Music box movement

I am repairing a 1949 German cookoo clock that I have had for about 30 years. One problem is in the music box movement that plays a tune on the hour. For the last few years it has jammed up sporadically and would not play especially if the weight was near maximum. Occasionally pulling on the weight, not raising it to full height, or jiggling it slightly would loosen the mechanism and it would work for a while. Now it has stopped completely.

I have dismantled the clock completely for that and other reasons and have removed the music box movement. I have found the problem.

Music box movement.

Shaft is out of position, shifted to the right and gears bind. End of shaft protrudes on right.

Shaft is in correct position, centered on gear and they mesh properly. A worn area appears between the gear and the shaft support.

This looks very difficult to replace. Are such parts available? The bearing points are both part of the same metal piece and there is no way to remove/insert shaft without bending.

 

Some clock movements have been made for decades. If you can identify the maker/brand of yours that would be a big help to look online for parts. I think you are looking for the governor shaft or you might be able to replace the whole governor assembly. Even if you can't find an exact replacement you might get lucky and be able to use a new governor as a parts donor.

 

Could the worn place you speak about be a place for a c clip to be in order to stop the shaft from slipping too far to the right?

 

Yes, if the shaft diameter size was known maybe a side press-on C-clip might work to keep it positioned properly.

 

I looked around on line for repair/replacement sources and could not find an exact match. Also I was not sure of some of the terminology in the descriptions dealing with the number of pinion teeth. Also new replacement parts use plastic gear wheels. Here is the solution I came up with. I'm not sure if they would be called "C" clips, washers or spacers.



A thin piece of semi-flexible plastic with a 1/32" hole drilled and then punched out with a 3/16" hole punch.

Sorry about the focus. The spacer is then cut from the hole to the edge and twisted slightly to allow snap mounting it onto the shaft.

It took two of them to move the shaft enough distance to center it on the meshing gear. Looks gnarly but works fine.

This hole punch is smaller than a standard 1/4 inch punch but has come in very handy for non-paper projects. I recently used it to make contact pads from aluminum foil to restore a non-working TV remote whose carbon pad contacts could not be restored with conductive ink.

Thanks for all your suggestions.

 

I'm wondering it maybe the craggy edge of the homemade spacer you punched out might have a tendency to catch on the edge of that (what appears to be a turned-up metal shaft support tab) that could lockup the mechanism.

I think you are definitely on the right track! Can you find a smaller diameter metal washer with the hole diameter just large enough for the shaft? I looks like stacking two or three of them side-by-side may be ideal spacing width to center-up the gear where it needs to be for meshing.

 

Left-to-right: gear--spacer #1--spacer #2--support/bearing post. The spacer is "flat" against the gear wheel and the gear wheel is larger so the teeth are beyond the outer edge of the spacer Also the support post is wider than the spacer. Nothing to get caught on and in any case the shaft is spinning within the spacers. The spacers are not turning.

 

I just wasn't sure about this part (circled in red) you made remaining in position and not getting caught up somehow.



Sounds like you got it fixed!

 

Sometimes sequins will work. Use a sharp pair of dykes to cut a slit.
I have bins with them here as I used to repair tape decks and vcr's.

You can get a cool assortment here.... surplus parts

 

That's a good idea! And, a slit in it so you can slide it onto the shaft from the side. Stack them if necessary.


Or, if you don't mind removing the shaft from the support tab, a small nylon spacer could be used.

 

Good suggestions: sequins and washers. I probably have some of each around but did not think of them so I just built my own and they are working well.