I have not used my 4" belt sander a lot over the years but have bought different brands of belts a number of times. I just received 3 80 grit belts with directional arrows on the inside of the belt. I have never seen this before. Am I missing something?
OK, next dumb question. Could all the other belts I have bought been put on running in either direction? The reason I ask is because some older belts, maybe 10 years old, have been coming apart at the seam. I just figured it is because the adhesive has failed due to age. I have run them with the seam angled in the direction of rotation and opposite the direction of rotation and it has not made a differernce. These belts are a good quality from a company we all know.
I've had the adhesive fail due to age, even on brand new belts that have sat on my shelf for too many years. So now I don't buy more than I need at the time. The ones that do fail make good material for your sanding blocks!
Most belts are bi directional, so how you put them on usually is not the issue. Most of the time, moisture and bad storage cause issues.
One thing I have noticed if they get bent or twisted in storage the edge will catch on the machine and Boom ! the belt comes apart.