Brief Description: Machine countersinking the trim tab hinge spar.
The top part of the spar that will support the trim tab countersink needs to be countersunk since this part will be sandwitched between the hinge and the dimpled skin.
To give the holes good support while countersinking, I drilled a series of matching holes in a piece of wood and clamped it in place with a few clekos so it could be evenly drilled while holding the countersink bit in place. I use this same method way back when drilling the rudder trailing edge wedge. I used the countersink cage bit holder on the drill to get an even depth. Just to test the depth of the countersinks, I made a little test form out of scrap and dimpled it. Then I was sure I had the depth correct when there was no space between the spar and the dimpled piece.
Using drilled wood to get a nice even countersunk row.
My testing jig to make sure I had the depth corret for the countersinks.
