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Jacot tool; part names and their uses .... ?

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Posted (edited)

Hello All;

I've read some of the recent replies of @JohnR725 and @nickelsilver regarding @VWatchie new Steiner Jacot tool, but it would be nice to get all the names of the parts, and their exact uses, in one place.

Seeing VWatchie's new shiny Steiner, I couldn't resist to search and stumbled over this Jacot tool, no it's not a Steiner, but it looks good none the less.




It has quite a few runners and some additional parts. The covered lanterns should be in good condition.

Could our experts on this forum be so kind to explain what the different runners are, why and when to use and what the parts 6 (?) & 7 (center broach) are / used for?

Thank you in advance 😉

Edited by Endeavor
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  • Endeavor changed the title to Jacot tool; part names and their uses .... ?

The parts 1,2,3,4, and 5 are what Bergeon and Horia (Steiner) call broaches, or broche in French. In my schooling they were called runners, and most English speakers I know call them that. The main body of the tool is usually called the frame. Number 7 is also called a runner in English (Horia just calls it a cylinder, also in French), but specified as the headstock runner- the headstock being the end of the frame with the pulley.


The different runners are for different sizes and types of pivots. In the above (and most sets), the runners with caps on one end are for smaller pivots, up perhaps 0.36mm. The caps cover the fragile lanterns, which allow working on the pivot ends. The short runner, with no lantern (#2 above) is for long pivots on 4th wheels that carry a second hand. They have longer beds and naturally make a tapered pivot. In the above set it looks like #3 could be an additional 4th wheel runner.


The runner with beds on both ends is for center wheels i.e. larger pivots. You would choose between headstock runner #7 or the one currently in the tool according to pivot size, usually one will do the normal range up to 0.30-40, the other up to the limit of the center wheel runner.


Finally, #6 is a limiter for the burnisher. It clamps onto the runner (tailstock runner, with beds), and can be positioned so that the burnisher can't ride up easily over a shoulder on conical pivots for example. They aren't very common, and I have to say I've never used one, even on teeny tiny ladies sized balance staffs. But I would say a useful thing to have!


The pivot gage is something that has always terrified me, and I've never used one of that style. It seems like a good way to mark or break a pivot. But it was a standard accessory for most Jacot tools. I much prefer a jeweled hole gage.

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@nickelsilver; Thank you very much 👍

I'll print it out and stick it, once the set arrives, in the box 😉

Indeed, I have had one of those (killer) pivot gauges before (throw it away, but now I'll receive another one 🙂 ) and they are ideal for ruining pivots, hence my DIY pivot-gauge:


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