I spent Monday evening and much of Tuesday evening poring over catalogs, sorting out the details of all the little odds and ends that I need to order. The rest of Tuesday evening was spent fabricating a drill jig for the four holes that go at each corner of the 3 1/8 inch diameter instruments. For the 2 1/4 inch dia instruments, I measured and drilled each hole by hand, which worked, but was very time consuming.
I stole an idea on the RV-List from Jim Oke:
"I made my own template out of a scrap of .040 or so 4130 (could have been 2024, of course).
Draw an X with the legs at 90 degs, then two concentric circles at 1 5/16" and 1 3/4". Drill #40 where all the lines cross - nine holes in total. (The Aircraft Spruce and Spec catalog has a diagram if you need more layout info.)
Lay out your panel marking where the center of each instrument face will lie. Drill #40 at these locations. Cleco the template in place at the center hole, make sure everything is square, then drill the four holes at the small or large circle as needed.
Then set you fly cutter as reqd and cut the instrument cut-out using the center hole as a guide.
Do a few test holes in scrap first to make sure your layout is accurate before you start on your actual panel. :-)
The only change I made was to make the hole in the middle 1/4" diameter, the same size as the drill in my fly cutter. It worked great.
Yesterday evening I spent an amazing amount of time trying to get the fly cutter adjusted to make a hole the right size. I could make holes that were a bit too big, or a bit too small, but I kept missing the happy medium. I must of made a dozen trial runs in scraps of wood or aluminum before I finally got it adjusted.
This morning before going to work I carefully marked where each big instrument should go, and this evening I cut all the holes (except for the attitude indicator and directional gyro, which will go on a removable panel). Pictures sometime this weekend.
This morning before going to work I carefully marked where each big instrument should go, and this evening I cut all the holes (except for the attitude indicator and directional gyro, which will go on a removable panel). Pictures sometime this weekend.