What am I doing wrong with this Porter Cable belt sander?

[Alan Lightstone]

I have a Porter Cable belt sander that I haven't used for at least 10 years. The sanding belts are all at least 10 years old.

I actually had a need to use it recently, on 3/4" plywood (don't ask), and every time I started sanding, each belt would break in roughly 30 seconds. I had a failure rate of 100%.

I checked the tracking each time, and the sandpaper didn't go off one side or another, it was just when sanding they would break.

Is it just that the adhesive on the tape on the belts had gone bad after 10 years, or is there something else I'm doing wrong? I literally blew through 10 belts in no time at all.

[Ole Anderson]

Belts sought to have an expiration date. Adhesive is the problem.

[Jim Matthews]

Unplugged, do both rollers turn?

[Jim Becker]

There was another thread not long ago about a similar situation and what Ole said was also the conclusion there, if I'm not mistaken. I haven't used my Bosch 3x21 in many years and I bet the belts I have are also toast due to age...

[Tom M King]

Belts are just too old. I've had whole boxes do the same thing. It doesn't help when uses are 20 years apart.

[Rob Sack]

Are the belts breaking at the seams? According to the 3M rep, the belts for my wide belt sander should not be used after about a year as the seams can fail.

[Lee Schierer]

I had a similar problem with my Porter Cable belt sander. I was able to significantly reduce the breakage by inserting a spacer under the home position of the tensioning slide. The spacer reduces the tension slightly on the belt and I break far less, even with older belts. This is a fuzzy photo but you can see the aluminum shim that holds back some of the spring tension.
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The shim is held in with some double sided tape.

[Al Launier]

Clever Lee, where there's a will there's a way!

[Frank Pratt]

I bet I've read at least a dozen threads on this very subject. Personally, I've never had a belt break at the seam & right now I'm working on a batch of belts that are close to 10 years old. I'll probably get bit any day now.

[Dave Cav]

As discussed, they are old and need to be replaced. I took over a school wood shop where one of the previous teachers purchased nearly a lifetime supply of portable belt sanding belts, dozens of them. I had to throw all of them away (although we did use some of the finer grits for conventional sandpaper). I did a lot of googling and asking around, and some experimenting, and was never able to come up with a satisfactory way to reglue them.

[Justin Rapp]

I've had the same issue with old belts. Grab some fresh belts and you should be in good shape. It's a much cheaper option to test the sander to make sure it's working well that trying to fix a non-broken tool.

[Sam Puhalovich]

I'll try this with my Makita.
I 'sharpened-up' Lee Schierer's photo.
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[Alan Lightstone]

Are the belts breaking at the seams? According to the 3M rep, the belts for my wide belt sander should not be used after about a year as the seams can fail.

Yes. All broke at the seams. Two different brands of belts.

[Dave Cav]

Good info here:

https://abrasiveresource.blogspot.com/2015/10/making-your-own-abrasive-belts.html

I do recall that one vendor I buy wide belts from specifically mentions the cure time and suggests that the splice will cure while in the shipping process.