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I have a Victor 4-spring motor from a Credenza I've been rebuilding. After getting everything assembled, I noticed there's a persistent chatter and oscillating grinding noise that wasn't there before.

What seems to happen, is the spindle shaft worm that meshes with the large drive gear on the spring barrel, is binding and scraping on some burrs. I must've accidentally created them while cleaning out the gear teeth (perhaps a bit too aggressively for a metal as soft as brass ) My current theory is the "chatter" comes from a repetitive build-up of pressure in the spindle mesh suddenly being released as the shaft turns. I've found that this pressure is only released once the governor worm has "pushed" the spindle enough through the smaller drive gear.

Regarding the removal of burrs on brass gears, which methods have you had the best results with? I've heard of filing and lapping burrs smooth, however I worry about causing further damage to the gear by filing something in the wrong way. Any advice would be greatly appreciated.

Can you post a picture of the burrs?

Typically, a small, fine file is best. However, you need to be extremely careful to only file away the burr! Several times I have advised filing away a small burr only to have the person get carried away and file away the undamaged portion of the gear tooth as well... ruining it.

The only brass gear in that motor should be the one that drives the governor.

Any updates?

JerryVan wrote: Thu Aug 15, 2024 10:05 amAny updates?

It turns out I had lubricated the motor wrong (not enough grease, using grease where I should've used oil, etc.) Rookie mistake.
I took it to a local repair shop, and was shown how to properly lubricate the gears, and bearings. The motor is running much smoother now without any loud grinding or loss in speed. A little noise is still there, but that's simply due to a century of wear carving little "scoops" into the teeth.
In my opinion, Victor probably should've used a beefier gear, considering the amount of force it deals with, but I doubt those motors were designed with 100+ years of use/abuse in mind.

That being said, I did use a jeweler's file to carefully knock down a few of the burrs, but in the end, I think the issue was 90% lubrication.

Interesting... Maybe the narrow bull gear, if made thicker, could have caused too much drag on the spindle worm. The change from standard gears to bull gear and worm was a great improvement regarding the silent work of the motor. Older motors with standard gears are much more noisy.

However, as Jerry already anticipated, these gears were machined with very high precision / low tolerance; much lower than one would expect given the simplicity of the mechanism.

On occasion, I tried to file the teeth of gears that came damaged by one accident or another, and I've never been able to get a motor running acceptably again.

I agree with Marco's observation about the tolerances of gear meshing. Having rebuilt a number of turret clock movements with some wheels (gears) 18" in diameter that mesh with 3" wheels, I've learned that properly cut gears have tooth faces that do not slide, but "roll"on to and off of each other and only need to be cleaned, not lubricated. Only worm gears and bias-cut gears require lubrication. I once hand polished two damaged teeth on a big gear only to create a new wear pattern on both gears! I learned the hard way. R.