The bearing edge is the top or bottom edge of the drum shell where the metal hoop mounts the drum skin to the drum shell. Over time, and especially on drum shells made of softer woods, the bearing edges are likely to chip or wear down. This can have an adverse effect on the drum's overall tone and your ability to tune your drum. The amount of damage on the bearing edge determines if the drum shell can be repaired at all. However, in mild cases of wear and tear -- which is usually the case -- damaged edges can be sanded out.
Remove the drum hoops from the top and bottom side of your drum shell. Use a drum key to unscrew the retaining lugs on each hoop.
Use a can of compressed air to blow out the dust and wood chips from inside the drum shell. Dampen a clean wash cloth and wipe down the inside of the shell, and the drum's bearing edges.
Sand out the damaged sections of the bearing edges with a sheet of light, 120-grit sandpaper. Sand in the same direction as the wood grain to avoid further damage to the drum shell. Avoid using heavy-grade sandpaper, and/or a power sander to smooth out the damaged areas of the bearing edges. Using a power sander can result in cracking the drum shell, which is what you want to avoid at all costs.
Be patient. Depending on the amount of visible damage, sanding out chips and scuffs from the bearing edges can take up to a few hours. Take regular breaks and be diligent until the bearing edge is completely smooth. You'll notice a radical change in drum tone and tuning if you do.