Miniature carriage clock

[HectorLooi]

If you remove all the carbon steel components of the balance cook, you could soak it in alum. It will take a couple of days.

[MikeEll]

1 hour ago, HectorLooi said:

If you remove all the carbon steel components of the balance cook, you could soak it in alum. It will take a couple of days.

the screw is actually screwed into a steel regulator arm, so I'm guessing that wouldn't work in this case.  I'm fascinated by the idea though, I've never heard of alum before now.

4 hours ago, oldhippy said:

If there is nothing to grip. How are you going to cut a slot. From the photo I can't see if it is protruding or not.

well I was thinking I could cut a small slot across the broken screw and the piece that its stuck in.  So long as the screwdriver is narrow enough I'm hoping it might be able to turn the screw.  As a backup, I might simply try and drill another hole in the hairspring stud and just leave the broken screw where it is.

[nevenbekriev]

It is possible to cut a slot, but the screw is so thin, that I wonder what will cut that thin slot. Then, will the screw untighten by the force of that small screwdriver if it was so tighten that it broke off? If You pres the stud out, then it will be easier, as the screw will be not tighten any more.

The standard way is to drill a hole thru the screw with smaller drill bit, to press tapered broach in and try to unscrew, and as a backup - to drill with bigger drill bit and cut new thread for bigger screw

[oldhippy]

Have you tried knocking the stud out? That might loosen the screw. You could also try some penetrating lube. A screw slotting file I expect it will be too big. One thing I used to use was an old watch oilier finding a rough part and try to unscrew it that way, It never worked all the time but you might like to give it ago.  

[MikeEll]

thanks guys.  I did manage to press the stud out.  The stud is quite a tight fit still, so might simply try to press another stud in, positioning the hairspring hole at a suitable depth, then just leave the old screw where it is.  No real need to remove the screw I guess.