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I was rebuilding a 3 spring Victrola motor for a XVIII I am restoring and discovered a new process i wanted to share. I noticed the main drive spindle end where it contacts the bearing was cupped pretty bad so decided to put it on the grinder to make it flat again. I did the same with both ends of the governor, added new bearings to all of them and after reassemble found it to run smoother than before. With the flat ends and new bearings there is very little surface contact and makes for extra smooth operation. The grinding was with a fine grade stone and removed very little material, just enough to get the ends flat.
I didn't get a before and after but had another to show the difference. If you are rebuilding, try going that extra and see the difference,

Hey, Jon: I thought that dimple was for mating with a ball bearing that hides down where the spindle seats but maybe it is the result of wear after all!

Your intentions are good, and I don't mean to shoot you down. Yet, that dimple may not have been a problem. There is about 500 times more friction caused by the surface area of the two bushings the turntable shaft runs in, than that dimple would cause. In addition, unless you have precision faced that shaft so it is absolutely perpendicular to the centerline of the shaft, you may have created a new issue down the line. Most Victrola's I've dismantled have that same dimple.

A process that is known to reduce friction, is to polish the two bushing areas on the shaft in a buffer and clean the whole shaft well before re-assembly and then properly lubricate the two spots.

As mentioned above, unless the newly ground face is absolutely perpendicular to the shaft, you'll have done little good. Also, the ground surface appears to be fairly rough in your photo. This also can have ill effects. Nothing you've done is "wrong" or detrimental, it just has to be done with a good level of precision. I'd say the refacing of the governor shaft end, (only the one end that gets the thrust load), might yield the most benefit, but again, when done with precision. I've found this to be the case with disc music boxes, where the governor shaft should have a highly polished spherical end where it rides against the jewel.

This almost sounds like clockmaking here-- polishing pivots and all that.

startgroove wrote:Your intentions are good, and I don't mean to shoot you down. Yet, that dimple may not have been a problem. There is about 500 times more friction caused by the surface area of the two bushings the turntable shaft runs in, than that dimple would cause. In addition, unless you have precision faced that shaft so it is absolutely perpendicular to the centerline of the shaft, you may have created a new issue down the line. Most Victrola's I've dismantled have that same dimple.

A process that is known to reduce friction, is to polish the two bushing areas on the shaft in a buffer and clean the whole shaft well before re-assembly and then properly lubricate the two spots.

My grinder has a plate 90 degrees from the wheel so it is pretty straight, i wouldn't recomend it freehand. Like i mentioned above, very little material is removed, just enough to make it flat again. I didn't take a picture of it before grinding but the dimple was pretty substantial. I also did put it on the polishing wheel but didn't photograph it.
The dimple was not there when it was manufactured i assure you, the less contact with the bearing, the less friction. This motor runs smoother than any others, it could also be the model but it runs very quiet and well balanced.

Jonsheff wrote:I was rebuilding a 3 spring Victrola motor for a XVIII I am restoring and discovered a new process i wanted to share. I noticed the main drive spindle end where it contacts the bearing was cupped pretty bad so decided to put it on the grinder to make it flat again. I did the same with both ends of the governor, added new bearings to all of them and after reassemble found it to run smoother than before. With the flat ends and new bearings there is very little surface contact and makes for extra smooth operation. The grinding was with a fine grade stone and removed very little material, just enough to get the ends flat.
I didn't get a before and after but had another to show the difference. If you are rebuilding, try going that extra and see the difference,

20200527_193314.jpg

I am at a loss to see how the cupping could be attributed to wear: however, I have seen references to ball bearings at the bottom of spindle shafts, which were cupped to receive them...

I am rather loath to tear down my Victor motors to confirm this; but I suspect the problem you had was due to a missing ball bearing.

- Bill

Every spindle shaft I have seen has had a cupped end... this would make sense, as the wear would be distributed across a face, and not a specific point.

Garret

Garret wrote:Every spindle shaft I have seen has had a cupped end... this would make sense, as the wear would be distributed across a face, and not a specific point.

Garret

Hmm.. not all , picture is a 1925 HMV shaft , brand new as shipped from the factory for the UK MOD in protective wax , completely flat bottom , and doesn't that make sense the spindle is only touching the top of the ball bearing so only tiny point contact , if it were cupped you would probably increase the contact area 100 X ? thus producing more friction , perhaps the cupping is wear on the spindle shaft which may be the result of the ball bearing being harder than the shaft ?

Ball bearings are very hard , Volvo the car company was originally started as a company making ball bearings, the called the company Volvo , Latin I roll ! Volvo wheel bearings outlast the car unlike many which are lucky to do 50,000 miles

I've always believed the cup was indeed wear-caused. The spindle exerts a good amount of pressure against that ball, and every kick you give to the spindle or turntable goes to that hard ball...