This type of installation requires a press that pushes down on the new crystal from the top, in a uniform way over the entire surface of the crystal. The pusher/die on the press and the watch case need to be parallel, otherwise the glass will become crooked, and you risk breaking the crystal.

Hold case over crystal, press foot pedal to compress the crystal, slip case over the crystal, release foot pedal - you are done: Assortment includes Bergeon 5500-38 (36 x 34 mm), 5500-22 (33 x 32 mm), 5500-23 (31 x 30 mm), 5500-24 (29 x 28 mm), 5500-25 (27 x 26 mm), 5500-26 (25 x 24 mm), 5500-27 (23 x 22 mm), 5500-28 (21 x 20 mm), 5500-29 (19 x 18 mm), 5500-30 (17 x 15 mm), and 5500-36 (14 x 12 mm). There are 3 main ways to fit a watch crystal. Each will require its own specialized dies used to properly install the crystal into the case. They make Acrylic crystals in 0.1mm or 0.02 increments or 1 to 2 tenths of a millimeter. Sometimes you will see them listed as a 300, 301, 295, 296 which would be translated to 30.0mm, 30.1mm, 29.5mm, 29.6mm. respectively.The internal tension ring most common on vintage diver's and diver style watches, as well as vintage watches with over 3 ATM water resistance, works by having the plastic skirt squeezed between the case wall and the internal ring. Once its been tightened down, about 0.2-0.3 mm, the crystal is set into the case bezel and released.

I also plan to put a fillet (0.25?) on some of the outer 'corners' mainly for aesthetics, and one on the entry to the seat to make it easier to get the movement in, but didn't get time to add them to my sketch, blue circles above. Insert the watch case or bezel on top the crystal and gently press down. While pressing down you move the case or bezel onto the compressed crystal until you can feel the crystal inside the grove and release.NOTE: Use extreme care in pressure fitting gold watches using a watch press because they are easily bent out of shape and damaged. A watch press can emit enormous pressure on a small surface so work carefully on any watch because the damage of bending a watch case or watch bezel is many times un-repairable. Five Types of press on crystals that we cover are: Besides the common sizes above there are some specialty brand specific crystals available from Sternkreuz. Your can find them here. On wooden stand (dimensions: 370 x 150 mm). Outfit consisting of: - 1 press No 5500. - 1 set of 9 stakes No 5500-E. - 1 set of 12 stakes No 5500-10 to No 5500-21. - 1 set of 9 stakes No 5500-22 to No 5500-30. - 1 lower stake No 5500-31. - 1 support No 5500-T28. Here is what I sketched in my lunch hour (including a doodle I did whilst on a very boring conference call) on Friday: You cannot use the same die for an armored acrylic crystal like you would for an ordinary flat or domed mineral crystal. Tension ring crystals have a high straight side so that they can be pushed straight down while slightly bending in at the same time.

Also l1 is the cutout for the stem/crown, was thinking of making it U shaped rather than square, but would model it as a square and simply fillet the corners to make it a U shape. The Set includes: 2 Reversible Delrin Dies for fitting watch bezels (40 x 45 mm and 46 x 50 mm); inner side wall depth is 4mm. The compression fit crystal is the weakest of all the crystal types as far as water resistance is concerned. To install the crystal, the skirt must be mechanically compressed to reduce the diameter by approximately .20 to .30 mm before being inserted. The crystal press die should rest on the crystal so that the bevel on the inside of the die rests on the curve between the wall of the crystal and the dome. Once I get to grips with it, I'll post the freeCAD design on thingiverse and you can also PM me for it from here 🙂Those who read this thread owe gratitude to Al for his taking the time to share his knowledge and expertise. Al's post covered the topic accurately and also corrected misinformation from some earlier posts.

In some instances, a specific type of lift or wrench can be used to remove these tension ring crystals - usually these are brand specific tools, and are not a "one size fits all" that a typical crystal lift would be. These Bergeon tapered wall dies are reversible (each piece has two different sizes, one on each side). Comes in a set of 13 pieces. For fitting certain crystal types, including tension rings. These Bergeon lower stakes dies are reversible (each piece has two different sizes, one on each side). Comes in a set of 11 pieces. For fitting certain crystal and case closing.I wasn't really aware of "front loaders", and in those cases, a crystal lift is, of course, a must. I'll get me one those for this watch and for future needs. Would you know if a crystal lift also can be just for acrylic crystals with a tension ring, or is it a bad idea? Having seen a few YouTube videos on how to use a crystal lift, it seems a very nifty tool! To install a crystal, you just install one of the dies used for armored crystals into the base. Lay the crystal on the base inside facing up. I'll stay away from the crystal press in this case. I don't want to take any chances, and after all, I'll be getting myself a crystal lift, and while waiting for it to arrive I'll service the movement and clean the other parts. One note about the crystal lifts: There are different schools of thought on whether to buy a good brand-name used lift/vise, or an inexpensive non-branded lift. I went with a Vigor that was sold as new-in-box. It ended up working well, but not until after I had to take apart the vise and replace a part. The Vigor has a rubber ring/band that applies spring-pressure to the jaws. They get old and set, and will not serve their purpose. I used an O-ring in it's place and it worked fine. These crystals are referred to by a few names, Armored, "A" type, reflector ring or tension ring, but are all the same thing. These rings are often split but the split in the ring should be closed when the ring is installed at the lower lip of the crystal. The ring must be fitted into the crystal before the crystal is pressed into the watch.