Sheared Screw on AS 1200

[Nunk]

I just knackered my crown wheel screw by over tightening.  The top sheared of and part of it is now stuck in the mainspring barrel bridge.

What is the best way to sort this out.   Buy a new bridge ,  drill it out ???  Where is the best place to source vintage parts?

I have only started learning how to repair watches.  Having lots of fun but it can be quite challenging.

 

thanks

 

[vinn3]

Quote

 

welcome to the forum. that topic is well covered in early posts.  look thru early posts.

[Nunk]

I had a brief look.   Could not find anything ???

 

[wolfwatchwerks]

Alum bath. Don't go digging around and drilling stuff unless you're sure of yourself.  Alum is used to dissolve the steel screw without damaging the brass plate or threads. Crown wheel screw is obviously vital. I hazard to say a very large lesson has been learned here. Depending on the movement, it may be impossible to find, or easy. Sometimes a scrap movement of the same caliber can yield the parts you need. Sometimes we create scrap movements that we get rid of to others to use for parts. (A-hem) If you're a pro you can make your own parts. It all depends on what you have and how rare or common it is. Good luck, hope you can get it worked out.

[rogart63]

Welcome to the  club. Alum or maybe vinegar  to remove the pieces of the screw with. Left hand screw maybe? Or get a new used  bridge. Or a donor movement. 

Edited January 9, 2018 by rogart63

[StuartBaker104]

The good news here is that when you’ve got the screw out, replacements are available...

https://www.cousinsuk.com/category/as-movement-parts

 

[Nunk]

yeah lessons learned.  The more things I break the more I learn.

 

Thanks for help.

 

 

[anilv]

Use a rigid pick and try to either back it out or screw it out the other side.

The tension caused by the threads pulling away from the screw head is what holds the crew.. when the head is broken off completely the tension is removed. I find that unless rust is involved, most screws respond well to this method.

You are aware that this will most likely be a left-handed screw right?

Anilv

[Nunk]

I was thinking of screwing it from behind

I am aware it is a reverse screw.  I sheared it off due to using a larger screwdriver than normal which increased torque slightly.   I have to get in the mindset that I am working on small fragile parts and apply a bit of patience.