This is an fusee English lever pocket watch. The customer said that it was only running for a few minutes and then stopping. On first inspection the amplitude was almost non existent but strangely was running. I presumed a good service would resolve this issue BUT alas the same issue. I stripped again and inspected every part with a microscope and found a bent safety pin + the banking pins had been bent. Apart from this I could not find anything. The balance pivots show some scoring but just a tiny touch it swings fine. Believe it or not, the amplitude now (see vid) is twice as much as what it was. My suspicion is the pallet is not the original and the horns are just a touch short so the impulse pin is not swinging the hairspring on impulse. Just wondering if anyone has come across this error,I'm a bit lost at present.
Next step was to broach the pivot hole out to fit the pivot on the wheel. This was another "first" for me, so I read up, took my time and went for it. Cutting slowly from both sides, bit by bit and constantly try-fitting the wheel to check for fit and to make sure the hole was true. Also, refitting both plates with the wheel fitted to ensure there was no binding points.
Finally, using the smoothing broach to harden the pivot hole, bearing surface.
The bush was fitted from the inside, again as required, without issue.
I have an engineers flat surface which I used to get a true fit. Also, I had an appropriate sized flat headed stake in my staking set, so fitting the bush was a straightforward job.
Apologies for the photo from the outside of the plate, as the focus point was off.
Next step, was to take the hole out to the wanted size of 4.47mm.
Although I had damaged the smaller cutter in the process of the initial step, the broach had worked correctly as I learned how to use it and the hole looked great for this next step. I was cutting from the back of the plate, as required, and using the new broach worked as I now expected it would. This photo shows the resulting hole once done, with hole now ready to accept the new bush.
OK - So the job got done!
I know old hippy was interested in the end result, so in the interests of "full disclosure", here it is...
The photo of the worn bush appeared in an earlier post, so I won't repeat it, but needless to re-iterate, is was badly worn. This is my first attempt at re-bushing, so will expect to have some "opportunities for learning the hard way".
Ready to cut... I had filed a little on the opposite side of the wear t make an oval, trying to centre on the original pivot centre. I needed to fit a 4.5 mm bush with a 2.00 mm pivot hole. I bought a 4.47mm broach and a 3.97mm. The reason for the smaller cutter was that I was not sure if I could (or should) go straight to the correct size in one step. The photo shows the smaller 3.97mm cutter ready for the first cut.
First learning issue: I had a lot of issues with the broach binding in one point on the hole, causing the broach to seem to want to cut offset from where I wanted it to go. I started wondering If I should have started broaching with an even smaller size first. Maybe someone could advise...
In the end, I managed to get the cut straight (I was hoping anyway) but in the process managed to damage one side of the cutting edge, near the tip of the broach, where it caught on the side of hole and started to dig in. Almost certainly knackered a £14 broach, but there you go, everyday is a learning day!