And yet more generator issues

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Model T Ford Forum: Forum 2017: And yet more generator issues
Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Wednesday, July 19, 2017 - 05:40 pm:

New field windings and checked for NSNS
New bushes, lapped to fit
Armature checked and re checked on growler does have a lite burnt smell but can't find any shorts
No shorts to ground brush holders
New bearings
New terminal post and lead
Wires crossed
Polarized but even then only an occasional spark at the terminal. Good battery.

3rd brush up or down NO motor!
Even tried to un cross the wires but still no luck.
Using a KRW test stand I did get it to gen once, but it was a run away! over 20 amps output. Let the smoke out of the cutout.
I rechecked everything after that and still no motor. I have had it apart too many times now and am not about to give up. The commutator isn't grounding out on the brush plate nor are the shoes to armature.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stephen, South Texas on Wednesday, July 19, 2017 - 08:09 pm:

I only have about 18 years of rebuilding and customizing generators and according to Andre Valkenaers, that's not enough to answer questions. But to get the ball rolling on this thread, I'll just ask a couple of questions.

What, if anything, did you do to the Commutator?
Did you replace any parts on the brush plate?
Are you saying NONE of the brush holders are grounded? (To clarify-Should be one.)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Wednesday, July 19, 2017 - 08:37 pm:

Really, Stephen? You had to start your answer that way?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ted Dumas on Wednesday, July 19, 2017 - 08:51 pm:

Following up on Stephen's comment, you might run a thin hacksaw blade down each commutator slot and make sure none of the commutator bars are shorted to adjacent ones.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson-Nicholasville, Kentucky on Wednesday, July 19, 2017 - 08:52 pm:

I too wondered how the commutator was finished, but more importantly how was the brush plate null point set? I think this one is easy, but perhaps "I only fix what's wrong" Sims or "push button generator build up" Brian will enlighten us all with their sage wisdom and guidance?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson-Nicholasville, Kentucky on Wednesday, July 19, 2017 - 08:57 pm:

Ted
I was not present, but M ark claims the armature passed the growler test.
A poorly finished commutator will work, but won't last.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson-Nicholasville, Kentucky on Wednesday, July 19, 2017 - 09:03 pm:

Properly finishing the commutator is the single most important factor in the long term reliability of a rebuilt Model T generator.
The devil is in the details!!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Brian Billing on Wednesday, July 19, 2017 - 09:22 pm:

I'm sorry Ron, but I'm having trouble comprehending '"push button generator build up" Brian will enlighten us all with their sage wisdom and guidance?

I assume you're referring to me? I have conducted the tests you advised and reported back on my thread, and would be really appreciative of your guidance in helping me diagnose and hopefully rectify the problem I'm having. If I have somehow upset you, please, accept my apologies, I certainly do not wish to offend anyone, particularly an expert in their field [no pun intended], respectfully, Brian


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Wednesday, July 19, 2017 - 09:25 pm:

I just did a clean up cut on the commutator, someone in the past had really gone deep between the segments. I will go back and take another look, I did some cleaning but maybe I missed some smuts. Yes I meant the holders that should not be grounded were not the one that is, is.
I cant get the gen to motor set the null point.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Blancard, Fredericksburg Va on Wednesday, July 19, 2017 - 09:30 pm:

Not to get sidetracked, but this is a much better tool for undercutting mica than a hacksaw blade. It allows for precise width and depth of cut. They aren't easy to find anymore, but are a great addition to any shop. cutr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson-Nicholasville, Kentucky on Wednesday, July 19, 2017 - 09:32 pm:

Brian
Please forgive me. Brad, not Brian.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson-Nicholasville, Kentucky on Wednesday, July 19, 2017 - 09:52 pm:

Steve
Your exactly right.
Any competent Model T generator rebuilder has one of those or a functional equivalent.
But, Mark claimed to have checked the intrer segment undercutting and the armature did not "growl".
If the commutator isitface is properly finished and the brushes properlyy seated, proper inter segment under cutting will not prevent the generator from charging, but it will severely affect long term reliability of the generator.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson-Nicholasville, Kentucky on Wednesday, July 19, 2017 - 09:52 pm:

Steve
Your exactly right.
Any competent Model T generator rebuilder has one of those or a functional equivalent.
But, Mark claimed to have checked the intrer segment undercutting and the armature did not "growl".
If the commutator surface is properly finished and the brushes properlyy seated, proper inter segment under cutting will not prevent the generator from charging, but it will severely affect long term reliability of the generator.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson-Nicholasville, Kentucky on Thursday, July 20, 2017 - 08:03 am:

Mark
I thought more about your problem and I think there is a problem with your armature. I understood you to say with the third brush off the commutator, power applied and moving the brushplate backward and forward the armature would not rotate. There must be a problem with your armature. You tested it with a growler, but did check to see if the commutator is not shorted to the armature shaft? If so try another armature.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Thursday, July 20, 2017 - 09:42 am:

Ron;
I ran the 120V probes around the core and shaft to check for shorts, none found. I am going to take a closer look at the area between the commutator segments to see if I over looked anything. That failing, I am going to try a different armature.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson-Nicholasville, Kentucky on Thursday, July 20, 2017 - 10:15 am:

Mark
Check between the armature shaft and any (they are all wired in series) commutator segment with an ohmmeter. I am always suspicious of the 120 volt probes because the lamp has commonly been replace with a higher wattage bulb.
Clean each commutator slot with the pointy end of a large safety pin and then polish the commutator surface preferably on a lathe with a narrow strip of #600 sandpaper till it is smooth as a baby's fanny and almost like a mirror. Blow out each commutator slot with compressed air.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Thursday, July 20, 2017 - 10:45 am:

OK will do. I did rotate the brush plate when trying to get it to motor.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stephen, South Texas on Thursday, July 20, 2017 - 11:31 am:

As an addendum, check the vertical area of the commutator slots as well as the winding's soldered terminus area. Be sure there no commutator segment bridging in those areas too.

Does your growler have an ammeter and a probe with two small pins about 1/4 to 3/8" apart?

If so, this can be used to check for adjacent commutator segment shorts or intra-winding shorts. These conditions may not show up in the standard growler test.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Thursday, July 20, 2017 - 06:47 pm:

First I checked each segment of the commutator to shaft, no shorts. Then I checked connectivity of each segment to the adjacent segment, no connection, dead except in one spot. Then I checked the other armature, same test but each segment was connected to the one on both sides. Now if I read what Ron wrote, it is wound in series so that should be good.
I assembled the generator, motors now, set null point. Put on test stand and set output to 8 amps. After running for about an hour (motor is direct drive so RPM is higher then what average car motor speed would be)it did get on the hot side. Once on the car we will reset the output.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stephen, South Texas on Thursday, July 20, 2017 - 07:56 pm:


quote:

"I checked connectivity of each segment to the adjacent segment, no connection, dead except in one spot."




That armature is dead. ALL segments are connected by coils in a series wave winding. You should see continuity from segment to segment and to any segment around the commutator. Each segment has connections for two coils--The start of one coil and the end of a different coil.

Ron made a nice graphic to show the series wave for a few coils. I hope he doesn't mind me posting an excerpt. (See below)

Glad you found an armature that works.



Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Thursday, July 20, 2017 - 10:25 pm:

OK here is one for you; I have two more armatures, one passes the growler test but every commutator segment is shorted to the core/shaft the other fails the growler but can't find any shorts between the commutator segments and core. Have fun with that. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson-Nicholasville, Kentucky on Thursday, July 20, 2017 - 10:42 pm:

Mark
A good quality "Growler" test apparatus will allow three comprehensive tests.
1. Commutator shorts to ground (shaft/laminations). The 120 volt probe test through a low wattage bulb. This test is a bit dangerous and bettered left done with an ohmmeter
2. Growler tests for ALL inter and intra winding shorts. i.e. The hacksaw blade test on the transformer laminates to induce currents in closed circuits. Normally in a good armature all circuits are open circuit
3. Individual armature winding test. Each adjacent commutator bar is connected to one armature winding. The growler is activated. A set of probes are connected to adjacent bars with an ammeter in series to detect current flow. Stephan discussed this test earlier.
Your original armature would have failed #3 above.
Isn't Model T generator trouble shooting fun??
P.S. The simplified armature winding diagram above was prepared by a fellow in Texas and I confess in my advancing age his name escapes me.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Thursday, July 20, 2017 - 11:09 pm:

:-)


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