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How to Re-Glue Certain Separated Belt Sanding Belts

carrdo

Active Member
Hi All,

I have a number of different 1" wide abrasive belts purchased over the years for my belt sander which I use a lot.

For some reason after about six months, whether used or not, the reinforced glued joint on these belts has separated on me. Now, these belts are not that expensive to buy but I don't want to be in the middle of a project, have the belt separate and everything come to a screeching halt as a result. A review of many other metal working web sites has indicated that this is a common problem.

Many solutions have been proposed but none of them really work. I have come up with something which works for me but you don't get something for nothing so...

I will first discuss why I think these belts fail and always will.

First, the reinforced glued belt joint has to be very strong. The belt sander which I have puts the abrasive belt under a lot of tension to keep it tracking and straight when belt sanding.
Second, the reinforced glued joint has to remain totally flexible under a high RPM load as it goes around numerous pulleys which flexes the abrasive belt back and forth continuously.
Third, abrasive belt sanding can generate a lot of heat in addition to the above which the belt joint has to absorb and not soften or lose any strength under these conditions.
Fourth, the abrasive belt joint has to be very thin with no abrupt changes in surface composition or thickness which would induce shock or impact as it follows its serpentine path over and over again.

As far as I have been able to determine, there is no abrasive belt here in Canada (or anywhere) which can meet all of the above conditions for long.

So, is there a practical solution to this dilemma or as practical as possible? Yes, but..

So here is what I have found through experimentation and experience.

Some of the products I use cannot be found in Canada or cannot be imported here legally because of what they contain or have been banned as being too hazardous.

To start, I first clean the ends of any separated belts of their original glue. The best material for this I have found to be "Spot Remover" or perchlorethylene which used to be used in dry cleaning. I don't think it is available anymore to the general public as it is carcinogenic but I have an old bottle of it which I use very sparingly and only outdoors.

Second, scarify each end of the cleaned belt ends using coarse sandpaper and a sanding block.

Third, cut off a piece of Scotch Brand (there may be others) bi-directional filament tape (it is only 0.008" thick but super strong) slightly wider and longer than the original belt splice.

Fourth, push the ends of the belt together and apply "the original Weldwood contact cement" to the (underside) ends of each belt end.

Here I have to say something. There is no other glue or contact cement here in Canada which is equivalent to what I have just specified and nothing else will work. Yes, one can purchase a can of it as shown in the last photo through Amazon.ca but don't. Amazon or Amazon.ca is not the supplier, they use third party suppliers, who may, or may not, be aware that this contact cement is banned here as being too hazardous (at least to the general public). Also, as a result, it is a ridiculous price compared to what it costs south of the border even if someone will ship it here. As well, there is a practical reason why not to buy such an amount unless you want to re-splice hundreds of belts all at the same time. For as soon as you open the can, whatever solvent or solvents there are in it, which keep the glue liquid, they will start to evaporate and no matter how tightly one reseals the can, after about 3 months the entire can contents turn into a solid rubbery block making 99.8% of the can's contents useless. It can be purchased south of the border cheaply in a small 20 ml tube and this is what I now use. I have picked up a tube on a recent visit in the USA.

to be continued.
 

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  • 517 A Selection of One Inch Wide Abrasive Belts that I Use.jpg
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  • 518 Removing All Traces of Existing Splice Glue.jpg
    518 Removing All Traces of Existing Splice Glue.jpg
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  • 519 Scarifying Each End of the Abrasive Belt.jpg
    519 Scarifying Each End of the Abrasive Belt.jpg
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  • 520 Special Bi-Directional Filament Tape Which is Only Eight Thousands of an Inch Thick.jpg
    520 Special Bi-Directional Filament Tape Which is Only Eight Thousands of an Inch Thick.jpg
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  • 521 Special Rubberized Contact Cement.jpg
    521 Special Rubberized Contact Cement.jpg
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To continue.

The cut off piece of bi-directional filament tape is then set over the glue aligned ends of the abrasive belt. It has a glued side on it and this side is the one set over the glue aligned ends of the abrasive belt. Then, with a wallpaper seam roller, roll flat the filament tape on the back of the abrasive belt. Do this with pieces of wax paper set under the abrasive belt and over the filament tape. When and after rolling everything must be kept in place as seen in the second photo as the natural tendency of the abrasive belt is to twist out of place at the joined ends.

After a minute or so carefully transfer the glued joint to your bench vise and using thin wood strips clamp the entire assembly thoroughly as seen in the third photo. Leave it this way for at least 24 hours then slowly release the clamping pressure in stages (every couple of hours). Finally, remove the wood clamping strips, wax paper and trim away any excess filament tape.

One of my re-glued abrasive belts, seen in the last photo has been on the belt sanding machine for the last six months and has not failed yet. It runs smoothly and one cannot feel or hear the remade joint as it passes over the machine pulleys. One thing I do is limit my grinding pressure to moderate so as not to create any excessive heat build up.
 

Attachments

  • 522 Glue Applied Ends of the Abrasive Belt are Aligned and Set Together on the Glued Filament ...jpg
    522 Glue Applied Ends of the Abrasive Belt are Aligned and Set Together on the Glued Filament ...jpg
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  • 523 After Rolling to Keep Everything in Place.jpg
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  • 524 (Long Term) Clamping After Applying New Glue to the Back of the Abrasive Belt and Bi-Direc...jpg
    524 (Long Term) Clamping After Applying New Glue to the Back of the Abrasive Belt and Bi-Direc...jpg
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  • 525 The Re-glued Belt Re-installed and Running.jpg
    525 The Re-glued Belt Re-installed and Running.jpg
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For some reason after about six months, whether used or not, the reinforced glued joint on these belts has separated on me.

Is this the sort of thing you should put in a vacuum sealed container (or maybe filled with CO2 or Nitrogen) to stop the adhesive from deteriorating over time?
 
Nice write up. At the one job we threw away piles of belts mostly from people really leaning in to them. Never thought about gluing them back together. One of the things I miss from that shop is having a good belt grinder. Also they had an 80 ton iron worker that made my job so fast and easy.
 
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