Drilling a hole Rolex 5517

[NCRich 13,748]

So I've got a JK 5517 and I want to install fixed bars.  I'm no stranger to drilling these lugs, but I'm not quite sure of the size bit.  I have some 2mm stainless rods and I would prefer a press fit.  I'm not sure what size to drill the receiving holes.  2mm? 2.1mm? 

I think I could drill a 2mm hole then put the rod in the freezer and the case in the oven.  Contraction and expansion would take place respectively and I could just insert the rod and wait for it to come to room temp.  Then it would be snugged down.

Anyone have any thoughts?  Some on you pretengineers have any knowledge in this area?

Thanks in advance.

[als86 5,278]

Without going into too much detail I think that would work but it would be quite tight.

316SS(Or austenitic)  has an expansion rate of 1.34mm/mm but if you exaggerate the upper and lower temps (so 300°C is nearly 5mm/m) i.e 280°C and -5°C it should make the tolerances bigger and 0.1mm should be suffice. So 2 mm bit.

Thats my thoughts from an engineering background    
 

Note: I have zero expertise in modding watches this is purely the physics of it.

[NCRich 13,748]

13 minutes ago, als86 said:

Without going into too much detail I think that would work but it would be quite tight.

316SS(Or austenitic)  has an expansion rate of 1.34mm/mm but if you exaggerate the upper and lower temps (so 300°C is nearly 5mm/m) i.e 280°C and -5°C it should make the tolerances bigger and 0.1mm should be suffice. So 2 mm bit.

Thats my thoughts from an engineering background    
 

Note: I have zero expertise in modding watches this is purely the physics of it.

Thanks mate!  Of course this will assume I can drill the hole straight (even with a drill press).  I think I'll go with a 2mm bit and I can always size up to a 2.1 if need be.

[FudgyDocker 3,500]

I know you're old and getting a bit funny, so I'll just say "Wear an oven glove when taking the case out of the oven"

You're welcome. You'll thank me for this sage advice, later.

[Dr Fun Socks 76]

Id start small, obviously it’s easier to make a hole bigger than smaller. Maybe start with a 1.8 or 1.9mm drill bit and check to see if it slides in. Im sure you can get pins with knurling on one end so it grips when you push it in. Or just hit one end of you 2mm bar with a hammer to slightly ovalise it so it grips. Id say you have close to no chance or cryo fitting it in but i like the thought process. For what its worth im a tool maker but obviously just use whatever method your most happy with!

[vmlopes 1]

Just get a 2mm reamer and stop guessing

[deju 1,874]

When undertaking any project, always start by thinking what would @Popperini do. This is the perfect process of eliminatio . Now you know the wrong answers, your left with the correct way

[Popperini 17,842]

9 minutes ago, deju said:

When undertaking any project, always start by thinking what would @Popperini do. This is the perfect process of eliminatio . Now you know the wrong answers, your left with the correct way

That's really quite hurtful.

True, but hurtful.

[NCRich 13,748]

1 hour ago, Popperini said:

That's really quite hurtful.

True, but hurtful.

3 hours ago, vmlopes said:

Just get a 2mm reamer and stop guessing

Hmm..reaming.........what is the advantage of that over a drill bit in this application.  I looked it up online but I'm not sure why it would be better.

[narikaa 129]

A far simpler 'quick and easy' transformation is masking the existing spring bars with a tube.

When reaffixed you have the appearance of a solid bar

 

 

 

 

Edited June 15, 2022 by narikaa

[Popperini 17,842]

BTW, I'm genuinely interested to hear how this one goes, as I've also got a length of 2mm stainless rod I bought with exactly the same project in mind.

I was going to drill the lug holes out to 2mm - knowing that my abilities are so woeful that the holes would almost definitely end up a bit over-size anyway... Then use some JBWeld to hold the bars in.

An interference fit (hot/cold as you described Rich) would be the ideal method. 

[Foxindebox 464]

11 minutes ago, Popperini said:

BTW, I'm genuinely interested to hear how this one goes, as I've also got a length of 2mm stainless rod I bought with exactly the same project in mind.

I was going to drill the lug holes out to 2mm - knowing that my abilities are so woeful that the holes would almost definitely end up a bit over-size anyway... Then use some JBWeld to hold the bars in.

An interference fit (hot/cold as you described Rich) would be the ideal method. 

If you are planning to refinish the sides of the case afterward (Which I assume you would to clean up the ends of the rods), you can drop a bit of solder into the gaps (if any…).

[vmlopes 1]

2 hours ago, NCRich said:

Hmm..reaming.........what is the advantage of that over a drill bit in this application.  I looked it up online but I'm not sure why it would be better.

Because it will be way more accurate and less chance of wondering

[NCRich 13,748]

20 hours ago, vmlopes said:

Because it will be way more accurate and less chance of wondering

I'm still not sure I understand.  I have a pilot hole already there in the case, all I have to do is enlarge it with progressively larger drill bits.  I've done it a lot before and never had an issue with wandering.  I can see this if no hole existed, but one does as a guide.

[Popperini 17,842]

2 minutes ago, NCRich said:

I'm still not sure I understand.  I have a pilot hole already there in the case, all I have to do is enlarge it with progressively larger drill bits.  I've done it a lot before and never had an issue with wandering.  I can see this if no hole existed, but one does as a guide.

I don't think vmlopes realised that the lugs are already drilled. As you say - there's bugger-all chance of any wandering happening when you're drilling through existing holes.

Unless you're me, of course.

[NCRich 13,748]

9 minutes ago, Popperini said:

I don't think vmlopes realised that the lugs are already drilled. As you say - there's bugger-all chance of any wandering happening when you're drilling through existing holes.

Unless you're me, of course.

Well I've got to wait for all the parts to come in, so lots of time to ponder before destruction.  I think it will be 2.1mm in the end with a tiny bit of solder to finish it off.  Maybe some JB weld.  Have to see.