DC motor problems

Michael A. Terrell Inscribed thus:


A very profitable exercise nowadays with the price of copper being so high. I just wish the thieves would stop stealing the iron grates and aluminum road signs. A whole load of them have vanished overnight. Not to mention the theft of copper wiring from the railway system.
Next door neighbor came round today and asked if I knew that water from the kitchen sink was pouring out of the wall and onto the yard !!! The swine had pinched the two meters of lead drain pipe between the wall and grate,
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Best Regards:
Baron.
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Baron wrote:

They are destroying central air condition equipment around here, for the couple dollars worth of copper tubing. Some businesses were hit twice within weeks. Their insurance only covered it once. Some of the thefts were from non profits that had no coverage and had to do without it in Central Florida. :(
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On Wed, 07 Mar 2012 05:33:57 -0500, "Michael A. Terrell"

The problem is pretty easy to solve, given that the legislators *want* to solve it. That they haven't tells us a lot.
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" snipped-for-privacy@att.bizzzzzzzzzzzz" wrote:

Yeah, like all of a sudden Obama gives a shit about our military losing their homes while serving overseas, but it wasn't important before time to run for re-election.
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On Wed, 07 Mar 2012 11:30:00 -0500, "Michael A. Terrell"

Obama is like AlwaysWrong. If you want to know what he wants to do, just reverse what he says. He will always do the opposite of what he says he wants.
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" snipped-for-privacy@att.bizzzzzzzzzzzz" wrote:

Homerland Security stated:
"the return of military veterans facing significant challenges reintegrating into their communities could lead to the potential emergence of terrorist groups or lone wolf extremists capable of carrying out violent attacks"
Now the same party is doing a 180 turn?
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On Thu, 08 Mar 2012 08:28:12 -0500, "Michael A. Terrell"

Sure, they figured out that it didn't "poll" well in their focus groups.
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On Fri, 02 Mar 2012 21:48:04 -0500, Oppie wrote:

You need high speed (~200 ft/min) and a *very* sharp tool. Commutators are a bitch to machine to a decent finish without ripping the segments off..
Cheap commutators sometimes have very thin segments, maybe .025" thick.
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over public relations, for nature cannot be fooled."
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When in doubt I use as close to a zero rake as possible to avoid pulling out the copper bars. Most of the motors I've worked on are pretty old and they didn't skimp on the thickness of the copper. I would use a pointed cutting tool and a really slow feed rate to get minimum cutting forces. Last pass would be with a more rounded tool just to smooth it out and finally the fine grit to polish it out.
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Use a battery and momentarily connect the field winding. This "magnetizes" the armature (do this with the motor un powered). You only have to do this once.
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Any chance that the angle between the brushes and the field got changed on reassembly?
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John Larkin, President Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
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Actually, yes. The rear casing of the motor that contains the brush holder can be mounted to the main motor frame (containing the field) at 90 degree increments. So 4 possibilities.
I reassembled the motor as I thought it was originally configured but the possibility that it's incorrect is large.
I'll try other orientations tomorrow.
Thanks John!
Dave
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Is there only one correct orientation? Or 2?
Thanks, Dave
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DaveC wrote:

Two--one for each direction! :-) Whenever I disassemble a motor, I scratch a mark across the "parting line(s)". Then I know how to re-assemble it.
--
Virg Wall

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VWWall wrote:

The idea is good, but there's a better way. Use a punch and put matching dimples across the 'parting lines'. Put one set on one end and two sets on the other.
mike
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He now knows the importance of some sort of a mark
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Some 'brush sets' are 180 degrees apart, and that right on the center axis of the brush 'monolith'. Some are oriented slightly off center (but still 180 degrees apart). Usually on a motor only meant to spin in one direction. The result is that the brush face has the arch <sic> abraded across it slightly off center,and may only have one 'correct' re-installation orientation that will preclude chipping and unneeded wear-in sessions.
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The two brushes are mounted exactly 180 degrees apart. But the brush holder is adjustable (in rotation). I haven't touched that adjustment, so if I just get the gross orientation correct (90 degrees from current setting) all should be well.
Thanks, Dave
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DaveC wrote:

Wave you measured the current in each circuit? Are the field windings wired properly? If you reverse one it's not going to run.
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No current measurements made.
I tried reversing all connections. No joy.
Thanks.
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