ONX-L01-10: What Drill bit to use for AN5-12A bolts?

[dhogue]

Hello,

I'm now working on installing the Landing Gear leg (ONX-L01-10) shown on plans page ONX-L01(Rev E) View's AA and BB.

The bolt called out is AN5-12A. I measured the bolt Diameter to be .310 in. I tried using a 5/16 in diameter drill (.310 in diameter) but the resulting hole is too large - that is - the bolt is loose/has noticeable play in the hole.

What I am writing to ask those who have completed this part of the build is: What size drill results in a snug fit for the AN5-12A bolt?

As always, thank you for your time, experience and helpful advise.
Don

[Bryan Cotton]

Don,
I can't speak to that size directly, but for critical bolts I generally drill undersize and my last pass is a reamer. For a 1/2" AN bolt I am reaming to something like .4975" IIRC. I mic'ed up a bunch of bolts to guess at the reamer size.

[dhogue]

Thanks Bryan.

Reamers ordered.

[Zack]

This is what I came up with. I labeled the reamers and drill bits (in their baggies) AN3, AN4, etc. I always step up unless I have access to a milling machine with a rigid setup (very rarely).

AN3
Nominal 3/16"
(0.186 - 0.189)
Drill Bit: #13 (0.185)
Reamer: #12 (0.189)

AN4
Nominal 1/4"
(.246 - .249)
Drill Bit: D (0.246)
Reamer: E (0.250)
Reamer: F (0.257)

AN5
Nominal 5/16"
(.309 - .312)
Drill Bit: 5/16 (0.3125)
Reamer: O (0.316)
Reamer: P (0.323)

AN6
Nominal 3/8"
(.371 - .374)
Drill Bit: 3/8 (0.375)
Reamer: V (0.377)
Reamer: W (0.3860)

[dhogue]

Thanks Zack. Very helpful.