SonexBuilders.net

I have a concern I thought I 'd throw it out there for some advice. I've drilled my B Model wing attach blocks up to 1/2" as prescribed on the drawings. The holes are straight and snug. Not hammer tight though...I can push them in with my hand....definitely not loose (I hate the thought of having to put the 1/2 bit through them again at rigging).

I'm more concerned about the 3/16 block mounting holes. A few of these holes are not "tight fit" meaning I can insert the bolt with little effort. They're not sloppy by any means...just requires no force.

I guess I'm not quite sure what is acceptable...

any thoughts or advice appreciated...

peter h
SNB0021

Are you talking about the three holes where the wings overlap in the center? Those are only for rigging the wings. They need to be just tight enough to keep the wings from moving relative to each other while you drill the wings to the fuselage. A few people have used bolts in those three holes instead of rigging pins so that may be an option if there is only a little slop in the holes. Another option is to make the holes a little bigger with a reamer and make rigging pins out of 5mm round stock instead of 3/16.

For the 1/2" holes some have put 7/16 drill bushings in the wing blocks and drilled the fuselage angle pieces to that diameter and then reamed to 1/2" after removing the wings. If don't want to use drill bushings and do drill through the blocks again and they get a little messed up you could also ream the whole assembly and up the hole size to fit a 14mm bolt.

Keith
#554

kmacht wrote:Are you talking about the three holes where the wings overlap in the center?

No, the holes I refer to are the 3/16 holes in the attach blocks, ie the holes used to mount the blocks to the spars. The call out is for these to be "tight fit". Several of my 3/16 holes are not "tight fit"..not a bad fit, certainly not sloppy, just not a "tight fit" as per the definition.

thanks,

peter

Check different bolts with a micrometer as the cad plating on bolts can vary as much as .003. You'll be surprised how the sizes vary on different AN bolts.
You'll more than likely find bolts that are tighter than those you're testing with now, but as long as there's no slop, an 'easy-fit' bolt torqued properly is perfectly acceptable.