Anyone ever made themselves Pivot Gauges?

[Tmuir]

I'm setting myself up to start to learn how to make balance staffs.

I've got a balance staff that has broken both pivots off so I need to measure the jewel holes to get the correct size to make the pivots.

I cant afford the price of a Bergeon 30333 pivot gauge set, so I am thinking about making some pivot gauges up which would also be good practice for myself.

I plan to do the initial turning on my watchmakers lathe and was thinking of finishing on my Jacot tool.

The one issue I have is the Jacot tool is made for turning a shaft with a wheel on it, which obviously I won't have.

Anyone got a good idea of something to make up like a miniature lathe dog to fit onto 1 or 1.5mm rod so I can use my Jacot tool?

For those that don't know what I mean by Pivot gauges Raul Horology's website has a great post on making them, with far better tools than I have available to me.

http://raulhorology.com/2012/04/pivot-gauges-with-straight-and-conical-pivots/

[oldhippy]

I never needed to make one. Searching around on the net I came up with the same site as you. Why can't you turn them on your lathe?

[nickelsilver]

As I guess you've seen, these are a standard exercise in many watchmaking schools. If you are making them for actual use, it's not necessary to make both conical and square shouldered, but probably a good idea to make them conical as they will be less likely to break.

In schools they are usually turned entirely between centers, but you can turn them up in a lathe no problem. For finishing them in a jacot tool, you would normally use split carriers like the one in the photo from Horia. I believe Bergeon still makes a set as well, and you can make them yourself (the Adventures in Watchmaking blog has a good explanation).

In little balance staff pivot sizes you don't want to use a micrometer to measure, but rather a gage made up of hole jewels in .005mm increments (or smaller). A micrometer can very easily make a micro flat on a pivot even with a very light touch. I think for your gages you can get away with it though, as the flat would be more of an issue on a running pivot than a gage.

[Tmuir]

I can turn them on my lathe, its just the final polishing of the pivots I cant do on my lathe as I do not have a Jacot tool for my lathe.

Thanks for the website Nickelsilver.

Yes Cousins has the Bergeon tool and clamps, but at £150 or so pounds I would rather put the money to greater use.

A pivot gauge like you mention has been on my list for a while, but I haven't been lucky enough to get one yet.

I've got a pretty good selection of tools and equipment, but still a long way from a complete set.

[oldhippy]

You should be able to burnish them in a lathe.

[Tmuir]

I want to make a selection of pivots from 0.08 to 0.12mm going up in 0.01mm steps

I would be worried without a Jacot tool I would snap the pivot off if I tried to burnish them.

 

[oldhippy]

I’m sure if you take your time and don’t use too much pressure you should be fine.

[nickelsilver]

Making the drive carriers and opener is also a typical school project, doesn't have to be elaborate just functional. You could just make simple split carriers and open them with a twist of a screwdriver on a bench block.

[jdrichard]

Unusually finish them off with a Jacot tool just to avoid snapping off the pivot in the Lathe....chicken. I do have a jewelled ruler to measure the pivot size. I bring it down to around .14 in my Lathe and shave the rest off I’m the Jacot. Perhaps I can more brave as well. I did pick up a set of Pin Gauges:)


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