spec to the armature which I dont know. Harbor freight sells muffler expansion tools that look like they would work to compress your coils into the case for clearance. You may have to remove your screws and temporarily use bolts to pull the poles into the coils while expanding the muffler tool.
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Old 01-05-2017, 09:32 AM   #5
Tom Wesenberg
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Default Re: Generator Rebuild

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Excellent write up! Thank you. However it still doesn't mention how to resolve my clearance issue.
As Ron said, it takes special equipment, which I don't have. I bought an old pole shoe tool, but the bits are missing, and so far I've had no luck in locating some. I've had to have the local generator shop tighten them for me, but the last time they charged me $10 to tighten the two screws, so I'm going to try to make my own tooling.
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Old 01-05-2017, 04:16 PM   #6
Herb Concord Ca
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Default Re: Generator Rebuild

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First the new field coils need to be formed to the ID of the generator case and also to the pole pieces. Then to seat them in the generator I use C-clamps to form them into position and then install the pole screws.
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Old 01-05-2017, 05:41 PM   #7
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Default Re: Generator Rebuild

Well, I went to an Auto Electric Shop about half an hour away from me and I showed them what I needed done. They took the generator into the shop area and came back about a minute later, all done. They didn't even charge me. Thanks everyone for the information!
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Old 01-05-2017, 10:40 PM   #8
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Default Re: Generator Rebuild

Now that I've got everything back together, it doesn't motor... What could be the cause of this and what tests can I perform to check for a flaw in my work.
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Old 01-05-2017, 10:43 PM   #9
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Default Re: Generator Rebuild

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Now that I've got everything back together, it doesn't motor... What could be the cause of this and what tests can I perform to check for a flaw in my work.
You will still need to install it in the car and polarize it. Put it in, hook up the wires and take a jumper and just a quick touch across the cutout terminals. Should be good to go then.
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Old 01-05-2017, 11:45 PM   #10
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Default Re: Generator Rebuild

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Now that I've got everything back together, it doesn't motor... What could be the cause of this and what tests can I perform to check for a flaw in my work.
What is your power source?

A battery charger 6 amps or larger should make it motor.
Does the armature turn freely?
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Old 01-06-2017, 07:56 AM   #11
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Default Re: Generator Rebuild

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What is your power source?

A battery charger 6 amps or larger should make it motor.
Does the armature turn freely?
My power source is a 6 volt car battery.

I did make the observation that the armature wasn't turning freely. It seems to be binding on the brushes...
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Old 01-06-2017, 08:59 AM   #12
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Default Re: Generator Rebuild

I don't ever recall hearing of brushes binding on the commutator, but I use an ATLAS hobby saw from the Model Rail Road store to undercut the insulation between the commutator bars to about .010". After the undercut is done I spin the armature in my lathe while holding fine crocus cloth against the commutator. I spin it both directions, and this will remove any sharp edge from the bars, and in fact it will give the edge a slightly rounded surface for the brushes to enter each bar. A sharp edge could wear the new brushes very quickly.

Also notice the brushes have a slight angle where they contact the commutator. This angle gives each brush a short side, and a slightly longer side. The shorter side always faces the pivot post for that brush. Also note the thin brush is the adjustable brush.
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File Type: jpg Generator End Plate 30.jpg (75.0 KB, 81 views)
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Old 01-13-2017, 06:08 PM   #13
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Default Re: Generator Rebuild

So, I finally returned to my generator project after attempting to get it to motor. Once I took it apart, I instantly saw what was wrong. The amrature is scraping the poles, ever so slightly, but just enough to make it bind. I tried putting the armature in without the brush plate and there is more than enough clearance between the poles and the armature. As soon as I add the brush plate, it binds. Now my guess is the armature is bent. What does everyone think? Is there a way to check for straightness?
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Old 01-13-2017, 06:26 PM   #14
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Default Re: Generator Rebuild

I've never seen a bent armature. Did you replace the rear bushing, and if so is it too tight?
I almost never have to replace the rear bushing when I restore a generator.

How is the end play? There shouldn't be any washer at the rear of the shaft. The front bearing sets the armature position and controls the end play.
In the past I've posted pictures of the front shaft assembly, in case you need to see the parts.
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Old 01-13-2017, 06:39 PM   #15
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Default Re: Generator Rebuild

The bushing has been replaced and reamed. I entirely rebuilt and assembled the front shaft assembly using photos i had taken during disassembly and bratton's catalog.
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Old 01-13-2017, 06:55 PM   #16
Tom Wesenberg
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Default Re: Generator Rebuild

Is the end plate stamped steel, or is it cast iron? I have seen a bent steel end plate, and with a new busing it would bind because the bushing was no longer in perfect alignment. Check the end plate to be sure it's fully seated all the way around. Some end plates have a pin and slot for correct alignment, or it may have an upset and notch in the barrel for alignment, and it really messes things up when people start doing dumb things to the parts so they can mix and match parts not meant to fit each other.
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Old 01-13-2017, 07:01 PM   #17
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Default Re: Generator Rebuild

It's a cast iron end plate and it is on entirely all the way around. I'm absolutely stumped.
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Old 01-13-2017, 09:06 PM   #18
Tom Wesenberg
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Default Re: Generator Rebuild

Does one spot on the armature rub as it passes each pole shoe, or does one spot on the pole shoe rub all the way around on the armature?
The first would be a bad armature, and the second could be a pole shoe not tight enough to the case.

Here's the armature exploded view. Assemble the top picture from right to left, and the first lock ring must be tight to the shaft or it can scrape on the thin bearing retainer, which must not be bent, or it will scrape and make noise.
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File Type: jpg Generator Bearings 1929 Exploded View.jpg (48.9 KB, 61 views)
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Old 01-14-2017, 08:12 AM   #19
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Default Re: Generator Rebuild

The armature appears to be binding on a small patch on one of the pole shoes. Tbe pole screws were professionally tightened by someone with many years of previous experience with specifically Model A generators.
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Old 01-14-2017, 09:23 PM   #20
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Default Re: Generator Rebuild

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The armature appears to be binding on a small patch on one of the pole shoes. Tbe pole screws were professionally tightened by someone with many years of previous experience with specifically Model A generators.
Maybe Tom will chime back in on this
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