Thread: disc sander velcro issues

I haven't had any experience with a 12 in disk sander and velcro, but plenty with a 5in angle grinder and velcro metal polishing and surfacing. Our AG's ran 8 hours a day minimum at about 2/3 speed, doing preparitory surface finishing of SS and mild steel furniture frames prior to plating, brushing, or mirror polishing.

We used a self adhesive sheet material (same brand material is available from Sandpaperman as sheets) which we purchased off the roll from one of our abrasisve suppliers, and then rough cut disks to apply to the backing pad, and trimmed with a blade when mounted with the AG running at about 1000RPM. We typically achieved about 4-5 weeks (150 -200hrs or more) from a pad before the hooks were not gripping well at the outer edges. This is attributed to prolonged high temperature/pressure from continuous operation. We had very few glue failures, generally our glue issues related to peeling shot hook sheets off the disk and clearing glue residues off the backing disk. We kept some rough used linisher belts (60 grit blunted by descaling SS bar) on hand and swapped them onto one of the polishing lathes to clear the glue residue, polishing lathe driving belt and AG driving backing pad at full speed. This combo ripped the bulk of the glue off, and heated the residual glue enough to soften it so we could scrape it off.

The only times we had a glue failure was if the hook sheet was applied to a not perfectly cleaned pad, or when we purchased cut to size Norton hook sheet disks, if we started to apply the the disk and then peeled it to realign it on the pad. We overcame the later issue by rough cutting oversize and trimming after mounting.

Obviously, as a disk sander, there is a tendancy to use the outer area of the disk more frequently and possibly aggressively due to the higher surface speeds so this is the area that suffers the greatest effects of heat buildup both in the hooks and the adhesive. Other possible issues include edge contamination in storage or use, possiblity of old stock with aged adhesive etc. I would suggest the Sandpaperman sheet approach if the sheet is large enough to provide your disk.

Thanks malb - I'll see if Sandpaperman has the stuff in big enough pieces to suit a 300mm disc. I need some sanding roll for my drum sander from him anyway, so will give him a call next week.

I'm not keen to go another one from Carbatec, as I seem to recall that it wasn't cheap in the first place.

I hadn't considered that heat buildup could be the problem here, but you may well be right. It would explain why the outside has given up first, while the centre of the disc is still very firmly attached.

Cheers

So I guess the lesson from this is to change the sanding disc more often (i.e don't keep flogging a really worn disc), so you won't have to press so hard and cause excessive heat buildup, then the velcro backing pad won't start to detach.......

Sanding discs are certainly cheaper than velcro backing pads, that's for sure !!

John make sure that a fine filament has not remained behind...how do I know I just had similar problem on Scheppac disc sander when i went to replace the velcro wasted a whole new piece. Clean with Eucalyptus or Metho NOT mineral turns which has oil base.

Originally posted by Mr Brush

I have a Carbatec 300mm disc sander. Some time ago I decided to use the velcro-backed sanding discs as they are so readily available, and now I have a generous supply of these stashed away in various grits. The velcro/backing combination is flat enough for the work I do.

Obviously I first purchased and fitted the velcro adapter sheet to the metal disc of the sander, taking care to degrease the metal surface thoroughly before applying the self-adhesive velcro pad. This has worked fine for about 12 months (and several disc changes), but now I find that the velcro backing pad is coming away from the metal disc around the edges. This means that when I pull on the velcro sandpaper to change a disc, the whole backing comes off with it around the edges..... I know it's too late now, but next time you might get a few more disc changes by just re-sticking the bits of the backing sheet which were lifting

After much wrestling (the adhesive has only come away around the edges, and is still stuck in the middle like sh** to the proverbial), I have the velcro adapter sheet off the machine. I note that it has a thick rubbery adhesive backing which is very well bonded to the back of the velcro sheet (i.e. darn near impossible to get off) - the problem is just that the adhesive layer doesn't want to stick to the metal disc of the sander any more.

Options:

(1) Buy another velcro adapter sheet, stick it on, and likely have the same thing happen again. While this might initially seem costly, it seems to be the what you should expect. The velcro adaptor makes changing sanding sheets easy, the down side is the pain involved in removing the adaptor when it wears out.

(2) Remove the old rubbery adhesive backing layer from the velcro adapter (which won't be easy), then use some kind of contact glue to stick it back onto the metal disc permanently. I'm just concerned that the backing of the velcro adapter seems to be made from a plastic resistant to most solvents (including acetone), so contact glue may not stick to it very well. Did you try lacquer thinner to remove the glue? The glue is almost certainly one of the rubber cements and these soften and can be "washed off" with thinner. Make sure you're working in a very well ventilated area with no ignition sources. Heat also works really well -- just don't mix a heat gun with the lacquer thinner.

(3) Leave the existing adhesive layer on the velcro adapter sheet, but apply spray contact adhesive on top of this to stick the whole gubbins back onto the metal disc. Not a good idea IMO

Has anyone else had this problem, or are there any velcro experts out there who can advise on the best solution?? I've done a search, but nothing I've found really covers this.

Any advice much appreciated.

Ray - I've thoroughly cleaned and degreased the metal surface (using acetone), so it should be OK. Did you use a fresh shop-bought velcro backer disc, or were you able to buy it in sheet form from somewhere?

Ian - unfortunately the bits around the edge had completely lost their "stick", and would come away from the metal surface as soon as the disc was spinning. I hadn't thought of trying lacquer thinner to remove the glue layer from the old pad, so will give that a go. I'm not convinced that the cleaned disc will stick properly with contact adhesive, but there's nothing to lose by giving it a try. I have a can of the 3M spray contact somewhere.

If all else fails, I'll try Sandpaperman for velcro backing sheet, or (last resort) but a new one from Carbaforbes.

Cheers

Velcro Sheet - 305 mm x 500 mm | The Sandpaper Man

A1200 | 305mm (12") Velcro Backing Disc | machineryhouse.com.au

Originally Posted by Mr Brush

Ray - I've thoroughly cleaned and degreased the metal surface (using acetone), so it should be OK. Did you use a fresh shop-bought velcro backer disc, or were you able to buy it in sheet form from somewhere?

Ian - unfortunately the bits around the edge had completely lost their "stick", and would come away from the metal surface as soon as the disc was spinning. I hadn't thought of trying lacquer thinner to remove the glue layer from the old pad, so will give that a go. I'm not convinced that the cleaned disc will stick properly with contact adhesive, but there's nothing to lose by giving it a try. I have a can of the 3M spray contact somewhere.

If all else fails, I'll try Sandpaperman for velcro backing sheet, or (last resort) but a new one from Carbaforbes.

Cheers

John I was using a Hook n loop bought in sheet form from place in Minto/Campbelltown 420 wide by just under 1m an off cut if I recall. All Purpose Abrasives - Contact Us

The filament was off the original. Yes I agree thinners would be great for cleaning as it leaves no residue just watch plastic parts as it can dissolve some.

Heat transfer will effect the glue.

Originally Posted by Mr Brush

Ian - unfortunately the bits around the edge had completely lost their "stick", and would come away from the metal surface as soon as the disc was spinning. I hadn't thought of trying lacquer thinner to remove the glue layer from the old pad, so will give that a go. I'm not convinced that the cleaned disc will stick properly with contact adhesive, but there's nothing to lose by giving it a try. I have a can of the 3M spray contact somewhere.

If all else fails, I'll try Sandpaperman for velcro backing sheet, or (last resort) but a new one from Carbaforbes.

Cheers

Hi Mr Bush

my first job after leaving school was making contact adhesive.
depending on the glue formulation, contact adhesive will stick as well as the proverbial so I have no doubt that contact will work.

besides if you don't use a velcro backer on the steel disc, you'll be attaching sanding sheets directly to the disc with some form of contact