Fixing stripped thread

[graemeW]

Doing some assessments today on the watches I have waiting in line.

This is another 108 year old watch, a 13 ligne buren. No idea what movement it is.

It runs. The banking pins have been messed with and for some reason the bottom cap jewel for the balance seems to be glued in. But I'll worry about that later.

The main issue this watch has is the little piece, whatever it's called, that retains the crown. The thread has stripped out. Watch is filthy, and it seems someone has tried to glue the screw in.

Any thoughts on how to fix this?

If it was bigger, and that thread was m3 or larger, I'd have no trouble. Id drill it out, fit a bush and retap. But this is a watch, and that is tiny.

I don't have a staking set, but plan to buy one. I do have a lathe though, so could make punches if I need to close that hole up. I couldn't 're tap it though.

What would be the proper way? I'm just going to assume I won't get a replacement piece.

I could probably make a replacement if I really tried, but couldn't tap it.

I get a feeling I'm going to be trying to find out what the thread is and be buying a tap.

I'm not super sure there is enough meat to close this hole up to 're tap anyway.

Any thoughts on options?

 

If it was 2 inches long, I'd weld it up. But it's not

I could hard solder it, I have proper high temp silver solder. I could maybe braze it, but id be worried about turning it into one tiny molten blob. I also suspect the thread wouldn't hold up to much use.

[GPrideaux]

The part is called the setting lever. In the standard Swiss numbering scheme it's part 443. IF you can identify the movement you might be able to source a replacement part. (There is a forum here called "Identify this movement or watch".)

[graemeW]

15 minutes ago, GPrideaux said:

The part is called the setting lever. In the standard Swiss numbering scheme it's part 443. IF you can identify the movement you might be able to source a replacement part. (There is a forum here called "Identify this movement or watch".)

Ah, setting lever, thanks.

I didn't realise the swiss has a set  numbering system, that's amazingly organised!

I have been searching to work out the movement but no joy yet. Ill put a pic in the relevant place.

Replacement part would definitely be the easier and best way to go.

[praezis]

How about the setting lever screw and its thread?

[graemeW]

4 minutes ago, praezis said:

How about the setting lever screw and its thread?

They are fine. I took the setting lever out to check and to get a good look at it's shape. I have been searching for setting levers to see if I can find one that matches, and work out what the movement is from that. But no joy yet.

[mikepilk]

1 hour ago, graemeW said:

Ah, setting lever, thanks.

I didn't realise the swiss has a set  numbering system, that's amazingly organised!

I have been searching to work out the movement but no joy yet. Ill put a pic in the relevant place.

Replacement part would definitely be the easier and best way to go.

They do, and it's very useful. Have a look at this -

Swiss part numbers.pdf

 

[AndyGSi]

41 minutes ago, graemeW said:

I have been searching for setting levers to see if I can find one that matches, and work out what the movement is from that. But no joy yet.

Do you know about BestFit as a place to start when trying to find movement details based on the setting lever?

[graemeW]

2 minutes ago, AndyGSi said:

Do you know about BestFit as a place to start when trying to find movement details based on the setting lever?

I don't. Quick Google didn't throw much up

[mikepilk]

Can you post a pic of the keyless works to help ID ?

[AndyGSi]

Can you post a photo of all the parts associated with the setting.

[graemeW]

I put the pieces back in loose

Overall

Each side of the setting lever

 

The screw. The threads are full of glue, but I think they are ok

 

It's a simple part, if I can't find one, I'll make one. Just need to be able to tap the thread. I don't even know if watch screws of this age have set thread sizes or if they are all individual.

 

Edited January 26 by graemeW

[AndyGSi]

So part of it from my earlier post looks like what they called Buren Old

[graemeW]

13 minutes ago, AndyGSi said:

So part of it from my earlier post looks like what they called Buren Old

It does. The other parts aren't the same though.

[AndyGSi]

So this is your movement which at least gives an approximate date and I've also seen another similar dated 1922.

https://www.vintagewatchroom.com/product-page/1918-buren-sterling-silver-gents-trench-watch

Edit

Here's another dated 1916 but still no further on with a number.

https://www.worthpoint.com/worthopedia/antique-wwi-1916-buren-solid-sterling-532184454

Edited January 26 by AndyGSi

[graemeW]

4 minutes ago, AndyGSi said:

So this is your movement which at least gives an approximate date and I've also seen another similar dated 1922.

https://www.vintagewatchroom.com/product-page/1918-buren-sterling-silver-gents-trench-watch

Edit

Here's another dated 1916 but still no further on with a number.

https://www.worthpoint.com/worthopedia/antique-wwi-1916-buren-solid-sterling-532184454

Sorry, yes, I should have specified. It's in a silver case halmarked 1916. I didn't specify as I assumed they started earlier and finished later.

It's a complete running watch, just needs a setting lever, the crown fixing or replacing (that will be another nightmare I don't doubt) and a strap.

It's a black dial trench watch. I have 4. I'm a little obsessed with them. They are the whole reason I started learning watch repair.

Measured the screw, 0.77mm. Presumably worn, so I guess it's 0.8mm.

This seems a thing. Taps are available. Cheap tap sets are available. I assume they will come in handy if I keep messing with antique watches.

Need to find out the drill size, but if £10 set if taps and an couple of hours with a bit of steel and a file will sort it, that night be my best option.

[graemeW]

If i end up making one of these, what do I need to make it from. Would it have been hardened? It doesn't really feel hardened, I can scratch at the edge with a blade.

It's not a spring piece so doesn't need to be spring steel. 

I can make it from mild, stainless, or tool steel. If I make it from tool steel, I can heat treat it if needed.

[tomh207]

42 minutes ago, graemeW said:

If i end up making one of these, what do I need to make it from. Would it have been hardened? It doesn't really feel hardened, I can scratch at the edge with a blade.

It's not a spring piece so doesn't need to be spring steel. 

I can make it from mild, stainless, or tool steel. If I make it from tool steel, I can heat treat it if needed.

Personally, and I’m no expert bear in mind, would go for the ease of working tool steel. If I had the skills I would also look at making a new setting lever screw so I could get a suitable tap and die so they match perfectly. Once the setting lever is pinned and tapped I would consider hardening and tempering both followed by a right good polish to reduce future oxidation.

hopefully a real expert will come along and say I have the right idea or shoot me down in flames so we can both learn something.

 

Tom

[graemeW]

4 minutes ago, tomh207 said:

Personally, and I’m no expert bear in mind, would go for the ease of working tool steel. If I had the skills I would also look at making a new setting lever screw so I could get a suitable tap and die so they match perfectly. Once the setting lever is pinned and tapped I would consider hardening and tempering both followed by a right good polish to reduce future oxidation.

hopefully a real expert will come along and say I have the right idea or shoot me down in flames so we can both learn something.

 

Tom

I'll probably get a tap and die set in 0.8, then if the screw doesn't fit nice, I can make one of those too.

I'll see what steel I have lying about. I know I have a sheet of ground tool steel, but I think it's about 3mm thick. Could still use it, will just be more work. If not ill find something hardened and soften it up again.

[Neverenoughwatches]

Won't hurt to try this...depends how hard the setting lever is and what screws you have....anneal the part....go up a size in screw thread. An old machinist trick for making a tap out of a screw...is to cut two slots down the its length...not sure what you are going to use on something this small.

[graemeW]

37 minutes ago, Neverenoughwatches said:

Won't hurt to try this...depends how hard the setting lever is and what screws you have....anneal the part....go up a size in screw thread. An old machinist trick for making a tap out of a screw...is to cut two slots down the its length...not sure what you are going to use on something this small.

Only problem with that is it would mean drilling out the main plate and the barrel bridge to take the bigger screw, which I'd probably have to make anyway.

[AndyGSi]

I'd just use a 0.8 tap on the existing hole and get a lot of assorted screws.

[graemeW]

13 minutes ago, AndyGSi said:

I'd just use a 0.8 tap on the existing hole and get a lot of assorted screws.

The hole is already too big for a 0.8mm screw. And the screw in question is the one that's sandwiched between the main plate and the barrel bridge, with the head flush with the top of the bridge. It's not a normal screw (it's a normal setting lever screw though).

So I have no choice really other than to use this screw. The hole in the setting lever is already big enough to just slide up and down the screw. I could try and close the hole up, but there isn't much metal there to squish back in.

[Mercurial]

It isn’t a proper repair, but one way of getting a watch screw to bite in a stripped hole is to insert a very fine piece of copper or brass wire, to fill the hole slightly and then the screw should bite. The technique has the advantage of being reversible, so you can perform a more robust repair in the future.

When there isn’t much metal to plug or bush a hole for a screw,  you can open out the hole from the inside with a tapered reamer, with the larger end on the inside.

That way, when the plug is drilled and tapped, the screw will pull the plug deeper against the taper.

If this is carefully done, nothing would show on the upper surface.

It is difficult to judge whether there is enough metal thickness for this technique to work in this instance, but it’s worth considering. 

You could also silver solder the plug in place if you have access to a fine enough torch, that will apply sufficient heat to the small area where you need it. 

I hope this helps,

Mark

[Neverenoughwatches]

6 hours ago, graemeW said:

Only problem with that is it would mean drilling out the main plate and the barrel bridge to take the bigger screw, which I'd probably have to make anyway.

Thats fair enough if you dont want to modify the movement, but you only need to widen the hole in the plate, for the bridge...the screw head can be reduced. So that just leaves the option of plugging the hole in order to re-machine a new thread or make a complete new setting lever.

Or source another.

[nevenbekriev]

This is going to be a long one...

First, You don't need to close the hole with domed punch, as this is a hole in narrow strip. There is no enough 'meat' on both sides near the hole, so this thin places will elongate, and the thinner one will elongate more thus bending the part.

Buying tap and die and making the part is good point, but in this modern world the tools are made to sell them, but it is not sure that they will be able to do the job. My attempts to buy new dies once ended with conclusion that one has to make taps and dies by himself.

Now, the watcmaker's die not always look like the normal ones. Often dies are used that are just like a nut made of hard steel. They don't have holes around with cutting edges formed. Actually, making thread there is not by cutting, but rather by moving metal. The rod that You need to make thread on is to be soft as possible and with a little smaller diameter than the thread. So if You need 0.8 thread, then use 0.75 rod.

I will try to explain what to do and thus shorten the whole 'theory', then if needed, will explain more about what is needed.

You get new stem with long piece of thread 0.9. May be several stems, as some may break in experiments. No mater what, just the thread part is needed. Then You harden the thread part and temper it just to 170 degr (just to beginning of appearance of slight srtaw color) to reduce it being so brittle, but keep it as hard as possible. Then You form by grinding a tap out of it. Will show pictures at the end. Then You use the tap to carefully cut new thread in the setting lever hole. Apply oil. If it doesn't cut, then anneal the lever, if needed resharpen the tap. You must cut good well looking thread. When done, You harden the lever and temper it to blue.

Now You need to make a die. You need a flat piece (about 1mm) of soft tool steel. Drill a 0.8 hole, then cut thread in it with the tap. Then You make small champfer on one side like funnel, the other side grind flat, then repeat the thread with the tap to be sure it is clean. Harden the die the same manner as the tap.

Now, You have to make new setting lever screw. The material needed is tool steel rod, soft (annealed) state.

On the lathe, You begin with the threaded part. You turn cylindrical part with 0.85 diam, then form the thread by the die.  Start with the champfered side. Use oil, go ahead slowly by forward-back rotations of the spindle by hand. If it doesn't want to go easy, then the rod is thick. Then it will break in the die and You will have to make new one. If the rod is thinner than needed, the thread will not be full sized. When the thread is ready and looks fine, turn the other side of the die and finish the thread to the end (to the shoulder).

Then continue turning the screw, when ready, cut the slot with thin jeweler's saw. Harden the screw, then temper it to blue. Then You can polish the screw or at least the head that is seen on back side of the movement

Of course, if You lathe can cut threads, You can make the tap needed and make new lever keeping the existing screw, but making the lever is for me the longer way

Edited January 27 by nevenbekriev