We receive many questions regarding deburring of rivet holes. After drilling and installing hundreds of thousands of rivets I can say with some professionalism that you do not need to deburr rivet holes in thin aluminum skin or ribs using a deburring tool that cuts away the metal. What is generally left in the hole is not a burr, but is a hangnail or chips left over from the drilling operation. You can easily remove chips by de-clecoing the parts, use a heavy pair of cotton gloves and lightly run your hand across the drilled sheets. What must be avoided is removing the aluminum from around the edge of the hole. The holes should be crisp and clean, not countersunk from removing material. If you do have an occasional burr (a piece that you cannot remove by rubbing) you can remove it by using a countersink bit and lightly turning it by hand to remove the burr. In non-pressurized aircraft perfectly round holes are not necessary. If you were building a pressurized airplane you should ream every hole and make sure they are perfect to preclude any cracking of skin around the rivet. This is also true in non-pressurized critical structures, as example, a wing spar that may see high loads. But on most parts this is overkill since the structure will not see any pressurization cycles during its service life. Save some time and headache and do not over deburr.