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Trouble Holding Sanding Disks to the Platen

projectnut

Stainless
Joined
Mar 4, 2006
Location
Wisconsin
I've had have a Rockwell/Delta belt/disk sander for well over 20 years. The machine runs well, but lately I'm having trouble keeping the 12" disks glued to the platen. If I use the machine on a daily basis all seems well. However if it sits for a week or so the disks just seem to fall off.

At first I thought it might have been the quality of the disks I was purchasing. I had a bunch of self adhesive ones from a local farm store I thought might have been either old or of inferior quality. More recently I purchased a dozen ARC brand self adhesive ones from McMaster. I'm still having the same problem. With regular use they stay attached. With intermittent use they fall off in a week or so.

I've cleaned the platen of all residue, and even wiped it down with alcohol, but the problem still persists. When the disks come off they still seem to have plenty of adhesive. One thing I did notice with the McMaster disks is when they arrived they weren't perfectly flat. There was some arc on them in that they were shipped in a box slightly smaller than the diameter of the disks. Consequently they were on an angle in the box and may have developed an arc in transit.

I laid them flat on a shelf and put some weight on them to attempt to flatten them to no avail. Whenever I take one off the shelf the arc returns within a short period of time.

Any suggestions would be appreciated.
 
I've had have a Rockwell/Delta belt/disk sander for well over 20 years. The machine runs well, but lately I'm having trouble keeping the 12" disks glued to the platen. If I use the machine on a daily basis all seems well. However if it sits for a week or so the disks just seem to fall off.

At first I thought it might have been the quality of the disks I was purchasing. I had a bunch of self adhesive ones from a local farm store I thought might have been either old or of inferior quality. More recently I purchased a dozen ARC brand self adhesive ones from McMaster. I'm still having the same problem. With regular use they stay attached. With intermittent use they fall off in a week or so.

I've cleaned the platen of all residue, and even wiped it down with alcohol, but the problem still persists. When the disks come off they still seem to have plenty of adhesive. One thing I did notice with the McMaster disks is when they arrived they weren't perfectly flat. There was some arc on them in that they were shipped in a box slightly smaller than the diameter of the disks. Consequently they were on an angle in the box and may have developed an arc in transit.

I laid them flat on a shelf and put some weight on them to attempt to flatten them to no avail. Whenever I take one off the shelf the arc returns within a short period of time.

Any suggestions would be appreciated.

I covered the disc on the machine with a thin but strong double sided tape.

Regards Tyrone.
 
I’ve always used disk adhesive as well. The kind that comes in a heavy cardboard tube and is softened by friction heat. If the disk isn’t sticking, peel it off and use a wooden stick on the platen to heat, soften and smooth the adhesive, then re-attach. With a plain disk it doesn’t always hold perfectly, but with a self-adhesive disk it does.
 
I use sanding discs on an angle grinders (5" & 9") and if I leave them outside they naturally want to curl. This is when mounted to the grinder. If I just leave an old used one out it will curl up into a tube.
I think moisture has something to do with causing the curl. I can put weights on them but if you get them damp before wight is added then they will flatten, granted mine do not have adhesive on them.
What is the humidity where your sander is?
 
Try activating the adhesive with a solvent like xylene, MEK or acetone. You don't want to dissolve the adhesive, merely soften it. After it is pressed into place, use a roller to force the disk into contact with platen.

Tom
 
We switched over to 3M cubitron disks and belts. We had some delam issues as well with other disks. The Cubitron lasts quite a bit longer so you don't have to change disks as often and has great adhesive.
 
i use the green cubitron discs as well, they're made around the corner in a dedicated abrasives shop and everything i buy from them is absolutely top notch.
A few years ago I discussed with the owner why the discs weren't sticking… Same issue, if used every few hours they stick fine but overnight they have a tendency to curl away at the top. He really didn't have any good suggestions for me but I bought a can of Loctite spray adhesive and I just put a few spritzes behind the part where it curls and all is mostly well. They definitely don't stay perfectly stuck but they certainly don't fall off or anything, in fact they are an absolute bitch to change needing lots of heat from the heat gun and scraping.


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I tried self adhesive disks on my 24 inch and my 30 inch disk sanders. I had the problem of the disk coming off but the bigger problem was cleaning the glue residue/film off. So I switched back to master disk cement from freeman manufacturing. The freeman brand is okay but the kindt Collins master cement is better. Kindt Collins got bought out by freeman.

Its a latex contact cement you paint the disk and the platten and you have one shot at getting them lined up but as long as you don't catch the back and peel it off it stays stuck. When you peel it off it comes clean and any cement that does stick to the sander just rubs off. If you mess up putting the disk on just peel it off rub the cement off the disk and start over.

A trick for getting it on clean is to cut a cardboard disk just over half the circle set it against the platten of the sander get the top half of the disk stuck rotate it and slide out the cardboard while sticking the Rest of the disk.

The disk cement takes about 20 minutes to dry before you stick it on and may take a few changes to get the hang of it but the advantages outweigh the downsides.
 
Well I tried to reinstall one of the curled disks this afternoon. I cleaned the platen and used a little 3M Super 77 adhesive. The first attempt was a bust. As I was sliding the disk between the platen and the table I inadvertently touched it against the platen. It was instantly glued for life. I ended up ripping the disk before I could get it removed.

On the second attempt with a new disk I removed the table and reapplied the adhesive to the platen. With a little more breathing room I was able to attach it with no problems. I haven't used the machine yet. I'll check it out tomorrow and hopefully the disk will stay attached. If not I only have 1 more ARC disk. The next batch I buy will be 3M Cubitrons. Depending on the results they may get ordered as early as tomorrow
 
This thread just reminded me why I like belt sanders. :D

So far all is well. The disk is still in place. I do use the 6x48 belt portion of the sander 90+% of the time. The disk is only used for the odd shaped thing that either can't be, or is clumsy to do do with the belt. Hence it is unused for long periods. I do like to keep a disk on the platen for those times when I do want to use it. If I had to install one each time I wanted to use it a 2 minute job would turn into a half hour job.

Half the time the part of the disk that's visible is adhered to the platen. It's just a PITA to start the machine and have the disk fly off or get stuck against the table. Then I have to either attempt to reinstall it, and hope it will stay in place or dig it out and throw it in the trash. In most cases the surface of the disk is still in excellent condition. It just seems like a time consuming waste of time and money to have to dig them out and replace them because the adhesive failed.
 
Have not had this issue with ours and shop gets quite warm in summer.

Peel off off old then clean off old stuff.

Turn on and with wire brush in die grinder hold against platter and give it a go.

Stop to check but do not touch.

Repeat until clean.

Last is hit it with spray adhesive and same stuff on paper.

Be careful as once it touches it is done.

Real bugger to remove

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We use belts for just about anything anymore, but still have a small disc we might use for wood work. I think the humidity is a big factor as south Texas is hot n' humid and we've always fought curling discs. One of our solutions was that we cut a few 3" thick 8" round slices of aluminum bar to store with the discs so they were always kept flat. Storing them in a Rubbermaid tub may help too. I don't remember needing any heavy duty adhesive, but some lacquer thinner in a mister bottle and some general purpose 3M aerosol trim adhesive helped if they didn't want to stick.
 
I tried self adhesive disks on my 24 inch and my 30 inch disk sanders. I had the problem of the disk coming off but the bigger problem was cleaning the glue residue/film off. So I switched back to master disk cement from freeman manufacturing. The freeman brand is okay but the kindt Collins master cement is better. Kindt Collins got bought out by freeman.

Its a latex contact cement you paint the disk and the platten and you have one shot at getting them lined up but as long as you don't catch the back and peel it off it stays stuck. When you peel it off it comes clean and any cement that does stick to the sander just rubs off. If you mess up putting the disk on just peel it off rub the cement off the disk and start over.

A trick for getting it on clean is to cut a cardboard disk just over half the circle set it against the platten of the sander get the top half of the disk stuck rotate it and slide out the cardboard while sticking the Rest of the disk.

The disk cement takes about 20 minutes to dry before you stick it on and may take a few changes to get the hang of it but the advantages outweigh the downsides.

I’ve gotten bad batches of “Apex” discs from even the most reputable vendors. Agreed with all above the better discs, cubitron in green or blue typically stick best, but sometimes you just can’t get them to stick. The cubitrons last long enough I don’t mind spraying the pad and disc LIGHTLY with 3M Super77, but if you’re changing discs regularly the additional time cleaning and prepping for the next pad gets pricey.

Without adding adhesive, my guys will often use a propane plumbers torch to warm up both the disc and sanding pad. Don’t get the disc HOT, just warm... same goes for the sanding pad... just enough warmth to assure the adhesive is nice and sticky.

Also, take a minute to make certain that any personnel using or even near the platen sander has THE RULES!!! ingrained in them

NO GLOVES
NO OIL IN THE QUENCH BUCKET
NO GLOVES, EVER!!!!!!
THE PART STAYS ON THE PLATEN
NO GLOVES
NO GLOVES

I view a 20” disc sander as a crucial tool for the work I do... but I’ve also seen them cripple guys before the dude knew what hit him. In every case the injury was because the guy broke one of those rules. Gloves on, or allowing the platen to get slick and oily or lifting a part off the table. Ask my former employee that now wears a big toe for a thumb.

Skin doesn’t even slow a 20”, 3-horse sander down...

I cannot advise doing so, but a large wedge, such as this one:
3aaaf946dbca4137e6475407856dfffe.jpg

Will immediately stop a disc sander, at least up to 5-horse...

The machine will be irreparably damaged...


Ask me how I know.




Jeremy
 








 
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