Barrel arbor screw broken

[p2n]

Had a Leonidas GSTP pocket watch I got from ebay several years ago that came in pieces. Just starting to have a look though and there are two problems I can see immediately. The first and probably the biggest for me, is the barrel arbor screw has been sheared off.

 

Any idea how I can either get the remains out or get a new arbor?

 

(The other is it's missing a canon pinion)

 

 

[JohnR725]

2 hours ago, p2n said:

Leonidas GSTP pocket watch

always nice to give a picture of your watch on a watch repair discussion group we really do like to see pictures of watches.

[p2n]

Not much to see at the moment...

[JohnR725]

your mainspring is a nice pretty blue color. That tells me it's probably set it should be replaced once you take care of the other problems. But of course you don't really know until you take it out occasionally blued steel Springs will still looked beautiful but only occasionally and typically they do have to be replaced.

 

[rehajm]

...something like this is probably your best option for the arbor.

[p2n]

I did read that thread. It seems like the best and only option I've got at the moment. Was seeing if you could buy small left hand drill bits but they don't seem to come small enough for that.

[JohnR725]

sometimes with broken screws if you use penetrating oil you can loosen them up sometimes you can poke at them and get them to unscrew. It may be possible with the arbor to basically drill it out It and put a new screw and. On the other hand if you had access to a watchmaker's lathe to do that in the first place you can just make a new one.

[oldhippy]

You have a few tips to chose from in getting that screw out. 1, you could use Alum and leave it for a few hours. 2, sometimes you can work it out by using a pair of old tweezers or and old screwdriver trying to unscrew it. 3, Try drilling it out you need to drill very slow with some lube if not the drills will snap.  

[p2n]

I didn't think I could use alum since the arbor itself is steel.

I've tried putting it in the ultrasonic in a small jar of solvent and 3-in-1 oil to see if I can loosen it, tried afterword with a small screwdriver to see if it was going to co-operative and it refused. It's got to be stuck tight to shear the head off.

Think I'll mount it in a collet chuck/pin vice and chuck that in the mini-lathe then I can slowly drill it. (If I could afford a watchmakers lathe I'd get one!)

Edited May 16, 2023 by p2n

[Neverenoughwatches]

2 hours ago, p2n said:

I didn't think I could use alum since the arbor itself is steel.

I've tried putting it in the ultrasonic in a small jar of solvent and 3-in-1 oil to see if I can loosen it, tried afterword with a small screwdriver to see if it was going to co-operative and it refused. It's got to be stuck tight to shear the head off.

Think I'll mount it in a collet chuck/pin vice and chuck that in the mini-lathe then I can slowly drill it. (If I could afford a watchmakers lathe I'd get one!)

Personally i would fashion a small driver into some kind of extraction tool. Drilling it you are driving it further in and would be forced to drill it all out and hope not to catch the arbor threads or break the drill. If the drill breaks you are shafted ( drill ? shaft ? yeah whatever  ).  Backing it out you might just get lucky after a good long soak in penetrating oil. 

[p2n]

2 minutes ago, Neverenoughwatches said:

small driver into some kind of extraction tool.

What do you mean? Hack an old screw driver bit into a tool?

[Neverenoughwatches]

39 minutes ago, p2n said:

What do you mean? Hack an old screw driver bit into a tool?

if you make a start on the broken screw with a drill so you just have a shallow hole this will give a sharpened screwdriver blade something to bite into so you might be able to back the screw out. Sharpen the driver something like a tapered triangle or square. Never mind forget making the driver just use a tight fitting broach in the hole you made. Voilà one screwextractor

Edited May 16, 2023 by Neverenoughwatches

[p2n]

Ah see what you mean. WIll try that and let you all know how it went.

[Neverenoughwatches]

5 minutes ago, p2n said:

Ah see what you mean. WIll try that and let you all know how it went.

A tapered tool will jam up and bite into the screw as you push it in. Steady as she goes though and be mindful of whats happening to the screw . If its turning out great but if the driver or broach is starting to cut then stop as you might end up losing the arbor threads. A good soak for a day or so before you attempt,  if you are fighting against a corroded screw then your only option might have to be drilling it out. 

[p2n]

Earlier today I heated the arbor a bit and dropped it into my solvent and oil mix. The idea being the cooling will draw oil into the thread. I'll run it through the ultra sonic a couple of times before I try and move it again. I like the idea of making a small drill hole first and trying to move the screw. It was seized solid so I may end up having to drill it out and lose the thread. If that happens I'll have to re-tap it and use an overize screw.

If this were normal size (M4 or over) I'd be fine - done it plenty of times, but this size is something new to me!

[Neverenoughwatches]

13 minutes ago, p2n said:

Earlier today I heated the arbor a bit and dropped it into my solvent and oil mix. The idea being the cooling will draw oil into the thread. I'll run it through the ultra sonic a couple of times before I try and move it again. I like the idea of making a small drill hole first and trying to move the screw. It was seized solid so I may end up having to drill it out and lose the thread. If that happens I'll have to re-tap it and use an overize screw.

If this were normal size (M4 or over) I'd be fine - done it plenty of times, but this size is something new to me!

The fear is breaking the drill, if that happens then you have a bigger problem of a piece of hardened steel in there. Its often as you are just breaking through what you are drilling, which is  probably when the drill bit receives the most torque and its done the most work. Happened to me only last week would you believe hand drilling the back end of the eye of a needle with a cheap carbide drill. It completely shattered just as it was coming through the steel,  ps  dont buy cheap carbide drills they are crap.

[p2n]

Got the little shit out (three carbide drills shattered). It's a left hand thread! Sort of explains how it got like that I suppose.

The arbor has a square top so I didn't think a reverse thread screw would be needed there?

Are there left hand thead die plates for making replacements for something like this?

 

 

[RichardHarris123]

A new one for me, I haven't come  across a left hand thread on the barrel arbor. 

[Jon]

Had a left handed ratchet screw the other day on an AS 1677 ladies watch. You don't come across them often, but when you do it always throws me! Why the hell a left hand thread on a ratchet screw? Seriously! I've even come across left handed dial screws. They even had three slots cut into them!

27 minutes ago, p2n said:

Got the little shit out (three carbide drills shattered). It's a left hand thread! Sort of explains how it got like that I suppose.

The arbor has a square top so I didn't think a reverse thread screw would be needed there?

Are there left hand thead die plates for making replacements for something like this?

 

 

Nicely done there!

I have removed a broken screw before by cutting into the barrel arbor with a depth/coping saw until it puts a very slim slot into the broken screw and then used a screwdriver after oiling and ultrasonically blasting it to remove said screw. The arbor has a slot in it after that, but it doesn't affect its use. The less you cut into the arbor the better, but the main thing is, it works and the arbor can be re-used afterwards. Pretty sure I read this years ago in a Donald de Carle or Henry B Fried book. The great thing about these two pioneers of wristwatch work is, they weren't afraid to take it to another level. A lot of their techniques are what I use today and teach to my students.

If I could have anyone at a dinner party alive or dead, it would definitely be those two guys! Donald and Henry.

[Knebo]

4 hours ago, Jon said:

Had a left handed ratchet screw the other day on an AS 1677 ladies watch. You don't come across them often, but when you do it always throws me!

Indeed! Unmarked left handed ratchet screws - a scandal 

I just tonight found out the hard way with an old AS 574. The screw broke off. So beware with that calibre, too! 

(Thankfully I have two incomplete AS 574 movements and am combining them into one that works - and so I have a working spare barrel arbor and screw).