Porter Cable (3 x 21") belt sander throwing belts

[charlessenf]

I got my belt sander out the other day and mounted a 'fresh' belt. Within a few seconds the belt broke and flew off the sander. I kept trying, going through a box of Klingspor belts that, while 'fresh' to me, had been setting on the shelf in the shop for over a year.

THen again, the sander's not a new one either (purchased second hand when my other PC Sander bit soe dust.

Looking at replacement cost, I wondered if anyone knew of a place that repaired such a tool.

Or, if anyone might be able to tell me what to look for or adjust or replace to address te issue before buying a 'really fresh' box of belts to test such adjustments or repairs as might be worth attempting.

 

[Henry W]

Charles - I expect this is about the belts and not the tool. Just do a search here on sanding belts to read about other's experiences.
My expectation is that a new belt would survive where an aged one will not. Buying larger packages of sanding belts that don't get used is often false economy.

I have written here a few times about my experience with a 10+ year old set of 6x48 belts, and my belief that storage conditions may change outcomes. But I recognize that larger belts have larger radii and are easier on the belt than a handheld belt sander might be.

 

[Roy G]

I think the recent belts are made differently than belts in the past. I have a Milwaukee 4x24 belt sander and have belts over 30 years old that work just fine.

Roy G

 

[Melinapex]

Agree with Henry. I have the same PC 3x21 sander and find that new belts don’t age well in the shop. Seems the glue doesn’t hold up so I typically only keep one spare, but usually by the time I get to use it, it’ll self destruct in minutes….. maybe I should keep them in the house……

 

[Martin Roper]

I haven't used my belt sander in years because of belts separating. I've since purchased a Festool Rotex which has an aggressive direct drive feature. Bosch's 6" sander has a similar "Turbo" mode. Discs are also cheaper than belts and dust collection is 1000% better.

 

[Henry W]

Agree with Henry. I have the same PC 3x21 sander and find that new belts don’t age well in the shop. Seems the glue doesn’t hold up so I typically only keep one spare, but usually by the time I get to use it, it’ll self destruct in minutes….. maybe I should keep them in the house……

"...maybe I should keep them in the house…" Yes my experience with sanding belts is that like pharmaceuticals, 'cool dry storage' is best.
Again note that my experience is with 6x48 belts for a floor model belt/disk sander, and not for a hand held tool.

 

[junquecol]

Coleman from Klingspor addressed this many years back at Triangle Wood Workers meeting. The Kelvar strips holding belt together only have about a one year shelf life. At the factory, they keep it in a deep freezer. Older belts used a lap joint at the seam. Grind off the abrasive, add some glue and clamp together. Many older shops had templates for the cutting to size of belt stock, especially if they had a stroke sander, as most stoke sanders were shop made, so no two used the exact length belt.

 

[Oka]

Mine did the same thing. If the bearing on the roller is ok, then typically it is a platen on the bottom. Costs about15 bucks to buy easy to replace.

I replaced that and the belts quit having issues.

There is one other possibility on the roller side (not connected to the motor, that roller has a camber, if it wears flat, then the belts will not track. Never seen that on a hand held sander, have on shop size one though.

 

[zdorsch]

I had the same issue with my delta belt sander. I’m not sure how old the belts were but they were stored in a Midwest conditioned basement before I received them. It was odd because the first belt lasted for several sanding sessions while the rest lasted for a minute or less before splitting at the glue Im joint.

To rule out the machine I went and bought some cheap belts from the box store and I’m still on the first belt from that pack after a few months.

 

[charlessenf]

"a platen on the bottom. Costs about15 bucks to buy easy to replace."

Where'd you buy the platen?

 

[charlessenf]

Thanks all, for the feedback and suggestions.