Jump to content

Removing broken timing screws

JohnC

By JohnC
in Watch Repairs Help & Advice

 Share

Recommended Posts

JohnC WRT Addict

JohnC

Posted
Posted

Hi all,

I need a bit of help here. In trying to turn a mean time screw I have sheared off the head on my 18s Waltham. Pics attached. Not worried about the ruined screw but I need to find a way to safely remove the remainder. It's not protruding at all on the outside so pin vise is not an option. Any help appreciated. Thanks.

FB_IMG_1621525370290.jpg

FB_IMG_1621525379326.jpg

nickelsilver Distinguished Member

nickelsilver

Posted
Posted

It will have to be drilled. As you probably don't have a jig boring machine, the safest bet would be to drill it out by hand, rotating the drill in a pinvice. Most important thing is to get it in the center of the broken screw, for this you can take a piece of carbide or hard steel and grind 3 flats at 120 degrees to each other, at about a 40 degree angle to the end. Use this to carefully make a start pip, then drill through. Move up in drill size until you are right at the threads, you can then pick out the remaining bit. If it goes as planned the threads in the balance will be OK and you can fit a new screw.

  • Like 2
  • Thanks 1
nickelsilver Distinguished Member

nickelsilver

Posted
Posted (edited)
6 minutes ago, JohnC said:

@nickelsilver
thanks. Others have recommended drilling enough to insert a broach, and then attempting to screw it either out or through. Thoughts?

Yes, that can work, but don't break the broach!

 

Sometimes if you're lucky the drilling will actually screw it on through.

Edited by nickelsilver
  • Like 2
JohnC WRT Addict

JohnC

Posted
  • Author
Posted
1 hour ago, nickelsilver said:

Yes, that can work, but don't break the broach!

Oooh yes, good point. Okay, first some oil and then I will attempt that. If it seems like the broach will break I'll try to drill out to the inside diameter of the screw. Many thanks. Just swapped the staff so the last thing I want to do is source a balance. I want to get past the "balance complete" stage.

Flagstaff Member

Flagstaff

Posted
Posted

I had a broken screw in a mainplate recently - there were some female threads visible so I screwed in a screw with the same thread (full length undamaged screw) which grabbed the end of the broken screw and it came out fairly easily. Perhaps I was lucky, and it does rely on the broken thread having little or no tension on it - if the threads are distorted and tight it will likely not work.  

It was a much better solution than trying to drill it out without damaging the threads. It does rely on having a few "empty" threads though. Not sure from your photo if you have any? 

  • Like 1
Nucejoe Distinguished Member

Nucejoe

Posted
Posted

Hi John,  In case there is some empty thread, a quick but imperfect approach is to file down a new screw just short enough to fit what thread is left, try to shelac the screw thread to keep it from loosening.

 

 

  • Like 1
 Share
Go to topic listing

  • Recently Browsing

    • No registered users viewing this page.

  • Topics

  • Posts

    • RichardHarris123
      About repair watch's jewel.

      By RichardHarris123 · Posted

      Hello and welcome from Leeds, England.  Photos please. 
    • RichardHarris123
      New forum member, new learner

      By RichardHarris123 · Posted

      Hello and welcome from Leeds, England. 
    • caseback
      School Me Please: Sliding Mainspring Bridles

      By caseback · Posted

      This is the old/first(?) way for making a mainspring for an automatic. "Evolution-wise" it is an logical first step forward from a standard spring. Usually these are indeed replaced with a new spring with an integrated/fixed bridle. Lubrication as you would do with any automatic.
    • FabioBastardo
      Unknown watch movement logo. Very interesting

      By FabioBastardo · Posted

      Thank you. I was informed it was a cheap worthless Lack watch from India. It’s in a small mens watch looks to be around 1930 odd   Cleaned the movement and it’s going really well. Keeps good time.  This is a great site. Mystery solved. I’m obliged. 
    • RickTock
      School Me Please: Sliding Mainspring Bridles

      By RickTock · Posted

      I'm working on a Schild AS 1250 (a 'bumper' automatic) and it's the first time I've seen a mainspring like this. It has what looks like a regular manual-wind mainspring with a 'hook' at its outer extremity. On a manual-wind watch that 'hook' would engage with a 'hook' in the barrel wall to prevent it from rotating. However, the AS 1250's mainspring does not engage directly with the barrel but rather with a 'sliding bridle' that sits between the mainspring and the barrel wall, and evidently facilitates the slip necessary in an automatic. I'm not sure what advantage this two-piece configuration provides, but it highlights a gap (one of many) in my horological knowledge. I'm not sure if 'hook' is the correct term as used above, but please see photo below to see what I mean. Therefore, two questions please. 1. What is the proper way to lubricate a barrel from an automatic watch with a sliding bridle? My guess is the same as any automatic ms/barrel (e.g, a few dabs of braking grease on the interior barrel wall). What do the experts say? 2. I purchased a Generale Ressorts GR3472X mainspring, made for the AS 1250. It looks like the bridle is included and I don't need to salvage and re-use the old one. Is this a safe assumption? Thanks for the advice. If you have any other wisdom you'd like to share about separate sliding mainspring bridles, I would be very interested. Cheers!
×
×
  • Create New...