Access Holes

[bjohnson]

Scott, In regards to cutting the access holes in the skins, I had purchased some time ago a fly type cutter from (Canadian Tire) of all places. This tool has a pilot drill with a 3/16 square H.S.S. tool bit mounted in an adjustable arm. It can be adjusted from about a 1" dia. to about 4" dia. With the skin being supported (wood back-up) and held down securely, I have had great success. The secret is (1) to grind the proper clearance angles on the tool bit, (2) Use a variable speed drill and let it "float" as the tool bit touches the skin, (3) Do not let the tool bit cut all the way through all the way around. Once it starts breaking through it will try to grab. This is where the variable speed help to control. Ideally , it works best if you can cut approx. half way through from each side. I have done my wing skins, tank skins and bottom skin strut doublers, After removing the center slug (they may make nice washers some day) a quick run around with the deburring tool leaves a perfect hole.-Hope this helps-Bob J.