Crystal Press

[offshore]

Okay- I recently acquired a large lot of crystals, and as I have a couple of el cheapo presses ( one with nylon dies, and one with brass- this is more a case back tool I think) proceeded to install some new crystals.

Measured the watch in question- ascertained that it was definetly a snap in crystal, measured and remeasured the crystal- checked the dies as the right size, and proceeded to snap the crystal in to place.

Poof.... 10,000 shards of glass over me, my bench, and worst of all inside the watch.

So clean it out- and do the same checks again- same result.

Had another crystal to replace - for one of our people here- but this one had the movement removed.

Same result- Bloody good thing I got many thousands of these crystals!!!!!

So rechecked, and found I may have been out maybe .01mm on my dia of case ( Maybe its not exactly round), also thought that maybe some lubricant may help, so ran a smear of vaseline around the outside edge of the crystal which was the next size down- success.

But I remained, and still do, sceptical of my ability to carry out ongoing crystal installs.

Read up on a few articles from NAWCC ( One attached here for info)

http://nawcc-mb.infopop.cc/groupee/forums/...61/m/7701010671

and found a discussion about heating the watch with a hair dryer- to get the case to expand to better accept the crystals. Have tried this, and am getting better- not perfect results.

I wonder if the crystals I have, which are pretty old, have to some degree gone a bit "fragile' with age??

Is this possible?

Also is it time to buy a screw type crystal press, is this cheap stuff just not up to the job?

There are a number of interesting threads on the various NAWCC forums- both watch repair, and Horological Tools, ( which I commend to those like me- still learning)

So end of experience one- Who else has had any experience with this?- any advice?

Offshore

[Logan]

I place a piece of teflon sheet (although any non-scratching sheet will do) between the die and the crystal. This helps prevent scratches especially on AR coated crystals and it also evens out the pressure over the diameter of the crystal.

[RWG Technical]

Glass or sapphire crystals are retained by a plastic compression ring. The ring is about 1mm thick, and the crystal is a bit smaller than this.

I have never had a crystal break, the only things I can think of are:

1. The crystal is too big for the hole and or the compression ring is missing... this is my first guess as per your description...

2. Your using a cheap press and the dies are bending and not putting even pressure on the crystal, is it's cocked off to one side, even a little bit, it will break. Although this is possible it seems unlikely to be the cause of your problem, I think #1 is more in line with the breakage.

For ref, I have a crystal press, and all the dies are Delrin NOT Nylon, Nylon sucks for dies as it bends under pressure and distorts, and all the cheaper presses are using Nylon...

But a good quality press with a good set of dies is $600...not cheap ...

You dont' use any lube, insert the compression ring in the case first, make sure seated correctly, put the crystal in place, use an appropriate die, support the case, and press even until seated...

Not sure if this will help or not...

RG