Bolt Edge Distance

[bullojm1]

I know there is a general rule that rivets are supposed to have a edge distance of 2x the diameter. One question I have is what's the rule for bolts? I was in the process of attaching the seat belt anchors to the longeron. I drew where the AN3 (#12) holes were supposed to be, and it was 9/32" from the inboard edge of the longeron, where if I was shooting for 2x diameter, it should be 3/8". Since the longeron is only 3/4" wide, the only way to get the proper edge distance is for the bolts to be smack dab in the middle of the longeron. Here is a pic off of Chad's blog of the part in question:




I looked at a bunch of other builders websites, and they all did it according to the plans, so I gotta wonder is there something I am missing on edge distances? I know I am totally over analyzing this stuff, but any insight would be appreciated!

[svanarts]

I would just trim/adjust the part in question until the holes line up in the middle of the longeron. A few fractions of an inch this way or that on a seat belt anchor should affect things too adversely.

[cjensen]

Mine are moved in ever so slightly to get 1.5D. Remember, it's from the CENTER of the hole, so you only need the width of the fastener between the edge of the hole, and the edge of the material to get 1.5D. 2D is better, of course, but not the "official" rule.

In that particular spot, I think that's part of the reason for there being three bolts. They are close to the edge of the longeron.

[bullojm1]

Chad-

Thanks for your response. I wasn't too concerned about the rigidness of how good the seat belt anchor was held to the longeron as I was concerned about weakening the longeron.

[cjensen]

Yeah, understood. That's why I moved mine towards the middle a bit to get a little over 1.5D.