Flap control rod holes in six fuselage quandary

Been avoiding the task of cutting the flap control rod holes in fuselage. A little job but one of those jobs like pro-sealing, making "the big cut" etc. to me mainly because I took a bunch of photos at Osh of other people's attempts and the variation were very surprising. Some were what I would call perfect with just enough area in a special shaped hole to allow for proper operation while others almost looked like a hacked in escape hole. Does anyone have any tips on hole locating and shape rather than doing a trial & error method. Since it's a six I'm assuming no two are alike in this world of " pre-pre punched".

Start slowly and expand the holes a little at a time is about the best I can offer. I started with small holes and enlarged as necessary. I hated cutting those holes in my "pristine" fuselage.

You are right about no two being the same in the non pre-punched world. And, even the pre-punched guys sometimes have to open up the hole to eliminate interference between the flap link and the skin.

Start with cutting the hole in the bottom/side of the fuselage to allow the rod end into the fuselage with the flap in the up position. Once this is done, the rod end can be connected to the flap link (flaps in up position). Lower the flaps and open up the hole where the flap link hits the skin. Keep working this way until the flaps can be fully lowered. Once the minimum sized hole is done to allow full flap up/down motion, open the hole to add clearance between the link and the fuselage skin. You should end up with a hole that looks like it is supposed to be there, not an "escape hatch".

Thanks for the advice. I guess I was hoping for a magic tip. Like all else in the non pre-punched world, everything is done in baby steps.

Run a Unibit up through it to open it up initially, then work to final size with a Dremel or die grinder. For the finishing touch you can buff the edges out with a little scotchbrite wheel on a Dremel.

That first hole

It's that very first hole that that I hope will be in the ball park. Some of the larger examples I've inspected seem to stem from a misaligned primary hole.
If I could just get Superman to stop in some day with his X-Ray eyes it would be a breeze.

Another suggestion. Make a third link (a throw away) so you can leave it attached to the flap and control mechanism and enlarge the hole with the dremel only as needed without removing the link (rod) each time. Of course the removal of metal is when the flap is extended. I have a marred up one at the hanger that I loan out to the local folks. It works great because you can remove only the metal needed without guessing. That is after you create the initial hole. Leave the motor disconnected so the flap can be pushed up and down manually as you make adjustments.

Larry

Here's the basic shape that worked for me on a -9A. Do one side to your liking, then make a paper template for the other side. The link moves both in and out, and forward and back through its travel, so the half moon seemed to work best.