Mid case and case back restoration and re threading

[Roll1ex]

I have taken up this rather odd endeavor of re threading the case-back and mid-case of my 1960’s Rolex.

This is not a well-documented topic so I will be posting more information and updates as I go along.

• Rolex threads are 60-degree metric profile with 0.5mm pitch.
• Since both parts are being re threaded, as long as the pair is threaded correctly it will work. (Metric or imperial)
• There is a lot of thread cutting theory required which will be discussed later.  A threading calculator will be helpful then.

There is one documented repair like this HERE. Pictures are quite helpful.

Since I am  doing it for the first time, this is also a call for help with questions in the end.

The parts with pitting:

Both mid case and case back has 4-5 patches of varying sizes like these. (steel after the seam is the opening tool and not to be confused with an additional step)

Pitting runs deep even after filing off the threads.

 

 

 

Pictures of thread dimensions: Consider the fact that both threads are worn and damaged from multiple places so these are approximate.

Questions and help:

For deep pitting, the plan is to get diamond burrs and remove material and fill since that is the only way to get rid of pitting, better ideas appreciated.

There is some talk on Rolexforums about 304 Steel in 60’s should I be getting that welded since my piece is from that era? https://www.rolexforums.com/showthread.php?t=643301

Any laser welders out there who have practical experience of using different shielding gases and materials please hit me up.

Suggestions appreciated.

Thank you!

Edited February 19 by Roll1ex
Added pictures, Changed formatting

[caseback]

Can't help you with the laser welding, only a practical tip for the threading: when threading, reverse the rotation of the lathe and flip over your cutting tool. That way you are cutting while moving out, so there is no risk of crashing into your part. Joe Pie has a video on youtube explaing that.

[Neverenoughwatches]

Maybe I'm missing something here, but how are the threads going to mate since the caseback threads diameter have been reduced and the case threads diameter will be increased ? 

Are the threads not further apart ?

Are we just not looking at a big screw,  once threads are worn you need a bigger screw ?

[RichardHarris123]

I think the idea is to weld some extra material on and then thread. 

[Neverenoughwatches]

5 minutes ago, RichardHarris123 said:

I think the idea is to weld some extra material on and then thread. 

I get that Richard but it looked like a lot if not all of the thead had been removed from the caseback, was maybe just the picture made it look that way.

[AndyGSi]

5 minutes ago, RichardHarris123 said:

I think the idea is to weld some extra material on and then thread. 

I think that's their idea but it's a hell of a lot of laser welding before you even look at finishing and then tapping.

Would have been easier just to refill the existing thread where missing.

[Neverenoughwatches]

8 hours ago, Roll1ex said:

For deep pitting, the plan is to get diamond burrs and remove material and fill since that is the only way to get rid of pitting, better ideas appreciated.

Ah-ha thats gonna be some clever repair .

[AndyGSi]

2 minutes ago, Neverenoughwatches said:

I get that Richard but it looked like a lot if not all of the thead had been removed from the caseback, was maybe just the picture made it look that way.

Yes I think they've made the mistake of removing the complete thread with the intention of starting again. 

[Roll1ex]

5 hours ago, caseback said:

when threading, reverse the rotation of the lathe and flip over your cutting tool. That way you are cutting while moving out, so there is no risk of crashing into your part. Joe Pie has a video on youtube explaing that.

Thank you for the response.

I have that in mind however doing that with the case back will be challenging since a tool that small has to be made.

https://www.laboratorioportanova.eu/en/restorations/lavori-su-casse/rolex-submariner-case-thread-reset/

This guy has made a case back holder to thread inward which gives relief and some space to disengage the lead screw.

threading outward will be done for the mid case.

 

2 hours ago, RichardHarris123 said:

I think the idea is to weld some extra material on and then thread.

Exactly, add material on both parts (about 0.4-0.5mm ) and re thread the pair. (Since depth of thread is about 0.3 and I have stripped a bit more than the full thread off.

 

2 hours ago, AndyGSi said:

Would have been easier just to refill the existing thread where missing.

I considered that. but more than half of the case back threads were damaged.

Also pitting is like a slow chain reaction, and will continue to spread slowly till the entire area in not filed or sanded out. Just laser welding is irresponsible. Ideally a drill and fill operation has to be done like cavities. 

 

Even after stripping the threads and filing down more material, pitting is present below, so this had to be done. What is more concerning is the inner side corresponding that area has pitting, which makes me suspect that it has bored a hole in the metal. @Neverenoughwatches I guess we will find out soon if the burs land up on the other side LOL.

 

All this being said, there is a backup plan: make pair of threaded rings and weld them on.

[AndyGSi]

50 minutes ago, Roll1ex said:

I considered that. but more than half of the case back threads were damaged.

Have you looked into laser welding and what a slow process it is?

[praezis]

I suspect we will never see the finished project here, it will disappear in silence.

Would be very happy if I am wrong!

Frank

[Roll1ex]

1 hour ago, AndyGSi said:

Have you looked into laser welding and what a slow process it is?

Yes probably 2-4 hours and since laser welding on these parts is done using a 0.2-0.3mm wire it will be 2 passes with some sanding in the middle.

[Neverenoughwatches]

15 minutes ago, praezis said:

I suspect we will never see the finished project here, it will disappear in silence.

good choice of words Frank, I've had more than one such project lol. 

[AndyGSi]

20 minutes ago, Roll1ex said:

Yes probably 2-4 hours and since laser welding on these parts is done using a 0.2-0.3mm wire it will be 2 passes with some sanding in the middle.

So you're expecting to be able to laser weld a bead 0.2-0.3mm all the way round and then repeat?

All I can say is good luck with that.

[Roll1ex]

@AndyGSi

I have done intense filling in the past with lugs.

Case back is finer job and might take more passes.

***

The quality of the weld and stress introduction in the work piece remains the prime concern since I will be threading on the weld.

Desperately looking for someone with experience in laser welding with Nitrogen/argon/C25 since I could use their knowledge and experience.

[SwissSeiko]

I do PUC welding on cases. For this much repair, you will want 100% argon. I don't use it when filling in dents and gashes, but it will leave a bit of soot, and you'll want this to go as smoothly as possible. My suggestion for this repair, and how I would do it:

Turn down some 304l round stock to 0.2mm larger OD of the finished thread. Then bore out the center to slip over the case where the threads were. Then seam weld on the top and bottom points. Then chuck it in the lathe and clean up the welds. Then I would cut the threads, but turning the headstock by hand. Do this process for both the case back and the case. Once the threads are cut, you'll want to file them down to the correct OD, as single point threading tends to make very sharp and weak major diameters. 

[Roll1ex]

@SwissSeiko

Have you tried nitrogen welding? I am planning to use nitrogen based on the two research papers I am attaching since the evidence seems compelling.

 

 

2 hours ago, SwissSeiko said:

Then seam weld on the top and bottom points.

Refer to my inner and outer side picture: If I am seam welding the bored ring, it will be to the bottom part of the outer side and the top part of the inner side.

Once I cut the starting relief for threading it will kill the bottom weld rendering the weld useless.

Or am I missing something?

What are your opinions about welding a threaded ring pair to the mid case and back?

Welding porosity .pdf Keyhole induced porosity.pdf

[RichardHarris123]

Could the idea by @SwissSeiko be improved by heat fitting the inset and welding the top only? I haven't done anything like this, so it may be a terrible idea.

[AndyGSi]

26 minutes ago, Roll1ex said:

@SwissSeiko

Have you tried nitrogen welding? I am planning to use nitrogen based on the two research papers I am attaching since the evidence seems compelling.

 

 

Refer to my inner and outer side picture: If I am seam welding the bored ring, it will be to the bottom part of the outer side and the top part of the inner side.

Once I cut the starting relief for threading it will kill the bottom weld rendering the weld useless.

Or am I missing something?

What are your opinions about welding a threaded ring pair to the mid case and back?

Welding porosity .pdf 972.82 kB · 0 downloads Keyhole induced porosity.pdf 1.85 MB · 0 downloads

What equipment are you intending to use as these research papers appear to be heavy duty industrial welding?

[Roll1ex]

30 minutes ago, AndyGSi said:

What equipment are you intending to use as these research papers appear to be heavy duty industrial welding?

Smaller laser welding machines intended for jewellery.

In the past I have given pieces to shops that take job work and weld without shielding gas. In that porosity issues and bubble formation has been observed.

Pure nitrogen also makes for a flatter weld by breaking surface tension as compared to ambient or Argon. I have observed first hand in other smaller job work done by these shops.

[Neverenoughwatches]

Sounds like a complicated process with the potential of destroying a case, caseback or both. I'm actually pleased i understand little of the process so i dont have to get my head around it.

[Roll1ex]

51 minutes ago, RichardHarris123 said:

Could the idea by @SwissSeiko be improved by heat fitting the inset and welding the top only? I haven't done anything like this, so it may be a terrible idea.

Have not explored it since I have heard all types of warping and cracking, tempering and annealing issues with different temperatures etc.

However it's worthhy of an attempt if I go the threaded ring route since I will only be heating the ring I can always change the ring if something goes wrong.

@Neverenoughwatches

A complete new case was quite cheap even after the lug building. Pictures of which I have posted.

This is being done in academic pursuit and since I want to learn casemaking and lathe work not just movement work.

My watchmaker has offered to weld a new ring pair and says he can pull it off easily so there is that fall back plan if I fail in this initial plan.

7 hours ago, praezis said:

I suspect we will never see the finished project here, it will disappear in silence.

Since I am going to Watchmakers and job shops to use their equipment it might be slow but there will surely be an update.

[Knebo]

2 hours ago, Neverenoughwatches said:

Sounds like a complicated process with the potential of destroying a case, caseback or both. I'm actually pleased i understand little of the process so i dont have to get my head around it.

Yea, I'm also watching in wonder. Good luck @Roll1ex! 

2 hours ago, Roll1ex said:

This is being done in academic pursuit and since I want to learn casemaking a

You have my admiration and I'm rooting for you. "Who doesn't dare, can't win" 

[Neverenoughwatches]

9 minutes ago, Knebo said:

Yea, I'm also watching in wonder. Good luck @Roll1ex! 

You have my admiration and I'm rooting for you. "Who doesn't dare, can't win" 

I don't dare cross my missus, I know I wouldn't win

[Knebo]

4 minutes ago, Neverenoughwatches said:

I don't dare cross my missus, I know I wouldn't win

Yea, the missus'es are made of radium-infused grade 5 titanium. No messing with them!