Finally starting on the Wings! Not sure where all the time has gone but stuff like taxes, replacing the water heater, and couple trips out to Idaho seem to be part of it. I spent a lot of time reviewing the plans, drawings, and other builder logs to figure out how to mount all the plate nuts on the spars. I decided to do the drilling for both the tank nut plates and the access plate nut plates at the same time. The plans have you do one set at time, but given the set up work that is common to both, I decided to combine the tasks. The spars are certainly high value parts you wouldn’t want to screw it up. I taped up some of the spar assembly seams to keep the drilling chips out as others have done.
To start, I clamped the left spar to the table bottom side up. My process is: 1) drill out #40 the rivet holes for the plate nuts for the tank and W822 access plates. 2) Cleco on a sacrificial backing plate to support the wing tank plate nut counter sinking for the #8 screws. 3) Drill out #30 holes for each countersink in the spar and backing plate. 4) Countersink with the #30 to 0.365” diameter for the Tank plate nuts and 0.306” for the access plate nuts. 5) Countersink each rivet hole #40. 6) Check each countersink for size with screw or rivet as appropriate. 7)Debur.
Some notes. There are three W822 access plates that require 4 plate nuts each (on the bottom side of the spar only). The hole patterns in the spar help you identify them. The backing plate will center the countersink as you progress through the spar material. Without it, the #30 countersink bit will wander/chatter once the bit starts coming out the other side of the flange. The 0.365” dia finished countersink diameter is from VAF forum advice. Tonight I got through drilling all of the rivet holes and most of tank nut plate counter sinking.
Drilling in the dark
Old rudder TE angle used as backing for countersiniking
