Change hesalite crystal for sapphire

ig1977 · May 4, 2016

Hi there,
Is it technically possible to exchange the hesalite crystal of the Speedmaster ref 3594.50.00 for a sapphire crystal, as the one used in the Speedmaster ref. 3551.50.00?
In case it is possible, where could I get this sapphire crystal?
Thank you!

Archer · May 4, 2016

No. Diameter of the acrylic crystal is 34.13 mm, and the sapphire is bigger at 34.2 mm, so it would not fit in the case. To install the sapphire you would also need room for a crystal gasket, so the opening in the case would have to be even bigger still...

hkrauss · May 5, 2016

It's always fun to learn about different tastes. In my case, it's the other way round: I would replace all the sapphires in my Speedies with hesalite, if it were possible. An endless theme ...

relaxer7 · May 5, 2016

sapphires for me!

spen936 · Jun 12, 2016

Archer
No. Diameter of the acrylic crystal is 34.13 mm, and the sapphire is bigger at 34.2 mm, so it would not fit in the case. To install the sapphire you would also need room for a crystal gasket, so the opening in the case would have to be even bigger still...[/QUO

Archer
No. Diameter of the acrylic crystal is 34.13 mm, and the sapphire is bigger at 34.2 mm, so it would not fit in the case. To install the sapphire you would also need room for a crystal gasket, so the opening in the case would have to be even bigger still...

I've replaced a couple of Hesalite crystals with sapphire crystals for friends. Two points need to be made here: 1) obviously, your Omega warranty will be voided and 2) it requires special workholding and know-how.

The Hesalite crystal has a friction fit to the case but the sapphire crystal requires a gasket. I made a special internal gripping collet chuck for my watchmaker lathe to hold the case without scratching. A fairly hard tool is required to prevent workhardening of the case.

In both cases, the modification worked very well and passed pressure test. Basically, I made the 145.0022 case into a 3573.50.00. It's not cheap; the Omega sapphire crystal and gasket cost about $550.

Let me know if you're interested. I can give you details on the workholding, machining and correct diameter for the gasket.

Archer · Jun 12, 2016

spen936
I've replaced a couple of Hesalite crystals with sapphire crystals for friends. Two points need to be made here: 1) obviously, your Omega warranty will be voided and 2) it requires special workholding and know-how.

The Hesalite crystal has a friction fit to the case but the sapphire crystal requires a gasket. I made a special internal gripping collet chuck for my watchmaker lathe to hold the case without scratching. A fairly hard tool is required to prevent workhardening of the case.

In both cases, the medication worked very well and passed pressure test. Basically, I made the 145.0022 case into a 3573.50.00. It's not cheap; the Omega sapphire crystal and gasket cost about $550.

Let me know if you're interested. I can give you details on the workholding, machining and correct diameter for the gasket.

I think the question being asked in all these threads on forums that you have now responded to is if the sapphire crystal is a direct replacement for the acrylic crystal, and as I've noted it's not.

Of course the case could be modified to make it work, but I doubt too many people are going to want to do this. Opening up the hole in the case is not a difficult task for anyone with even a small bit of machining experience, but it's a permanent modification...

cwindham · Jun 12, 2016

I think I would stick with the hesalite crystal. If it means having to modify the case(machine it ) then it's not worth it IMO.

Taddyangle · Jun 12, 2016

I would have kept my Speediorite if I could have changed the sapphire to hesalite. Now prices so out of control with these moon watches I think I am done with speedmasters.

Archer · Jun 12, 2016

Taddyangle
I would have kept my Speediorite if I could have changed the sapphire to hesalite. Now prices so out of control with these moon watches I think I am done with speedmasters.

Little more difficult to shrink the case to make an acrylic crystal fit a sapphire case...

spen936 · Jun 12, 2016

Archer
I think the question being asked in all these threads on forums that you have now responded to is if the sapphire crystal is a direct replacement for the acrylic crystal, and as I've noted it's not.

Of course the case could be modified to make it work, but I doubt too many people are going to want to do this. Opening up the hole in the case is not a difficult task for anyone with even a small bit of machining experience, but it's a permanent modification...

I understood the original question but frankly, your response was incomplete. My post more fully answers the question. A sapphire crystal can be used but the case needs to be modified. You never know, this may be interesting for some.

Regarding the machining, you're right; it's pretty straight forward. The real trick is holding the case without marking it. Also, you'll want to hold it with less than 0.002" run-out. My ID collet chuck is pretty ingenious and does the job perfectly. Regarding the know-how that I mentioned, one performing this mod needs to know the correct diameter for the counter-bore in the case. Too small and you'll never get the sapphire crystal to seat; without damaging the gasket. Too large and you'll never get the pressure test to pass.

The main purpose of my response was simple. Knowledge is power my friend.

Spacefruit · Jun 13, 2016

Actually, and here I must be pedantic, the op asked if the crystals can be exchanged.

They cannot, as @Archer says. The case can be modified, as @spen936 points out - a magnificent piece of work by the way - but truly a waste of time and money apart from the satisfaction of having done it. Again I respect that. But to me that is like modifying the lugs to take a 21mm bracelet.

However I saw the op question as asking if he could flip one out and shove the other in, like changing a dial for a racing dial. A simple swap.

This question has come up numerous times, asking both ways. While it is always amusing to me to hear the answers and discuss the issue, the reality is that if you don't like a sapphire, or a hessalite, for goodness sake go and buy the other watch.

Unless you want to face the engineering challenge for its own rewards. That will cost a lot of money, and devalue your watch, and leave you with a watch that not many people will ever want to own after you.

Archer · Jun 13, 2016

spen936
The main purpose of my response was simple. Knowledge is power my friend.

Sure - that's why you dug up a 7 year old thread on WUS to post the same information...just for spreading knowledge...I admire your dedication. 😀

Figuring out what size to bore the hole is not so mysterious - I've done it before when designing case back modifications to fit sapphire crystals:

But if I really wanted to figure this particular modification on a Speedmaster out the answer is pretty simple - take the Speedmaster I have in the shop right now for service that has a sapphire crystal in it, press it out, remove the gasket, and measure the case opening...not a ton of know-how involved in that. 😁

Thanks for passing this along, but I don't think too many people are looking to do this modification.

Cheers, Al

spen936 · Jun 13, 2016

Spacefruit
Actually, and here I must be pedantic, the op asked if the crystals can be exchanged.

They cannot, as @Archer says. The case can be modified, as @spen936 points out - a magnificent piece of work by the way - but truly a waste of time and money apart from the satisfaction of having done it. Again I respect that. But to me that is like modifying the lugs to take a 21mm bracelet.

However I saw the op question as asking if he could flip one out and shove the other in, like changing a dial for a racing dial. A simple swap.

This question has come up numerous times, asking both ways. While it is always amusing to me to hear the answers and discuss the issue, the reality is that if you don't like a sapphire, or a hessalite, for goodness sake go and buy the other watch.

Unless you want to face the engineering challenge for its own rewards. That will cost a lot of money, and devalue your watch, and leave you with a watch that not many people will ever want to own after you.

Spot on! I'm not advocating the mod. The two that I've done were for friends. Both are serious collectors and fully understood the ramifications.

ricardorio · Jan 4, 2022

hkrauss
It's always fun to learn about different tastes. In my case, it's the other way round: I would replace all the sapphires in my Speedies with hesalite, if it were possible. An endless theme ...

It´s that possible 😕 ? According Archer explanation, it is possible ::psy::

... hesalite require only pressure inside the case. I am rigth ?

best regards

shoota70 · Jan 5, 2022

I would do this mod to every plastic faced Speedy I've ever owned - if it was free.

Change hesalite crystal for sapphire

ig1977

Archer

hkrauss

relaxer7

spen936

Archer

cwindham

Taddyangle

Archer

spen936

Spacefruit

Archer

spen936

ricardorio

shoota70

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