Hatz Biplane Association

I'm ordering a "D" (0.2460) size drill bit for the 1/4" holes. I'm wondering if I'll actually need to ream the steel and if I do, seems like a 1/4" straight shank straight flute chucking reamer will be a bit (no pun intended) too big. What did you use and were you happy with the results? Just looking for a real tight and snug fit on those spar bots.

I did find a "D" reamer, but it's $81 and not sure that'll be required if the hole is already .2460.

I'll be filling the spar holes with sealer before finishing the job, and I guess I have to protect with varnish (or T-88) the wood that will be covered by the steel. I'm also ordering .032 safety wire for bolts requiring that.

Thank you,

John

John,
I bought a .3125 reamer and found it necessary on the 5/16 holes but I did not ream the 1/4 inch holes. I found that after drilling the 1/4 holes through the spars the AN3 bolt was a very tight fit. The spruce must swell a bit after drilling. I will coat the inside of the holes with System Three clear coat and then run the drill through again if needed. I was very pleased that after drilling my spars for the compression struts that they all lined up and fit. This is the most exacting thing I have ever done and it is a true test of patience and precision. I didn't think of it at the time but I would make an extra compression strut base to use as a template when drilling the spars.

Thanks...OK, ordering two STRAIGHT SHANK FLUTE CHUCKING REAMER - SIZE 5/16 along with two "D" bits. Guess I'll pass on the "D" reamer. I'm tempted to give this a try...

UNIBIT #1 drills 13 holes in 1/32" increments from 1/8" through 1/2" and has a shank size of 1/4".