Van's RV-9A in Aurora

The Big Picture

The Big Picture
Flying! 8/28/2011

Sunday, September 28, 2008

3 hrs.
Made up countersink guides using a scrap piece of aluminum cut from the angle used for the HS (the very first bit of cutting on the HS). Drilled a #30, and then two #40's to make a simple jig. Used 2 AD4263-4.5 rivets as guides to align on the spar, then clamped it in place. Then used the #30 countersink to cut the holes for the screws. Did all of the #6 holes this way, both spars.

Did one side of one spar with the same jig. Then made another using a #27 hole and the #6 platenut jig to get the holes lined up perfectly. Of course used the #6 countersink cutter, which works great with this jig on the #8 screws. About 3/4 of the way done countersinking one spar. Very happy with the quality of results. Very little chattering, and perfectly smooth countersinks. Used Boelube to help the cutter out. Just rubbed the stick over the holes which shaves off a bit of the lube.

Setup for this method takes a little bit of time. Thought about making a jig with 3 or 4 locations to do several countersinks at once. This might work for the access plate #6 countersinks. But it seems that the number 8's have variable spacing, so a multihole jig just won't work. Oh well, one at a time gives the cutter a chance to cool, and the compressor a chance to catch up (neither one seems to be a constraint, but it's good to have some margin).