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Elgin pocket watch stripped threads

LittleWatchShop
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LittleWatchShop Distinguished Member

LittleWatchShop

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This hole accepts the screw that holds the balance cock.  The threads are stripped.  Gotta wonder how that happened.

This is far more serious than the Lorsa thread issue I posted about last year.  I do not think closing with a domed tap will be enough.

Also, the cock may not allow a larger diameter screw unless I open the hole in the cock...maybe that is what I will have to do.

Thoughts/

IMG_8222.JPG

IMG_8223.JPG

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jdm Distinguished Member

jdm

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52 minutes ago, LittleWatchShop said:

Thoughts

I would try a bit of closing hole first.  If absolutely no holding to the screw, you will need to drill the hole bigger, fit a brass plug, then tap it for the original screw.

I don't know what the book says but having one I would do all that on the lathe with faceplate fixture to hold the plate, enlarge the thread hole, drill the plug, and tap it with the tailstock as a guide.

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LittleWatchShop Distinguished Member

LittleWatchShop

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4 minutes ago, jdm said:

I would try a bit of closing hole first.  If absolutely no holding to the screw, you will need to drill the hole bigger, fit a brass plug, then tap it for the original screw.

I don't know what the book says but having one I would do all that on the lathe with faceplate fixture to hold the plate, enlarge the thread hole, drill the plug, and tap it with the tailstock as a guide.

This sounds like a fun lathe project.  I do not have a faceplate fixture...not even sure what that is, but I will do some googling.  In the mean time, I made find a donor watch...you know...worst case scenario!

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jdrichard Distinguished Member

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40 minutes ago, jdm said:

I would try a bit of closing hole first.  If absolutely no holding to the screw, you will need to drill the hole bigger, fit a brass plug, then tap it for the original screw.

I don't know what the book says but having one I would do all that on the lathe with faceplate fixture to hold the plate, enlarge the thread hole, drill the plug, and tap it with the tailstock as a guide.

That’s exactly what I was thinking. Needs to be spot on target and the faceplate holder will do that. 

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JohnR725 Distinguished Member

JohnR725

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6 minutes ago, LittleWatchShop said:

Hoping it turns true.

You do know that it doesn't actually have to turn true don't you? In other words the Centering pin that comes in the backside really doesn't have to center. There's other ways to Center things on the faceplate like the thing I always find the peculiar name you use a wobble stick. There is a term you can look up then you don't need the thing that's in the backside and then he can also be absolutely sure you're running true.

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LittleWatchShop Distinguished Member

LittleWatchShop

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On 3/8/2022 at 3:58 PM, LittleWatchShop said:

Bought one on ebay. Hoping it turns true. Will see when it arrives. Excited to learn something new.

It arrived today.  Beautiful...should work great (not "user" proof though...lol).

QUESTION

How much greater than the screw diameter should the bushing diameter be?  If the screw diameter is 1mm what should the diameter of the bushing be?

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kibbler Member

kibbler

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3 hours ago, LittleWatchShop said:

How much greater than the screw diameter should the bushing diameter be?  If the screw diameter is 1mm what should the diameter of the bushing be?

I'm no machinist, but I would shoot for a similar excess diameter as the brass jewel settings have around the jewels.  That seems like plenty, and it would keep the visual appearance consistent

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nickelsilver Distinguished Member

nickelsilver

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Is that your first screw? That looks great! Looks like you tapped with a screwplate, Martin L? The thread pitch will be different to Elgin, but doesn't mean it won't work. Work it in with a little oil.

 

Which reminds me, how do mathematicians deal with constipation?

They work it out with a pencil.

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LittleWatchShop Distinguished Member

LittleWatchShop

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15 hours ago, nickelsilver said:

Is that your first screw? That looks great! Looks like you tapped with a screwplate, Martin L? The thread pitch will be different to Elgin, but doesn't mean it won't work. Work it in with a little oil.

 

Which reminds me, how do mathematicians deal with constipation?

They work it out with a pencil.

This is my 4th or 5th screw. I get a little better each time.

yes, a screw plate. I have 4 or 5...don’t remember which one. I tapped the hole using a tap Thea seemed to match the screw plate, but, in the end I think it was a little off, so the screw itself became the tap.

i am very confused be these screw plates I have and screws and thread sizes in general for watches.

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JohnR725 Distinguished Member

JohnR725

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29 minutes ago, LittleWatchShop said:

i am very confused be these screw plates I have and screws and thread sizes in general for watches.

I suppose the confusion has to do with trying to figure out the standards?

1 minute ago, nickelsilver said:

But the U.S. companies generally had their own threads- each company had its own threads.

Darn somebody beat me to the answer?

Yes everyone assumes their standards for screws sizes used in everything on the planet. But all the American watch companies had their own sizes. I think only Elgin and Waltham ever published their sizes everyone else it's a mystery.  

It's why you can have a whole bunch of boxes of screws and try to replace one find that none of them will fit.

 

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LittleWatchShop Distinguished Member

LittleWatchShop

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On 3/8/2022 at 3:54 PM, JohnR725 said:

I thought for anyone else that wants to know what a faceplate is I have some images.

watchmakers faceplate page 3.JPG

face plate page 2.JPG

face plate page 1.JPG

@JohnR725, I have one of these but it was missing the index pin that runs through the center.  So, I recently purchased some 4.5mm round stock to make one.  The round stock is a perfect fit except that my faceplate(s) have a key inside the collet housing...much like the spindle of a WW lathe.  Seems to me there is no good reason for this key>  The index pin is symmetric in the theta plane.  There seems to me no reason for key in the collet.  Any thoughts???

The key is made of soft metal and I can punch it out easily enough.

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