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Repairing sanding belts?

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  • #46
    Finished a job this past Tuesday, printer mandrels with 40 taper brass cores.
    The covers are 2 pieces of 20% glass filled polycarbonate, the customer drawing specified Loctite 4011 medical device adhesive at the joint.
    The adhesive is excellent and may be worth a try on abrasive belt joints, it is not inexpensive however.


    • #47
      We inherited a number of linisher belts which fit our machine at the museum, but they only last about one minute before the joint fails. Clive took a couple home and reglued them sucessfully and then did all the rest. I will ask him exactly how he did it and what glue he used.


      • #48
        A follow up to my earlier post, part of which I reproduce below :-

        "I had a problem with a substantial quantity of smaller 12mm wide belts coming apart at the glue joint. I tried numerous methods and glues which all failed miserably within just a couple of rotations.

        "I have recently had very good success with Loctite Powerflex super glue. It is a rubberised glue which has lots more flexibility which I believe has been the main problem in my case where the belt wheels are quite small in diameter (about 15mm).
        I scrape all of the old adhesive off both mating surfaces with a blade, then lightly sand with 120grit, and then wipe over with Acetone.
        The Acetone shows up any glue that has been missed and needs to be cleaned off.
        I then smear a thin coat of the Powerflex over the entire face of one joint surface.
        Align the faces and press together, clamp and leave it to set for a couple of hours - you may get away with less time.
        It's important to ensure that the leading edge of the joint is well stuck as this appears to be the primary failure point.

        I have since reglued around 20 of the belts using the above method with just one failure which I decided was possibly due to insufficient removal of the old adhesive.
        A subsequent rework of that failed belt resulted in complete success.

        I have a piece of railway line that I have now tested a couple of these repaired belts on, actually sanding a groove in the steel with no failure or even a sign of the joint coming apart.

        After that workout the joints are still tight to the point that I cannot prise them apart without tearing the belt material.

        Some lessons learned are:-
        1. The old glue must be totally removed, which I do by scraping with a snap knife blade,
        2. Wiping with Acetone not only cleans the surface but also displays any remaining old glue as a slightly darker colour.
        3. You must smear a thin coating of the glue over one entire surface and then clamp it to ensure the edges are locked together, just a few minutes works for me.
        4. The glue comes in an applicator which is pretty much useless, when you think the tube is empty there is still about a quarter remaining, take it out of the applicator and you will get a lot more value. I have repaired 20 odd belts and still have glue remaining in the first tube.


        • #49
          3M 300 LSE transfer adhesive. Less than 5 thou thick and ultra flexible but sticks like crazy.

          Also great for doing parts on a fixture plate. Use methanol to get it off if you don't want to pry a lot.