Enlarge pocket watch roller hole ?

[Chopin]

I have a pocket watch that required a balance staff replacement. I've bought a NOS original one. The length fits, I even mounted it onto the balance and then onto the movement and everything checked out.

Upon trying to fit the roller I realized that it wouldn't fit. From research they made 2 versions of either balances or balance staffs or I don't know what exactly but the bottom line is that all parts are genuine, it's just that I have the roller or staff from one version and the rest from the other version (the hairspring collet also fits so only the roller hole is the issue).

You can't really find these parts and I don't want to invest anymore so I was wondering if it would be possible to simply enlarge the roller hole.

I don't have a lathe but I have ordered some mini-drills that come in all sorts of useful sizes. I would have to enlarge the hole by about 0.8mm.

It would have been helpful if I could find a really thin file to do this or maybe use some sort of a wire that behaves like a file but I doubt it.

Thoughts ? Suggestions ?

The pocket watch isn't an expensive or special one by the way so that's why I'd like to give it a go rather than invest a lot of money.

[oldhippy]

Use watch/clock broaches. Here is a link.

Measure the size you think you will need, and then look here. Use a little oil with the broach; it will help with the cutting. Broaches are tapered so be careful.  You need the cutting type that is all.

https://www.cousinsuk.com/category/broaches-cutting

 

 

[Chopin]

Oh this is exactly what I'm looking for, I think.

Are these basically "needles" with a texture similar to that of a file ? I can't find a close-up shot.

[wls1971]

6 minutes ago, Chopin said:

Oh this is exactly what I'm looking for, I think.

Are these basically "needles" with a texture similar to that of a file ? I can't find a close-up shot.

No broaches are five sided each side is a cutting face you insert and twist and the faces cut as you do so, they must be used at a perfect 90 degree angle to cut a perfectly centred hole, similar broaches are used in jewelling tools to enlarge jewel holes, the German ones that Cousins sell are cheaper than Bergeon and are very good the Indian ones I would give a wide berth. 

[Chopin]

And could someone give me any pointers as to how I can hold the roller into place ?

It looks like this. It would have been nice to have a vise with rounded jaws but I don't so...

[oldhippy]

If you have a watch vice hold it in that.

[Chopin]

15 hours ago, oldhippy said:

If you have a watch vice hold it in that.

I don't. Is there even such a thing ?

[oldhippy]

Perhaps I should have said watch movement holder. 

The second and third in the first row are the good basic ones. Here is the link.

 

https://www.cousinsuk.com/category/watch-movement-holders

 

[jdm]

1 hour ago, oldhippy said:

Perhaps I should have said watch movement holder. 

Chopin was asking about a way to hold a balance roller. Can't use a mov.t holder for that. 

[oldhippy]

I had a star watch movement holder and had no problem. Here it is, you can  screw it up and it will hold, the same as the movement holders I pointed out.

[Chopin]

The roller is very small. These holders have too large gaps to actually hold the roller.

I could use a normal vise (I have a small one) but it's hard to keep a round disk in place with a vise especially since, if at some point the roller moves or jumps out of the vise jaws I might damage it or break the roller jewel itself.

I'll figure something out I guess. Was thinking of making a hole in a cork screw or maybe a piece of wood (this one might be a bit more complicated...) but it still wouldn't really hold the roller in place if I want to drill the hole.

[vinn3]

Quote

a small drill chuck makes an exalent vice for round materal.  you can dub the jaws if they are serated .  vin

 

[oldhippy]

You should be ok with this tool.

https://www.cousinsuk.com/product/10mm-jaw-width-indian

[nickelsilver]

Opening a roller by 0.80mm is a lot, and it looks like a steel roller so going will be tough with a broach. Possible you don’t have the wall thickness to take that out even provided you have a good way to hold the roller and some buttkickin broaches. Best would be to turn down the staff.

[Chopin]

Sadly I don't have any tools to be able to work on the staff iself... Yes I believe it is steel...

[vinn3]

On ‎7‎/‎9‎/‎2018 at 10:07 AM, oldhippy said:

You should be ok with this tool.

https://www.cousinsuk.com/product/10mm-jaw-width-indian

  that is a hand vice,  would not a bench vise be better

[oldhippy]

I was thinking of cost.