A noise annoys this oyster

[randgust]

OK, so for years we've had the same posts and repeated issues with the Kato/Atlas GP series creating noise where Ron Beardon's bearing block removal has been a fix, although a rather awkward one.   It all revolves around those hex-nut universals banging around in the flywheels creating noise, right?  And Atlas finally fixed it with a new design, but there's a TON of old ones still out there.

I've got a Kato-Atlas GP35 that had more racket than anything else I own, it had been demoted to display case.   Dug it out and looked at it again, well, your time has finally come.   I'm beating this thing once and for all.  The odd thing is that I've got another one that is just perfect, silent, and pulls like a champ.   This particular one has been a POS since I got it.

It was rather obvious in testing that the noise was primarily from the rear, and only when running in forward so it didn't take long to do the Block Treatment, reassemble, and test.  Done.  Surprise, it's just as bad as before.   Hmmmm.

Played around with washers, shims, tolerances, probed with tweezers under power, tried with and without shell,   Man, this thing is noisy.   Intolerable.

As I'm an old IT guy, you learn to eliminate variables to find solutions, in this case tear EVERYTHING out but the motor in the cradle, put it in the shell, and start working out one component at a time.

Well.... even with no trucks, no gears, nothing but motor and flywheel in the frame....Bzzzzzzz......   Seriously?

Flywheel rubbing frame?    Played with tweezers under power and pushed motor while spinning, and it only made racket when pushed to one end under load.    OK, grind out some frame.   Fail.  Still noisy.

OK $#! well take the MOTOR out, and just check that under test power.    Holy crap, it's the motor.   When it's pushing to one end, it's hitting something inside the motor where I can't see it and vibrating like crazy.   This is a Kato motor, that doesn't happen, right?   Well, kiddies, it's the motor.

I had one leftover 448100 Atlas slow-speed motor replacement, smaller flywheels, slightly shorter, but fit in the cradle.   Hmmm.   Worth a shot, reassembled it all all the way through the worms and universals (which were more sloppy than the original)....put the shell on.....

Silent.   SOB!!!   All these years this thing has been laid up bad order and it was actually the motor, not the universals.    Reassembled the whole thing and tested it with a new Atlas GP38 and runs nicely with it (and is a LOT heavier).    But I had to tear it down to individual pieces to find it, and finding it was one of the more satisfying exercises lately.

My local railroad, the Allegheny, had a very attractive dark blue and orange scheme until it was Borged by G&W and turned everything orange, and now every unit they have is gone or scrapped - 2 CF7's, 2 GP40's, 2 GP35's.   One lone survivor is GP35 #305, which hung around for a long time but is now a stripped road slug #102 and painted orange.   This will be my tribute unit, now that it's worth salvaging.  305 it is.

And I may tear apart that Kato motor, that's the kind of thing I do.  It's driven me nuts for enough years it deserves torture at this point if I have to unwind the windings to find whatever gremlin was in there.

And, I've got two more Atlas "classic" GP chassis that were also demoted due to noise, so this should be fun.   I'm doing the same thing there, but I think the Beardon Block treatment will actually work there.   Or so he said.

[CRL]

Quick... someone call MPS (Motor Protection Service)!!! There’s an assault in progress!   

But seriously... congratulations on your investigative success. Shows the rest of us to start with the first link in the chain when troubleshooting an issue.

[randgust]

You know the "Toy Story" movie "Sid" character villain that tore apart his toys and crossed them to make all manner of oddball creations?

Yeah, that's me.  Drove my parents nuts because I tore everything apart to see how it worked.   Sometimes I got it back together, sometimes not.  Worst fail was when I tried to 'fix' the carburetor on my snowmobile.   It never ran again.  Ever.  Sold it for scrap.  And the guy that bought it never got it to run either.   And that gene was inherited by one son that made an electric motorcycle out of what had been a normal Huffy bike, it now has enough electrical torque in it to do wheelies.   Powered by enough reclaimed laptop batteries (200 cells, 2.2kwh)to work as a short-term arc welder.  Equipped with temperature monitoring and a heat shield.

Toys fear me still.

[u18b]

Sometimes it can indeed be a motor with a slightly bent shaft (or I guess a flywheel out of balance).

I cannot remember that happening with a Kato motor, but I've seen about 2 Atlas motors.  Bob Horn had a B40-8 that drove him crazy.  When I visited his house, we experimented and traced the problem to the motor.

And just for the record.... the Beardenizing removal of the inner bearing block only solves one thing (when done properly:   http://u18b.com/wp-content/uploads/2019/10/Bearingblock09.pdf ).  It solves the slight drive train misalignment that causes noise.

But if there are other problems (like a bad motors) it cannot solve those.

And those are usually discovered by me exactly the way Randgust did:  Do the Beardenizing properly, and still not quiet.  OK, the problem must be elsewhere...

[peteski]

It is probably out-of-balance armature, or a bent motor shaft. 

Unless you have armature balancer, taking the motor apart will probably not be very useful. Unwinding the wire on the armature will liely make it more unbalanced. 

[randgust]

Remember my theme, I never claimed to actually fix it, I just want to find out WHY, and if I destroy it in the process, I'm OK with that.   At this point it's a scrap motor anyway.   Manufacturing defect?  Something melt?  Break loose?

I think there's something in the commutator area that is banging into the front frame of the motor on the commutator end, because it only does it when you shift the armature to one side when it is running.   To prove that, I have to pull the commutator end flywheel and tear the frame apart.   Likely will bend the motor shaft although I have a puller.   It 'just might' prove to be fixable, but either way, I learn something.   I'm mystified. it literally 'bounces' against the frame of the motor, making a grinding noise, and nothing is externally visible as to why.

I used to regularly pull apart Rivarossi, Trix, and Mehano motors, even managed to repair a few.      Remember the old Lindberg kits where you had a make a motor out of plates and hand wind them with wire and keep count?  Yeah, I did those when I was 12, some even worked.  And I still have a razor blade jig I made to balance armatures.
http://www.internetmodeler.com/2008/february/columns/how_motor.jpg

[Mark5]

Nice work, detective. 

[randgust]

Pulled the motor apart last night with my gear puller and pliers.   In the process, a brush spring flew into the nanosphere, might find it, but doubt it.

BUT, I found the problem, somewhat in a destructive way.  There was a tiny piece of flash/plastic/debris on the armature side of the commutator insulator.  Just big enough to hit the brush holder, but only when it was thrust to one side.  So, when the thrust was in one direction, it was literally 'bouncing' the armature off that debris/defect making that racket.   Trimmed it off, reassembled, did hand spinning and I don't feel it anymore.    I may or may not bother to replace the brush spring, I'm happier with the Atlas motor anyway, but to explain 'what tha $#!!' was in there, that apparently was it.   I've got plenty of salvaged motors, I think this is still salvageable, just currently unneeded.

Now, I'm going to take on the two other Atlas Classics that I have that I sidelined for noise, we'll see how I do on that.

[CRL]

Plastic flash remnants is a very common problem for any type of operation problem, and is the first thing I look for when troubleshooting. Even very, very tiny flash should be trimmed away, even if there’s “no way” it could be the problem. But this is the first I’ve heard of an internal issue with a motor being caused by this.

Good job finding the source.

[wm3798]

I'm reminded of an old Dennis the Menace panel...  "But Mr. Wilson, I had to break it to find out why it wasn't falling apart!"
How new engineers are born...
Lee

[peteski]

Randy,
I'm also one of the insatiably curious people who takes a brad new $1200 brass loco apart to see how it is made.  Same with everything else around me.  I have always been like that.  There are few of us here on TRW.  I admit that i had few instances that I have managed to break or damage whatever I took apart, but it was all done in the name of advancing my knowledge.

As far as the vibrating motor goes, I'm surprised that you expect to bend the motor shaft when pulling the flywheels off.  I have removed many, and never bent a shaft.  Actually as I see it, reinstalling a flywheel presents a greater risk of bending the motor shaft.

Next, I always remove brush holders (and brushes/springs) before taking the motor apart.   

Good detective work - too bad you don't have any photos - I would have been interesting to see the actual defect.

[signalmaintainer]

Pulled the motor apart last night with my gear puller and pliers.   In the process, a brush spring flew into the nanosphere, might find it, but doubt it.

BUT, I found the problem, somewhat in a destructive way.  There was a tiny piece of flash/plastic/debris on the armature side of the commutator insulator.  Just big enough to hit the brush holder, but only when it was thrust to one side.  So, when the thrust was in one direction, it was literally 'bouncing' the armature off that debris/defect making that racket.   Trimmed it off, reassembled, did hand spinning and I don't feel it anymore.    I may or may not bother to replace the brush spring, I'm happier with the Atlas motor anyway, but to explain 'what tha $#!!' was in there, that apparently was it.   I've got plenty of salvaged motors, I think this is still salvageable, just currently unneeded.

Now, I'm going to take on the two other Atlas Classics that I have that I sidelined for noise, we'll see how I do on that.

Nice find, randgust!