I'm cutting the top skin of my forward fuselage for my (OP-43) access panels. I used a step drill to cut near the corners of the first hole and a cutting wheel in a Dremel for the straight edges initially. I then switched to a milling bit with a steel ruler clamped in place to limit the bit and finished with a file. I'm at the point where the straight edges clear the panel by precious few thousandths. My question is, considering that there will eventually be paint on both skin and panel, how many thousandths are adequate? I thought I'd check one of the access panels on my wing where the panel and hole were cut by the factory. I was surprised to see that the gap is much closer than I would have expected, barely more than I've got already. However, the panels I'm cutting will be much more visible and I'm hoping they'll look decent after painting.
Any thoughts?
Any thoughts?