Brief Description: Countersink of Wing Spar: Fuel Tank Skin Platenuts
Overall a great night for building. Temp was nice and cool with lots of fog and mist. Low ceiling prevented any fliight lessons tonight so we settled in to figure out the countersink process for the Wing Spar. Specifically, the plate-nuts to attach the access plates and the fuel tank skins.
Jeremy assisted this time. His help was invaluable in figuring out the directions and we discussed each point to ensure that we would not screw up this valuable Spar. Later in the evening Katie dropped by to keep us company. She worked on her homework while we figured this thing out.
Of primary importance was building a backing plate to allow the countersink bit to follow. We ended up using a piece of 1/16" aluminim angle from Loews. Another builder on this site used 1/8", would work even better, but we are extremely happy with the results.
Also to determine were drill sizes. We ended up drilling the rivet holes with a number 40 drill, and the center-screw hole to number 21. So far we've countersunk just the rivet holes on one side of the left spar. Still to do are the center holes. After having adjusted the micro-stop for the #40 size, I think we'll continue on this path and then go back for the center-holes following this.
BTW, we searched the drawings high and low looking for spare-flange #806, only to find out on the RV-8 the part number is #806 and the RV-7 part number is #706. Everyone else probably knows that...but I didn't.
Will pick this up again on Saturday. We have an airport open house that day.
