Recommendations for "tight fit" holes

[samiam]

I'm attaching the angles and wing-attach blocks to my preassembled spars. They are already predrilled for bolts - I'm hesitant to just use a hand drill and end up with oblong holes that are not tight fit. Any suggestions from other builders?

[Bryan Cotton]

Mike,
I drilled mine in the drill press. Maybe not the root rib angles but definitely for the spar attach.
viewtopic.php?f=39&t=578&start=560

[radfordc]

I bought a Sonex that had loose wing bolt holes....enough that I could move the wing tip up and down about an 1". I fixed the problem by increasing the size of the hole from 3/8" to 7/16". I updrilled the holes using a hand drill and lots of WD-40 lube. I did the drilling in 1/64" increments....25/64; 13/32; 27/64. For the final 7/16" hole I used a reamer instead of a drill bit. The result was a nice tight fitting hole that required tapping the bolts home with a light mallet.

[Bryan Cotton]

I also used a reamer for my last pass: 0.3725" for the AN6 bolts. There is no slop.

[samiam]

I bought a Sonex that had loose wing bolt holes....enough that I could move the wing tip up and down about an 1". I fixed the problem by increasing the size of the hole from 3/8" to 7/16". I updrilled the holes using a hand drill and lots of WD-40 lube. I did the drilling in 1/64" increments....25/64; 13/32; 27/64. For the final 7/16" hole I used a reamer instead of a drill bit. The result was a nice tight fitting hole that required tapping the bolts home with a light mallet.

I used this 1/64" increment method, and it worked great. Used regular drill bits, but with the small step up each time, the holes came out nice and round.

Thanks for the help!