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Repairing sanding belts?

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  • psomero
    replied
    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.

    Leave a comment:


  • Spades
    replied
    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.



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  • old mart
    replied
    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.

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  • Bented
    replied
    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.
    https://gokimco.com/products/loctite...UaAvFjEALw_wcB

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  • Jonesy
    replied
    edit
    Last edited by Jonesy; 01-02-2022, 03:51 PM.

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  • J Tiers
    replied
    Originally posted by challenger View Post

    So where does one get thermoset adhesive to repair the 185 1/2" belts broken by non-use 😬
    Don't know, never looked. The old degraded crap is so hard to remove entirely that I just used the belts for hand strip-sanding

    Leave a comment:


  • boslab
    replied
    Has anyone seen the new(ish) hot melt PU adhesives, they come in a metal cartridge you stick in the gun, may well be the abrasive belt solution
    https://www.gluegun.com/collections/...iant=262070240
    im seriously thinking of investing
    mark

    Leave a comment:


  • challenger
    replied
    Originally posted by J Tiers View Post

    A "thermoset" glue is one which does not soften with heat. You are confusing "thermoset" with "thermoplastic". Thermoset glues have components which react when heated to change into a different material that holds the parts together, and which is not heat-sensitive. Like "Bakelite", which does not soften to any particular degree with heat, but is a thermoset material, where phenol and formaldehyde react to make a hard solid.

    I have NEVER seen a manufacturer glue joint fail by softening with heat.

    What every stinking one of the SOB's has done is soften and turn gooey while sitting on the shelf waiting in reserve. Then when put in place, they hold for one turn around the pulleys, or maybe a few more, only to literally slide apart, leaving a sticky residue on each side of the joint.

    That is without any work being sanded, so no heat buildup.
    So where does one get thermoset adhesive to repair the 185 1/2" belts broken by non-use 😬

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  • J Tiers
    replied
    Originally posted by Spades View Post
    ............................................

    The original glue used is a thermoset which creates problems when sanding steel, aluminium etc. where the developed heat softens the glue, it also has ageing problems where it fails after about 12 months.

    ................................
    A "thermoset" glue is one which does not soften with heat. You are confusing "thermoset" with "thermoplastic". Thermoset glues have components which react when heated to change into a different material that holds the parts together, and which is not heat-sensitive. Like "Bakelite", which does not soften to any particular degree with heat, but is a thermoset material, where phenol and formaldehyde react to make a hard solid.

    I have NEVER seen a manufacturer glue joint fail by softening with heat.

    What every stinking one of the SOB's has done is soften and turn gooey while sitting on the shelf waiting in reserve. Then when put in place, they hold for one turn around the pulleys, or maybe a few more, only to literally slide apart, leaving a sticky residue on each side of the joint.

    That is without any work being sanded, so no heat buildup.

    Leave a comment:


  • DR
    replied
    I used to buy custom size sanding belts from converters. Converters are companies that make belts to your size requirement from raw stock. They're usually independent from the big guys like 3M, Norton, etc, so they can't supply belts in the newer, proprietary super abrasive types. Surprisingly custom belts aren't very much more than a close in size standard belt.

    Jet and Western Abrasives in Los Angeles is a place I used quite a bit. That's one company and not affiliated with Jet Machinery. They were always helpful in suggesting an abrasive they had in stock for the material we were sanding. They will gladly give advice, but they won't sell direct to users, you have to order through a local industrial supply outfit.

    I always wondered if they wouldn't be a source of info on belt repair materials. A phone call might yield some good info.

    Leave a comment:


  • Spades
    replied
    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.

    The original glue used is a thermoset which creates problems when sanding steel, aluminium etc. where the developed heat softens the glue, it also has ageing problems where it fails after about 12 months.

    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 no idea how this would work on larger belts and the quantity of glue required may make it uneconomical.

    Leave a comment:


  • dian
    replied
    it was not locktite but some instant glue designed as flexible from a local diy store. name and picture wont help much because you probably wont be able to get it over there any way, its several years back.

    Leave a comment:


  • Rich Carlstedt
    replied
    Wow,$ 70 for .7 of an Ounce....that seven tenths of an ounce !

    Rich

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  • Bob Engelhardt
    replied
    Originally posted by dian View Post
    i have glued 2x72 belts with flexible instant glue in the past. no problem, no tape. the hardes part was to ge the alignment right.
    Like Loctite 4902? $$$$!

    Leave a comment:


  • Rich Carlstedt
    replied
    Originally posted by dian View Post
    i have glued 2x72 belts with flexible instant glue in the past. no problem, no tape. the hardes part was to ge the alignment right.
    Name or photo please

    Rich

    Leave a comment:

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