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  • Indicator Crystal Replacement

    Tried my hand at replacing an indicator crystal this evening. I picked up 3 older Ames indicators, which are functioning well but have yellowed crystals. Ames is still making indicators, and were able to provide me with some replacement crystals.

    I tried pressing the crystal in at first, but it's quite oversized and needs to be domed. From what I understand Ames is more domed than other manufacturers, making this a bit more difficult. I attempted to dome it using the rim of a lid slightly smaller than the crystal and a small cap pushing down into the middle first lid, but ended up buckling the edge a touch causing it to sit not quite right. It's probably functional as is, but I'd like to refine the process a bit more before I attempt the other two.







    I've seen two ways of doing this, and the methods differ quite a bit.

    The first is to turn a wood form and drape a heated crystal blank over it. This would be possible, I have the old crystals and would be able to use them to match the profile.

    The second is to improve my press method, either making a press from a drill press or purchasing one.

    I'm feeling that because of the high dome required for these particular indicators that the first method may be the better one that I may try next.

  • #2
    Maybe they are pressed in from the back. Heating them up would make them more pliable.

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    • #3
      There is a watch tool specifically for that, which functions as your make-do version does.

      I have several indicators that need new crystals, and I have the tool, but I have neither the material (yet) nor the "dies" of the right size to do the pressing. The tool is more watch sized, and the indicators in question are mostly larger than the "dies" I have. The tool is missing a couple, and I have not made them yet. They are not that odd, mostly smooth plastic.
      1601 2137 5683 1002 1437

      Keep eye on ball.
      Hashim Khan

      If you look closely at a digital signal, you find out it is really analog......

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      • #4
        Here is a video showing how to use the watchmaker's tool: https://www.youtube.com/watch?v=2Gz7V9P7nJ8 . You can find the tool on ebay. Either low-price imports or used vintage for a bit more. There are also available new, expensive.

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        • #5
          The pressed in plastic crystal style needs outward force to hold it in the bezel, so imo compression is needed. I never heard of a watch being done by heat but maybe....I'd thinking if it softens it, its a thermoplastic and it will more likely deform as you try press it in.

          The press linked to above is excellent. Surprised to see its branded Mitutoyo, that they make enough crystal presses to be worth their while,. Mine is a Bergeon, so likely made my Horia.

          You could make plastic dies for the DP and use this approach.

          Another one is the pincer style like this. https://www.youtube.com/watch?v=3n1bdbp7CDk. If you didn't want to make something for the DP, its a more reasonable outlay than a full press and dies.

          I haven't done anything about it, but thought it would be neat to figure out how to make your own....they're not hugely expensive but it would let you get on with it instead of waiting for a crystal in the mail
          Last edited by Mcgyver; 07-17-2020, 07:32 AM.
          in Toronto Ontario - where are you?

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          • #6
            Originally posted by Tom S View Post
            Tried my hand at replacing an indicator crystal this evening. I picked up 3 older Ames indicators, which are functioning well but have yellowed crystals. Ames is still making indicators, and were able to provide me with some replacement crystals.

            I tried pressing the crystal in at first, but it's quite oversized and needs to be domed. From what I understand Ames is more domed than other manufacturers, making this a bit more difficult. I attempted to dome it using the rim of a lid slightly smaller than the crystal and a small cap pushing down into the middle first lid, but ended up buckling the edge a touch causing it to sit not quite right. It's probably functional as is, but I'd like to refine the process a bit more before I attempt the other two.







            I've seen two ways of doing this, and the methods differ quite a bit.

            The first is to turn a wood form and drape a heated crystal blank over it. This would be possible, I have the old crystals and would be able to use them to match the profile.

            The second is to improve my press method, either making a press from a drill press or purchasing one.

            I'm feeling that because of the high dome required for these particular indicators that the first method may be the better one that I may try next.
            In the last picture the crystal looks to have buckled a bit, or is it just a reflection??

            Since you said you attempted to dome it, are these replacements crystals flat or somewhat pre domed ?? Perhaps they are slightly over sized and you need to carefully reduce the dia.

            Like Mcgyver said, they need a slight outward force to stay in place. Heating the crystal may relieve it of the outward force needed to stay in place or may cause it to distort once you have pressed it in place.

            JL.....................

            Comment


            • #7
              Long ago I replaced the crystal in one of my indicators. I tried and failed at several of the more complex techniques; using heat was especially failure-ful. I was successful at pressing in a slightly-oversize one. I just used poly-c from a hobby shop, 0.030 IIRC and whatever tooling I made was so simple that I didn't bother saving it for future use.

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              • #8
                I think I'm going to give making my own press parts using some scrap UHMW we have floating around work. It's not that complicated of tooling, should be pretty straight-forward.

                The crystals as I received them were just flat pieces of polycarbonate, I'll measure up the thickness when I get a chance. I was given the impression by Ames that these were ready to go, but I'll check the diameter as well. Making your own shouldn't be that difficult, hold the polycarbonate between two pressure pads and turn to size. You can add bevels if needed then as well.

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                • #9
                  https://www.youtube.com/watch?v=vynTUg6S3DU Ames crystal replacement. Use a golf ball for a pusher.

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                  • #10
                    Originally posted by Tom S View Post
                    Making your own shouldn't be that difficult, hold the polycarbonate between two pressure pads and turn to size.
                    for flat crystals you're probably right, but most of them are domed....so I'm doomed unless I make some sort of former (I guess using heat and the right kind of polycarbonate or acrylic) me thinks.
                    in Toronto Ontario - where are you?

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                    • #11
                      Material thickness is measuring at about .020". Quick look online is finding the thinnest easily available polycarbonate is about .030.

                      Tried again with a golf ball, got closer but when I was just about there the polycarbonate crinkled and I had the same issue. I'm debating whether a bit of pre-heating before installation might help somewhat, but I'm not sure if that would make it more or less likely to crinkle.

                      Don't the domed crystals start out as flat and get their dome when pressed into the bezel? Or do some come pre-formed? If you want to form them you could try either a light vacuum or pressure forming process and trim to final size after forming.

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                      • #12
                        The come preformed, a domed crystal is still domed when out of a watch (or indicator). Lots of different profiles as well as flat ones. I think you're trying to bend it too much...crystal diameters come in .1mm increments, so you get one that is ust putting a little out pressure on the bezel, there's not that much compression put into it. Perrins in Toronto or we still get free shipping with china ebay stuff if you want buy one.
                        in Toronto Ontario - where are you?

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                        • #13
                          Originally posted by Bob Engelhardt View Post
                          Long ago I replaced the crystal in one of my indicators. I tried and failed at several of the more complex techniques; using heat was especially failure-ful. I was successful at pressing in a slightly-oversize one. I just used poly-c from a hobby shop, 0.030 IIRC and whatever tooling I made was so simple that I didn't bother saving it for future use.
                          I was rummaging in my plastics box and came across the poly-c that I used: it was 0.040, not 0.030.

                          Re: domed crystal. Using flat material larger diameter than the ring/bezel and forcing it into the ring will create a domed crystal.

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                          • #14
                            I use this tool to replace <.001"> drop indicator crystals, only $16.00 + shipping, can't be beat.
                            https://www.amazon.com/HFS-0-001-IND...xpY2s9dHJ1ZQ==

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                            • #15
                              Crystals for indicators start as a flat piece and then a tool is used to deform them and they spring back into places as a dome in the ring.

                              Long Island Indicator shows one of the presses, you should be able to rig up something similar. You can probably buy pre-cut crystals from them too. I have dealt with them in the past and they were very helpful.

                              http://www.longislandindicator.com/p233.html

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