Crystal Fitting....(Challenge accepted)
Like Tree16Likes

Thread: Crystal Fitting....(Challenge accepted)

Page 1 of 3 1 2 3 LastLast
Results 1 to 10 of 23
  1. #1
    Member lysanderxiii's Avatar
    Join Date
    Oct 2006
    Location
    N 32 deg, 47' 27.9168"; W 79 deg, 54' 30.3372"
    Posts
    8,781

    Crystal Fitting....(Challenge accepted)

    Due to the lack of documentation it may be an appropriate time to consider the establishment a thread of threads for crystal fitting. Thoughts, watchmakers?
    These days there are basically three types of ways to fit a crystal. Each will require its own specialized techniques to properly install. (Removing can usually be accomplished by pressing with the thumbs on the inside…)

    1) Friction fitting


    This is the method almost all quality sapphire and mineral glasses are installed. The gasket (11) is normally a hard nylon or similar material, and can be either "L" shaped as shown or "I" shaped. The case has a slight undercut or angle cut in the vertical wall so the gasket will flow into it and lock itself in place. Simple friction between the glass and the gasket holds the glass in place. The size of the gasket is critical in the fitting of this type, it has to be the right thickness and the right diameter. To install you need a press that pushes on the outer edge of the glass or uniformly over the entire surface, and the press face and the case need to be parallel, otherwise the glass will become cocked.

    2) Tension ring fitting (r - external, l - internal)


    These two are the more common type of crystal fittings for the average diver's, or highly water tight watch, with a plastic crystal. Although, both use a "tension ring" (shown in pink) the installation methods are quite different.

    The external tension ring (most commonly seen on Rolexes with plastic crystals) is easily installed by placing the skirt of the crystal on the case so it goes around the raised wall and the tension ring is pressed on. The tension ring compresses the plastic into a good seal, and friction holds the entire assembly together. The press should only contact the metal ring.

    The internal tension ring (most common on the rest of the world's plastic crystalled diver's and diver style watches, as well as anything with over 3 ATM water resistance), works by having the plastic skirt squeezed between the case wall and the internal ring (under compression, so 'tension ring' is a misnomer). To install these you should use a press with cone shaped dies. The die wall should come in contact with the crystal at an angle so the force applied by the press both pushes the crystal down as well as tries to reduce the diameter, or roll the skirt under. This helps get the crystal skirt started in the opening in the case.

    3) Mechanical locking (r - clamped, l - wedge)


    This method is interesting as this method has the highest pressure resistance and the lowest.

    The clamped method is the most complicated method to manufacture as the clamp is a separate part and there has to be threads, or a bayonet fitting in the case. But it is the easiest to install, drop in the gasket, the crystal and clamp them together. This method along with the "L" gasket friction fitting offer the best water resistance.

    The wedge is the weakest, as far as water resistance goes, and is the only one that uses the "claw"-type crystal tool. To install the skirt must be mechanically compressed to reduce the diameter by approximately .20 to .30 mm then inserted. When the mechanical compression is relaxed the skirt's upper coned shape will force the bottom down into contact with the top surface of the case creating a seal. This is also the most commonly messed up crystal installation. Most people pick the wrong size crystal (one or two sizes too small) and the crystal does not wedge downward with much, if any force. If the crystal can be spun in the case, the crystal is too small. (Some glass in pocket watches are installed in a similar manner, although the ring is usually warmed instead of trying to compress the glass.)

    Both of these methods were/are popular with front loaders.

    4) Other less common methods (these days at any rate)

    Glue. Older square or non-round crystals are usually glued in place.

    Seiko. In keeping with doing things different, many older Seikos use mineral glass, a soft gasket and a external, snap on clamp to secure the crystal. The external clamp presses down on the glass pushing it into a soft "L" shaped gasket crerating the seal. The clamp snaps on to the case.
    Last edited by lysanderxiii; October 23rd, 2014 at 18:52.
    familiaritas parit contemptum; raritate admiratione wins.- Lucius Apuleius
    est necessry, accurate ad secundo? - Lysander magna
    iustum est horologium - Obscurus Genius

  2. #2
    Member Buzz224's Avatar
    Join Date
    Oct 2014
    Location
    N.E. central Alabama
    Posts
    897

    Re: Crystal Fitting....(Challenge accepted)

    This should be a "sticky".

    Sent from my SM-N900V using Tapatalk

  3. #3
    Member pithy's Avatar
    Join Date
    Aug 2010
    Posts
    7,080

    Re: Crystal Fitting....(Challenge accepted)

    Quote Originally Posted by Buzz224 View Post
    This should be a "sticky". Sent from my SM-N900V using Tapatalk
    Agreed but the ribs need a little more flesh on them.

    http://www.sternkreuz.de/accordion/a...alog%20G22.pdf
    Last edited by pithy; November 24th, 2014 at 19:11. Reason: add catalog link
    Buzz224 likes this.

  4. #4
    Member pithy's Avatar
    Join Date
    Aug 2010
    Posts
    7,080

    Re: Crystal Fitting....(Challenge accepted)

    Almost every day someone makes reference to pressing a plastic crystal into place and there are indeed some thick plastic crystals that are pressed into place but many round crystals are inserted. The delineation as well as the methodology for these seemed to have escaped many. The G & S drawing below illustrates the method quite eloquently. Even though previously referenced it appears to require substantial reinforcement to try to attempt eradication of another horological myth.
    Attached Images Attached Images

    bluloo and orionstars like this.

  5. #5
    Member pithy's Avatar
    Join Date
    Aug 2010
    Posts
    7,080

    Re: Crystal Fitting....(Challenge accepted)

    The international aspect of the in tension method of round plastic crystal insertion is evidenced in the Sternkreuz tool offerings - specifically the convex rubber plugs and the concave plastic dies.
    Attached Images Attached Images





    bluloo and orionstars like this.

  6. #6
    Member
    Join Date
    Apr 2009
    Location
    Canada
    Posts
    3,722

    Re: Crystal Fitting....(Challenge accepted)

    Quote Originally Posted by pithy View Post
    Almost every day someone makes reference to pressing a plastic crystal into place and there are indeed some thick plastic crystals that are pressed into place but many round crystals are inserted. The delineation as well as the methodology for these seemed to have escaped many. The G & S drawing below illustrates the method quite eloquently. Even though previously referenced it appears to require substantial reinforcement to try to attempt eradication of another horological myth.
    I agree, the G-S press is one I use often - the cabinet was worth the price just for this press IMO (didn't cost much also so that helps):





    Easy to install the PA/PHD or similar style crystals using this press, provided the case is not a front loading design. In that instance, the crystal lift or brand specific tool can be used for installation as well as removal.

    Cheers, Al
    bluloo and TheManWhoFalls like this.

  7. #7
    Member pithy's Avatar
    Join Date
    Aug 2010
    Posts
    7,080

    Re: Crystal Fitting....(Challenge accepted)

    Quote Originally Posted by Archer View Post
    I agree, the G-S press is one I use often - the cabinet was worth the price just for this press IMO (didn't cost much also so that helps): Easy to install the PA/PHD or similar style crystals using this press, provided the case is not a front loading design. In that instance, the crystal lift or brand specific tool can be used for installation as well as removal. Cheers, Al
    Quality hand pliers or a good bench mounted press - fitted with the right accessories - perform very well in this role. The cabinet has a huge advantage over both these types of tools in that it allows the use of both hands to position the crystal and bezel while simultaneously tensioning the crystal and allowing for subtle adjustment of that pressure. If you use one every day you tend to forget about the pleasure of this feature.

    The crystal lift - particularly in the hands of one inexperienced in its use or more properly experienced in its disuse - is generally a tool to be avoided. This is a poor tool indeed compared too the factory insertion tools. Start with a set of Mido compression wrenches as they have been frequently available and add to that collection with other brands. You can always sell the overlapping ones or have backups in place. - - - Perhaps someone will post some factory literature outling their use. ----- Use of a quality claw type tool is sometimes unavoidable. Be prepared to break or scratch or gouge some crystals. Sometimes breakage occurs with any crystal installation method. The goal is to make that occurence as infrequent as possible. Some of these installations may be salvageable with polishing.
    Attached Images Attached Images

    TheManWhoFalls likes this.

  8. #8
    Member pithy's Avatar
    Join Date
    Aug 2010
    Posts
    7,080

    Re: Crystal Fitting....(Challenge accepted)


  9. #9
    Member pithy's Avatar
    Join Date
    Aug 2010
    Posts
    7,080

    Re: Crystal Fitting....(Challenge accepted)

    BB Crystal Catalog courtesy of Mark:

    http://www.watchandjewelrysupplies.c...rence_Book.pdf

  10. #10
    Member
    Join Date
    Dec 2008
    Location
    Alberta Canada
    Posts
    580

    Re: Crystal Fitting....(Challenge accepted)

    Crystal lifts are Ok, but I usually reach for the crystal press. Some watches it's an absolute necessity, as the bezel angle doesn't have enough room to fit a lift on. Watches like Rolex's it's also a necessity as you need to use it to squeeze the bezel back on around the crystal. A press might be a little harder for a novice to use, as you can quickly crack a crystal with the wrong chuck and too much pressure.
    If your going to get a press look for a vintage GS or one with nice soft plastic chucks.

Page 1 of 3 1 2 3 LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

    Similar Threads

    1. Omega Seamaster Crystal Fitting
      By systeman in forum Omega
      Replies: 3
      Last Post: June 13th, 2014, 15:12
    2. Replies: 64
      Last Post: July 16th, 2013, 20:07
    3. Replies: 2
      Last Post: April 26th, 2011, 21:09
    4. Helping the Noob Fitting a Seiko 7006 Crystal
      By PR™ in forum Watchmaking
      Replies: 4
      Last Post: November 24th, 2010, 01:52
    5. crystal fitting question...
      By portroyal in forum Watchmaking
      Replies: 6
      Last Post: May 8th, 2010, 15:24

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts
    •