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James Spangler
03-13-2021, 5:42 PM
Recently I've been using Norton sanding belts for my 3 x 21 belt sander and these belts can be run in either direction, according to the packaging.
This made me wonder about the belts that are one direction only.
Is it a function of how the seam of the belt is joined? In other words, if I were to run a one-direction belt in the wrong direction, is there a danger of the belt flying apart (a safety issue)?
Or, is it because of how the grit is laid down on the belt - sands best in one direction and not the other?
Or something else?

(I have accidently put a one-direction belt on the wrong way and it seemed to work ok and nothing bad happened.)

Thanks in advance for your opinions and expertise.
Jim
Steve Jenkins
03-13-2021, 6:56 PM
Most belts nowadays are taped butt joints and run either direction. They used to make them with a skived lap joint. Those should be run in the proper direction. Many of the taped butt joint belts have a direction arrow but it doesn’t mean much.
johnny means
03-14-2021, 3:46 PM
If you run the belt the wrong direction it adds material to the surface. We do this all the time when our dadoes are a little sloppy. High end wide belts can actually be run in board thickening mode.
Ronald Blue
03-14-2021, 4:48 PM
If you run the belt the wrong direction it adds material to the surface. We do this all the time when our dadoes are a little sloppy. High end wide belts can actually be run in board thickening mode.

Don't you have to run the dust collector in reverse also? This way it's much easier to add material back.
johnny means
03-14-2021, 8:34 PM
Don't you have to run the dust collector in reverse also? This way it's much easier to add material back.

Sometimes, but our dust collection is poor enough that the ambient air provides plenty of material for all but the most aggressive board thickening.
James Spangler
03-14-2021, 10:14 PM
Ok guys, have your fun at my expense, I can take it. ;)
I was mainly concerned if I was causing a safety problem if I try to run a belt backwards.
So far, I have one opinion that as long as the ends are butted together, I can do it.
Ron Selzer
03-19-2021, 7:11 PM
years ago belts were lapped together at the splice and there was a slight bump. those belts needed to be run one direction only
newer belts are butted together and not very often do you see direction arrows on them
Ron