Okay here is the last part...
The next step is to make sure I have the tools needed to turn that small area, and I took one of my smaller HSS gravers, and ground it down – not quite there yet but this shows the original size on the right, and the ground down one on the left:
Now ready:
After performing some test cuts on the spare bridge, I get the bridge I want to fix – spare on the right and the original bridge from the watch on the left:
The main plate was left on the chuck, so all I had to do was unscrew the test bridge from the plate, and screw the good one in place:
Making the cut – took all of about 30 seconds:
Here you can see that the raised boss that the crown wheel rides on has now been turned flat again:
I’ve now removed the bridge from the plate on the lathe, and taken it back to the bench. It’s been mounted and here’s a video showing the movement now:
You can see that it is still freely moving, but doesn’t tip as it did before. So the wheel cannot tip enough to allow the teeth of the crown wheel and winding pinion to disengage from each other.
So this problem is now solved. However that’s not the only issue this watch has – the original main plate for this was is badly worn, and as you may be able to see here the center hole is worn oval, and this has allowed the center wheel to tip so much that the cannon pinion teeth have carved away a bunch of material at the red arrow in the middle (enlarged view bottom left):
So back to the parts bin to find a good plate. I also looked at many train wheels, etc. to find a set that were in good shape:
And here a final test to make sure it could be fully wound without slippage between the winding pinion and crown wheel teeth:
So I hope you enjoyed seeing how one small problem on a vintage watch is resolved. Now the real work getting the movement performing properly can be started.
Cheers, Al
Click to expand...