I had a 5513 Sub come in a while back for a full service. The Cal. 1520 was in decent shape, but one issue was the oscillating weight was cracked - have seen this on a couple of occasions in the same place:



As you can see, someone has tried repairing it with soft solder, and that didn't hold:



Disassembled:



Working on the base movement, wearing myTudor Sub:



Since there wasn't any significant distortion, I sent it to a buddy of mine to have the soft solder cleaned off, and then they laser welded it - looked quite good after the repair, and hopefully this will hold:



The crystal was not bad, but could use some work:



In progress:



Close to being done - just a few minor scratches left (actually something on the cloth I used to wipe it off, so these were easily cleaned up):



All done and looking quite good:



Cheers, Al

 

Looks good now Al.

I've seen a few wiffle balls break like that too.

 

Great work Al,
Just curious, how come a rotating parts could get cracked? Metal fatigue? Sudden shock?

Regards,
Herianto

 

I'm guessing it received a shock at some time (likely multiple shocks over time causing work hardening in that area), causing the weight to delfect enough to crack there. As I mentioned I've seen this before. This is a 1680 Red Sub I did a few years ago and it had the same break in the same spot - for this one was the weight was replaced though.



Cheers, Al

 

Thanks Al. Probably multiple vertical shock. I am still amazed this could happened in strengthened stainless steel.

 

I had one recently that I was checking for a mate before it went off to a watchmaker.
Rotor was cracked in the same area. If you look at the design you can see that the outer radial slots have sharp corners. A great way to focus stress in one area. I'll see if I can find a pic.

 

Yes, sharp corner in metal sheet invites crack quickly in vibrating environment.

 

This area of the weight is plated brass. If you look at my second photo above showing the underside of the weight, you can see where the last repair was done using solder, and the rhodium plating was removed to help make it stick - brass showing in some areas. These aren't steel - the vast majority of a watch movement is made of brass that is plated. There are some movements made of other materials ("German silver" being another one), but brass is by far the most common.

Cheers, Al