How to install crystal in beveled bezel?

[jplotkin]

Hi All:

I finally overhauled this this family heirloom -- Helbros triple date -- to working order. But it's missing its crystal.

I can make measurements and order some (plastic) replacements -- but how will I install the crystal on this watch? Because the bezel in which the crystal is seated is bevelled. Do I need to somehow distort/bend the crystal while installing it inside this beveled edge?

Also, do I need to measure the height of the hands to determine the appropriate curvature of a replacement crystal?

Thanks for advice.

 

[roughbarked]

Otherwise you may use one of the presses designed to stress the plexi to fit.

 

[karlmansson]

I've never had much luck using the crystal lifting tools. Usually there are visible markings left behind along the periphery or i just shear the crystal right long the rim, especially on armored crystals. I always use a crystal press instead. A domed, concanve die piece that allow the rim of the crystal to rest on the die and then a smaller concave one that will fit through the front of the watch case. I use plastic film to protect the crystal but then it's just a matter of compressing the cystal som that the rim contracts ever so slightly, fit the bezel of the case over it and release the lever or the screw. I use a Robur style press with a screw actuated piston but the cheap presses on ebay with dies work in a pinch. They won't do for waterproof, armored crystals that press straight in though. There you need something more rigid.

 

[Jerry Kieffer]

Hi All:

I finally overhauled this this family heirloom -- Helbros triple date -- to working order. But it's missing its crystal.

I can make measurements and order some (plastic) replacements -- but how will I install the crystal on this watch? Because the bezel in which the crystal is seated is bevelled. Do I need to somehow distort/bend the crystal while installing it inside this beveled edge?

Also, do I need to measure the height of the hands to determine the appropriate curvature of a replacement crystal?

Thanks for advice.

View attachment 683587

View attachment 683588 View attachment 683589

While others have suggested methods of crystal installation, your case, may or may not except a crystal because of the beveled seat.

If not,I have a lathe setup that allows me to machine crystals as required, but is currently packed for demonstration purposes as I am leaving in the morning to do a watch class.

If interested, I can post photos when I return next week.

Jerry Kieffer

 

[jplotkin]

Thank you all.

Interested to see the lathe setup when convenient, Jerry.

 

[karlmansson]

While others have suggested methods of crystal installation, your case, may or may not except a crystal because of the beveled seat.

If not,I have a lathe setup that allows me to machine crystals as required, but is currently packed for demonstration purposes as I am leaving in the morning to do a watch class.

If interested, I can post photos when I return next week.

Jerry Kieffer

I don't get it Jerry, that's a standard seat for an acrylic crystal. The bevel is how the crystal is held in place from its own tension. The comressible crystals are made to fit that exact shape and you order them to size in increments of 0.2mm. Not sure why you would need to machine them.

 

[Jerry Kieffer]

I don't get it Jerry, that's a standard seat for an acrylic crystal. The bevel is how the crystal is held in place from its own tension. The comressible crystals are made to fit that exact shape and you order them to size in increments of 0.2mm. Not sure why you would need to machine them.

Karl
Assuming that I understand the OP`s explanation, the bottom seat the crystal rests on is not parallel with the dial, but angles upward. If so, it may not allow a standard crystal to seat deep enough to catch the outer edge of the case unless shaped to do so.
If not, then you are correct and no modification is required.

Jerry Kieffer

 

[karlmansson]

Karl
Assuming that I understand the OP`s explanation, the bottom seat the crystal rests on is not parallel with the dial, but angles upward. If so, it may not allow a standard crystal to seat deep enough to catch the outer edge of the case unless shaped to do so.
If not, then you are correct and no modification is required.

Jerry Kieffer

I see. I interpreted the question as having the bevel on the ID of the bezel as he was referring to getting it "inside the beveled edge". I may have been mistaken.

 

[DeweyC]

I see. I interpreted the question as having the bevel on the ID of the bezel as he was referring to getting it "inside the beveled edge". I may have been mistaken.

Karl,

I also saw no reason to drag out a lathe. There is seldom a good reson for modifying the bezel seat. And crytals are one of the few things that are plentiful so it is more expedient that to order one thena to modify one. So I too was confused.

FWIW, here is my goto for plastic crystals. It is basically a visegrip that takes standardized dies to fit a wide range of crystals. Also like you, I never was successful with the "claw". I also sheared a number of WT crystals.

You often see these incomplete (just the visegrip and maybe one die). But as you can see, the dies are easy enough to make if you are indeed fortunate enough to have a lathe.

But perhaps another question is was that crystal originally plastic or glass?

 

[gmorse]

Hi John,

A domed, concave die piece that allows the rim of the crystal to rest on the die and then a smaller concave convex one that will fit through the front of the watch case.

This is what Karl was talking about in post #3.



Regards,

Graham

 

[karlmansson]

Karl,

I also saw no reason to drag out a lathe. There is seldom a good reson for modifying the bezel seat. And crytals are one of the few things that are plentiful so it is more expedient that to order one thena to modify one. So I too was confused.

FWIW, here is my goto for plastic crystals. It is basically a visegrip that takes standardized dies to fit a wide range of crystals. Also like you, I never was successful with the "claw". I also sheared a number of WT crystals.

You often see these incomplete (just the visegrip and maybe one die). But as you can see, the dies are easy enough to make if you are indeed fortunate enough to have a lathe.

But perhaps another question is was that crystal originally plastic or glass?


View attachment 683711


View attachment 683713 View attachment 683712

Good point about glass or acrylic. Acrylic can be compressed but you will have a very bad time trying to compress glass... For some older pocket watches where the owner wishes to keep an original mineral, domed crystal the bezel can be heated on a hot plate after having been removed from the case proper.

 

[karlmansson]

Hi John,


This is what Karl was talking about in post #3.

View attachment 683722

Regards,

Graham

Thank you for clarifying Graham! What isn’t apparent from the picture though is that the upper die needs to be concave for the compression to work.

 

[roughbarked]

Yes these combinations of convex/concave dies, distort the plexi to fit it in the bevelled edge.

 

[karlmansson]

This is my weapon of choice. I had no case handy so I hope my rough casting will convey the principle.

I also keep a few flat nylon dies for closing stubborn flat backed snap cases.

 

[jplotkin]

I see. I interpreted the question as having the bevel on the ID of the bezel as he was referring to getting it "inside the beveled edge". I may have been mistaken.

Your interpretation of my query is correct, Karl.

The tool sets in this thread make me jealous of you non-amateurs. Thanks again.

 

[karlmansson]

Your interpretation of my query is correct, Karl.

The tool sets in this thread make me jealous of you non-amateurs. Thanks again.

I'm very much an amateur. I've just had more time to fall down this rabbit hole than you have .

 

[Dave Haynes]

The crystal pinching tools work fine if used on crystals that are made for it. I almost never mar a crystal after use. If you try it on an a thicker crystal all bets are off, then a press of some kind is the weapon of choice.
By the way if you are buying a pinching tool, they come in two sizes, you will never use the small one and always use the large one. And make sure they have the flat platform with it. It is essential.

 

[Dave Haynes]

remove

 

[Jerry Kieffer]

Karl,

I also saw no reason to drag out a lathe. There is seldom a good reson for modifying the bezel seat.


View attachment 683711


View attachment 683713 View attachment 683712

Thank you all.

Interested to see the lathe setup when convenient, Jerry.

Per your request.

Just to clarify, your statement that "the Bezel in witch the crystal is seated is Beveled" suggested that the bezel base may be shaped per the attached sketch. While certainly not common, I do have a Vacheron and a Patek in my collection with a similar crystal pocket arrangement.
If crystal fitting modifications are required, my method of fitting is as follows.

(1) The first photo shows a WW pot collet with thin rubber mounted on the face of the collet. The other short work piece is the same diameter and also has thin rubber mounted and is center spot drilled.

(2) Second photo shows the two parts installed on the lathe with a crystal installed between the two with light tension. The rear short piece is supported by a live center in the tailstock. The lathe tool installed has a small ball bearing on the tip. This is used by slowly advancing it up to the crystal while it is slowly rotating. Once making contact, advancement is continued until no visible runout can be be observed under loupe magnification. Additional light tension is now added by the tailstock hand wheel to lock the crystal in place. Usually takes about 30 seconds.
Also the ball bearing tool was not made for this application since it has had a million other applications over the years.

(3) For modifications the crystal can be made of any material such as plastic, glass or whatever. Plastic can be machined using standard lathe tools. Glass or other hard crystal material can be ground from any angle including OD. For this I mount a micro pneumatic die grinder on the tool post per the third photo.
These tools are also used in dental labs and other applications and can operate up to 300,000 rpm producing a fine clean surface with abrasive stones as shown. While normally not required, the ground surface can be polishing in a conventional manner or flame polished in a few seconds as it is rotated in the lathe. In addition, the case or bezel can be slipped over the tailstock ram for test fitting before removing the crystal from the setup per third photo.

Jerry Kieffer