Updrill size for 10/32 bolt

[JFYrineo]

Am going nuts trying to find the right drill size spec for up drilling vertical stabilizer spars for 10/32 bolts. A 3/16” drill is too small, but not sure what/where there may be specs on how tight the hole size is for bolts?

[GordonTurner]

Not at the shop to give you the answer, but google the specs for an bolts, and get the reamer sized to the middle or so of the spec range for diameter. I drill with #15, then final upsize with my reamer, and get a snug fit with most bolts. Sometimes i try a second bolt for a better fit, but its always pretty good.

Gordon

[Bryan Cotton]

That seems odd. Usually the nominal size is a little big, and if you want a really snug fit you drill undersize and ream to the proper size for the bolt. Usually this would be a little less than 3/16".

Are you drilling up in steps? If you go right from a #40 to 3/16, the hole won't be as round as it could be. Holes get a little triangular with a big step. That's another reason to make the last step a reamer for critical joints. Reamers make round holes.