Re-pivoting

We’ve not been very busy posting lately, but that’s mainly because we are very busy at the workshop. Also, as you can always check out what we are working on at any moment in time, we felt that most our readers are using that feature to see what’s happening.

Today, I’m posting a more technical post, which might benefit my colleagues, rather than my clients. Anyway, it’s probably interesting to see what can be done.

Broken pivots are a regular occurrence, and on the left, you can see the two autowinder wheels from a Heuer 12 movement. The one on the left has a broken pivot.

If a part is available for reasonable amounts of money, buying a new one is always the best solution. But if the part isn’t available, or very expensive, a repair is in order.In order to fit a new pivot, the broken pivot has to be removed, and a hole has to be drilled to accommodate a new pivot. We are looking at drilling a 0.2mm (!) hole here… The tool of choice is an end mill.

This is looking very promising, and the crucial part of the operation. I have managed to drill a 0.2mm hole into the wheel, and I can now fit a new pivot into it.

Using an old 0.6mm screwdriver blade, I turn a new pivot on the lathe. It’s stepped, and has a larger diameter of 0.2mm to go into the hole of the wheel, an a stepped down 0.17mm part which is the new pivot.

Just to get an idea of size – on the left my index finger (in a nitrile glove). You cough, and the part is gone.

The new pivot fits nicely into the hole that I drilled, and just to make sure, I put a tiny drop of superglue into the hole before fitting the new pivot to make sure it stays where it’s supposed to stay.

This repair is pretty much at the limit at what you can do size-wise. I’ve got a 0.15mm end mill, so I could drill an even smaller hole, but that would definitely be the smallest I would attempt to go …

One thought on “Re-pivoting

  1. Great idea to use an endmill instead of a carbide drill. I find Loctite 638 to be better than superglue, slower and easier to clean the excess with Rodico, but each to his own! Thanks for the post.

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