Worn Arbor On AS 1423 Movement

[everydaycats]

I was bored and grabbed and old Elgin 643 out of my junk box to work on. Before disassembly It appeared the ratchet wheel was turning as it should when wound but watch never ticked. After taking off barrel bridge I noticed the arbor was completely flush with the bridge and ratchet wheel. was not engaged so simply spun on top of bridge. I don't think I have ever seen this. Ratchet wheel has no wear marks, so how does this happen? It is hard to really see how flush the arbor is with the bridge in this pic, but not a mm is above bridge.

 

[Dave Haynes]

The plate could be slightly bent from being prised when a screw was still in place. Sometimes the screw holding a click is also holding down the barrel bridge. Or it could be an incorrect arbor from another caliber.

 

[roughbarked]

Did a search on Ranfft for AS 1423. There are a number of calibres in the family. 1423 has a height 5.75mm, I didn't see any thinner ones in the list.
the 1424 has additional power reserve centre hand but the height is still the same.
Have you tested the endshake of the barrel arbor?

 

[everydaycats]

Did a search on Ranfft for AS 1423. There are a number of calibres in the family. 1423 has a height 5.75mm, I didn't see any thinner ones in the list.
the 1424 has additional power reserve centre hand but the height is still the same.
Have you tested the endshake of the barrel arbor?

End shake is what I consider ok or close to tolerance. There was movement, but not much. I initially thought the barrel bridge was bent from prying up by previous services, but when laying upside down on a flat surface it is perfectly flat. If I screwed it down enough to enngage the arbor then the bridge drags on the barrel. I went though all the simple tasks trying to figure it out. It may in fact be the wrong arbor or the entire barrel/arbor/mainspring may be wrong for the movement. I'm digging through my junk looking for a match so maybe that will tell the tail. However, it appears from close inspection that the top of the arbor is worn off. Hopefully I'll have it figured out soon and I'll post back here for other in the future.
Regards

 

[MrRoundel]

Is it possible that a past repair person didn't want to wait for the ratchet wheel to fit over the arbor well, and just tightened the screw and prayed? After a while the arbor might look like that. I was close to doing this on an ETA 2512 not long ago because there truly was very little arbor for the ratchet wheel to drop onto. I might have done it but the click spring wouldn't stay in place. With mine, it turns out the click-spring had distorted, which made it difficult to drop the ratchet wheel and engage the click. But that movement had a rather odd click/spring setup. Good luck.

 

[roughbarked]

Ratchet wheel has no wear marks, so how does this happen?

 

[everydaycats]

Is it possible that a past repair person didn't want to wait for the ratchet wheel to fit over the arbor well, and just tightened the screw and prayed? After a while the arbor might look like that. I was close to doing this on an ETA 2512 not long ago because there truly was very little arbor for the ratchet wheel to drop onto. I might have done it but the click spring wouldn't stay in place. With mine, it turns out the click-spring had distorted, which made it difficult to drop the ratchet wheel and engage the click. But that movement had a rather odd click/spring setup. Good luck.

...and, I suspect your description of previous service person tightening a screw on a worn arbor is correct. Which, in time wore the top of the arbor flush with the bridge. I did not try tightening the screw enough to check the click, but I believe the click would not engage enough to work properly. The previous service person may have had enough arbor to make it work, but that was/is not the proper way to service a watch. Anyway, it is interesting to see this, and I will know if that is in fact the problem when I find a replacement arbor in my junk. On many occasions I have seen the arbor pin that engages the mainspring worn off so arbor spins, but never a top completely worn off.
Regards

 

[everydaycats]

I was bored and grabbed and old Elgin 643 out of my junk box to work on. Before disassembly It appeared the ratchet wheel was turning as it should when wound but watch never ticked. After taking off barrel bridge I noticed the arbor was completely flush with the bridge and ratchet wheel. was not engaged so simply spun on top of bridge. I don't think I have ever seen this. Ratchet wheel has no wear marks, so how does this happen? It is hard to really see how flush the arbor is with the bridge in this pic, but not a mm is above bridge.

View attachment 738246

Found out the arbor was wrong for movement. I found another movement in my junk box and compared and subsequently replaced arbor. Now ratchet wheel seats correctly.
Regards.