fly arbor with broken pivot

[gerene]

I am working on a French movement from an “Oeil de Boeuf” clock and found that the fly arbor has the pivot broken off. I might have done this myself but then it happened unconsciously 🙄 .
Now I am faced with the problem on how to fix this and therefore I would like to have the advice of more experienced people.

The dimensions are: diameter of the arbor 0.9 mm and for the pivot 0.4 mm (at least the remaining pivot). I am reluctant on repivoting, given the small diameters of arbor and pivot and the fact that I have never done any repivoting before.

I really need some advice on this. For this clock I broke one of my rules: don’t work on someone else’s clock. This clock is from a friend who insisted on me servicing his clock and I finally agreed on doing it.

Hope someone can help me out.

Jan

[chris mabbott]

I hear what you’re saying Jan, I have the same rule myself, so I feel your pain!

I think the only option, other than making a new one, or finding a similar part, is to repivot!
Bob shows the procedure in one of his videos.

I did the same on a waltham 4 th wheel pinion about a month ago, I was so angry with self that I didn’t touch another watch for days!

[gerene]

Thanks Chris. I just feel very uneasy with the procedure. I never did it before and on top of that this is a rather small arbor .
O, by the way, I spent most of last week and the beginning of this week in Marbella, which should not be too far away from your place.

Jan

[bernie weishapl]

One other concern at least on the ones I have worked on these pivots are extremely hard and difficult to drill. You could chuck that arbor up right up to the pinion which would give you excellent stability. The last one I did several years ago if I remember correctly is I used a small center drill to start the hole and then used a carbide bit but be careful and don’t use extreme pressure when drilling. You break it in the arbor and it almost certain a new arbor would have to be cut. Not trying to discourage you from doing it but just use caution. Slow is good. Good luck.

[namonllor1953]

Hi Jan,
What a great oppertunity for growth!!
I know the uneasiness you’re feeling. I go through it everytime I go to do something for the first time. It’s pretty normal. May I suggest turning a piece of scrap rod down to .9 mm, and drill and pivot with .4mm music wire. I know that once I try something on scrap material, when I go to do it on the real piece, there’s a sense of familiarity and it usually works out well.
Go slow and easy does it. You can do it!!
Ren

[gerene]

Thanks Bernie for the advice. The arbor is indeed very hard. I might try to use a very small center bore (the smallest I have is still 1mm) to start the hole. I was wondering if annealing the arbor first would help. I don’t have any experience with annealing (or other heat treatment) either, so some advice on this would be really appreciated as well.
Yes Ren, I will try the procedure first on a piece of steel with the same diameter. This is really good advice. In fact I just tried to drill with a .4mm carbide drill and I ruined my drill in less than a minute. I will now have to wait for new drills coming in since I only had one, I bought a set from ebay which had one of each. Up till now the 0.3 and 0.4 are gone… 😳
I ordered 10x 0.3, 0.4 and 0.5 from ebay, but they have to come from China, taking some time. 😡

In the mean time I am rewatching Bob’s video on repivoting, thanks Chris for pointing that out to me.

Jan

[chris mabbott]

@gerene wrote:

I was wondering if annealing the arbor first would help. Jan

Jan, this is a good question and one I’ve been wondering about myself.

Bernie, what is the smallest size center drill that you’ve found, looking for a micro set myself?

[arutha]

Hi Jan,
make sure where the pivot broke off the face is clean i.e. stone it flat. Find centre with a sharp graver, then go in very gently with the carbide drill bit. If you are not on centre with the drill bit you will see it wobbling as it tries to cut. It doesn’t hurt to go a little over size, you can then cut back the new pivot with a graver to the correct diameter and then polish it. If you still have no luck you can post me the arbor and I will do it for you
Paul.

[namonllor1953]

Great advice Paul,
It’s a bit tough for me to find center with a graver 100% of the time. Bob shows a little tool he made on one of his videos, a Magic Center Finder, and it works like a dream every time.
Here’s a photo of mine:
and

[arutha]

I had forgotten all about that tool, I just got used to doing it with a graver. Thanks for posting that up Ren, they do make life easier!
Paul.

[bernie weishapl]

Ren I can tell ya on a French pivot the your tool won’t work. The steel in the french clock is much harder than that tool. So I do like Paul does and use a carbide graver to start the hole of a center drill.

Chris I got a slew of center drills when I bought my lathe many years ago. I mean I got some that you need a loupe to see the end. I have never tried a watch pivot as I was always able to find a replacement gear even if I bought a parts watch. Sorry.

[gerene]

Thanks everybody for the good advice.
Paul, I might take you up on your offer. I will try a little more, but given the fact that it is a rather small arbor and it is not my clock, I might post the arbor to you. I prefer learning repivoting on something less critical. My fear is breaking the drill in the arbor.

Jan

[namonllor1953]

Hi Bernie,
Why couldn’t the tool be made of drill rod and if it were, wouldn’t that work??

[chris mabbott]

Bernie, that’s interesting. I’m also guilty of not fabricating this center finding tool yet.
I’m curious though, what did Bob suggest as the material that it should be made from?

Would you say that if it, the tool, were made from similar or harder material than that which it marks, then it might function better?
I’m just wondering if it could be made from a carbide drill bit ?

Jan, I feel that if you took up Paul’s kind and generous offer that it would be better and less stressful for you personally. Not because you wouldn’t be able to do it, but if you are the same as me, I’d probably be so focused on NOT breaking something, that I would anyway.. haha

Paul, that’s very nice of you to offer that buddy..

[chris mabbott]

Hey Ren,

Looks like we had the same thought at the same time 😆

[Author]

Posts