Brief Description: Tank attach platenuts and screw holes
Completed drilling and deburring platenut attach holes and srew holes in flanges of both spars. Preparing to countersink screw holes using #19 counter sink. Instructions say to rivet on platenuts and use them to guide a #30 counte rsink. Test on scap for #8 screw shows that the counter sink must go completely through the material and then some to be deep enough to allow for a flush fit of #8 screw head. This will require a guide on the back side of the spar flang to keep the counter sink blade from wondering and forming an oblong hole. Choice is to follow instructions, riveting on platenuts first and using them as the guidle or making a guide from angle that can be clamp to the inside of the spar flang. I'll make the decision at the next work session.
