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Making a drive belt for a Hermes MV engraver

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  • Making a drive belt for a Hermes MV engraver

    I'm not real familiar with engravers but I figured $20 wasn't too bad a deal even though it was missing the drive belt. No problem I said, I'll just make one from o-ring material and I did. It lasted for about 3 seconds then broke. So I made another one, being very careful to clean the Buna N o-ring material, cut the ends square, use new super glue and glue the ends square. It lasted about 3 seconds, breaking at about 2000 rpm as the motor was ramping up to 10,000 rpm.

    So I looked at the New Hermes web pages and discovered the o-ring drive belts are made from silicone. So I ordered silicone o-ring material and made a new one. 14" of 1/8" diameter silicone o-ring stock, 100% silicone adhesive sealant, 1/8" clear heat shrink tubing. Cut the ends square, place a small dab of silicone on one end and slide the ends into the heat shrink which keep them in line. let set 24 hours or so before cutting the heat shrink off.





  • #2
    Here's the engraver the belts goes to. If any of you guys know about engravers I like to hear what you have to say.

    Ron




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    • #3
      neat, never heard of that. I like the heatshrink trick for keeping them aligned. Cutting each end at 45deg might give you a slightly stronger joint, though trickier to get the angles just right.

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      • #4
        Well, I'm anxious to hear how this one does.

        And let me be the first smartass to say I think it will vibrate a bit with that heat shrink splice.
        .
        "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

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        • #5
          I don't think you meant smartass...

          He says he is removing the tubing...

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          • #6
            I'll be watching this one..... I have had about zero success using silicone sealant as a tension adhesive.

            Maybe it will work for you.
            1601

            Keep eye on ball.
            Hashim Khan

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            • #7
              Originally posted by mattthemuppet View Post
              neat, never heard of that. I like the heatshrink trick for keeping them aligned. Cutting each end at 45deg might give you a slightly stronger joint, though trickier to get the angles just right.
              I actually considered doing just that. But with two failures under my belt I didn't want to get too involved, especially since silicone o-ring material is OEM.

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              • #8
                Hmmm......I believe that engraver is the same one I had. Sold it recently because the little engraving I need can now be done on the CNC.

                As to the belt the only belts of this type I'm familiar with were made of urethane with a heat weld. A local belt maker had a hot wire cutter and quickly pushed the cut ends together while the belting was still liquidy soft. The weld cools quickly, any lumps can be ground off and the belt used immediately..

                BTW, it appears the "tires" for my Delta bandsaw were made this way since the weld appears obvious. The tire welds hold very well with all the stretching you need to do to get it on the bandsaw wheel.

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                • #9
                  I also didn't think you could glue cured silicone with silicone adhesive.

                  We have 1000's of miniature round belts on our conveyor. They are typically urethane and for repair replacements we joint then with a hot disc on a soldering iron - they last years, and the conveyor runs 15 hours a day.
                  Last edited by lakeside53; 02-27-2019, 01:44 AM.

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                  • #10
                    You could also make from leather cord with a staple just like the old sewing machines.

                    I don't think 24 hours is enough for the silicone to cure under the sleeve in that sealed condition
                    Last edited by Noitoen; 02-27-2019, 01:49 AM.
                    Helder Ferreira
                    Setubal, Portugal

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                    • #11
                      I have to ask- is that o-ring material meant to be joined? If so it must be a special formulation that can bond with uncured silicone. I've never heard of such a thing, but that doesn't mean it doesn't exist.
                      I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                      • #12
                        Originally posted by DR View Post
                        ....
                        As to the belt the only belts of this type I'm familiar with were made of urethane with a heat weld. A local belt maker had a hot wire cutter and quickly pushed the cut ends together while the belting was still liquidy soft. The weld cools quickly, any lumps can be ground off and the belt used immediately..
                        ....
                        Originally posted by lakeside53 View Post
                        .....
                        We have 1000's of miniature round belts on our conveyor. They are typically urethane and for repair replacements we joint then with a hot disc on a soldering iron - they last years, and the conveyor runs 15 hours a day.
                        I have had several heat-welded urethane belts working for years, on a jeweler's lathe and a little drill press.

                        Silicone is such a slippery surface, and the sealant is not a good glue..... Plus silicone does not heat-weld that I know of. I'd be betting the OEM silicone belts are molded in one piece, or maybe joined mechanically,

                        But the proof is in the results.

                        I agree on the time taken. The sealant is almost surely some form of RTV material, which needs moisture in the air to cure, unless it has been mixed, after being squeezed out of the tube, with a catalyst (I think some metallic compounds are catalysts for it). Obviously it cannot have any catalyst in it when it is in the tube, or it would cure in there.

                        With the tube around it, there may not be much access to moist air, and it may cure very slowly. The gasket type silicone may cure more rapidly, as it is designed to cure in a similar sort of situation with limited air access, but I do not know if it is any good as an adhesive.
                        1601

                        Keep eye on ball.
                        Hashim Khan

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                        • #13
                          I hope the silicone stays together. I had to replace the drive belt on a New Hermes cutter grinder and found that the old one was urethane. I got some round urethane stock and joined it withheat as described in one of the other posts. My two New Hermes pantographs use flat belts. They are both larger machines than yours. I have a number of extra 1/8 inch diameter cutters that probably fit your machine and can sharpen them to requirements as to angle and point width.

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                          • #14
                            Not trying to be a downer but I cannot see this working - iv joined O-rings with super glue that were made of neoprene or butyl rubber with some success but never silicone,

                            Now their might be some kinda special glue that's formulated to join silicone together but im pretty sure it's not silicone tub and tile caulk...

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                            • #15
                              Just to be clear, I've never done this before so it might fail just like my first two attempts with buna-n. After all I've come to realize there are some pretty sharp individuals on this site. So gentlemen I'll give it my best shot and if need be I'll try something else.

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