I started off by looking closley at the plans and marking the orientaition of the spars.
After looking at some other builders sites I deceided to build a jig to countersink the #8 screw holes. From what I have read it give something for the countersink to ride in preventing oblong holes. I drilled out the #8 holes with a 19 bit and then used the #19 countersink on the holes.....The jig worked out great.....cleco it on, then use some side clamps to hold the jig on, remove clecos and then countersink. I read on other build logs that a measurement of.370 was a good countersink diameter.
Clamping up the spar getting ready to start the countersinking process
