Dressing the Rollers on a Wide-Belt Sander

Tips on getting the sander drum true again by running it over flat sandpaper. July 29, 2011

Wide belt sanders - when the front rubber covered roller is still in good shape but begins to sand uneven has anyone ever used a piece of wide belt sander paper mounted to a flat piece of plywood to (sand) true up the front roller so the machine sands even again across the entire roller?

Forum Responses
(Solid Wood Machining Forum)
From contributor L:
That's the standard procedure to true a drum.

From the original questioner:
What grit paper is best to use? Does the piece of plywood the paper is mounted to need to be the entire width of the roller? Mines a 37 inch sander. Or can you just do it "half" like 20" and then the other side of the roller? I have never done it before so I am trying to find someone who has so I can learn what works and what does not.

From contributor M:
We have used the same procedure using 80 grit. A word of caution, there is a lot of friction going on and the possibility of launching the board back at you is great. Very, very light passes. Another option is a longer narrower board that you feed at an angle, so you are still dressing the whole drum but with less resistance than doing the whole width at once.

From contributor D:
We use a plywood base with an apron screwed to the front to counteract throwing tendencies. Full width and no seam in the sandpaper, which should be new. Any uneven wear in an old belt being used will telegraph onto your newly dressed drum. Most sanders have a wheel that is mechanical that is geared very low. It spins rapidly when using motorized up and down control, but you should just turn it by hand for the really tiny movement needed. Lower durometer (softer) rubber drums grab hard, get hot and chatter, so very gradual movements work well.

From contributor G:
Take a board that is the width of the drum, MDF would be best since it will be flat and the same thickness throughout. Take a 6" wide pc of sandpaper and glue it on a diagonal on the board. This way you do not stress the motor and this will keep the board from launching because of friction grab on the drum.