Date:Jul. 14, 2018


Brief Description:

The HS skins are already dimpled so match drilling is not going to happen.  I final drilled the rear spar holes with a #40 bit and then countersunk to the proper .007″ deeper than the standard countersink for a rivet being flush with the face of the material.  This takes the face of the countersink (maximum width of the opening) from .0176″ wide to .0193″ wide.  I also deburred and trimmed the REPLACEMENT HS-1013 front spar cap, HS-1014 stab stringer, and HS-1015 stab stringers per the plans.  I find that it is best to apply light pressure to the countersink while just getting started then gradually apply more pressure.  This keeps the pilot from acting like a drill bit and smashing a larger oval shaped hole into the material.

Scrap aluminum used to guide pilot of countersink after match drilling.  This material will guide the countersink pilot and keep it from wallowing out the thin material it is countersinking.  Thanks Eric from Vans support for the tip.