[Phil]

I've searched through the Big 3 A&P books and the 43.13, but I can't seem to find an edge distance for bolts in aluminum.

Does a minimum/maximum edge distance exist for a bolt? I know that rivets are 2D min / 4D max, but bolts are never mentioned.

 

[rvbuilder2002]

I've searched through the Big 3 A&P books and the 43.13, but I can't seem to find an edge distance for bolts in aluminum.

Does a minimum/maximum edge distance exist for a bolt? I know that rivets are 2D min / 4D max, but bolts are never mentioned.

Same as rivets...2D minimum.

 

[Phil]

Thanks Scott....

I'm attaching the RV-10 tailcone to the fuselage and I'm asking specifically about the four bolts that are used to attach each forward longeron to the tailcone longeron.

If I allow the proper edge clearance, that moves the washer too close to the fillet on the inside of the angle aluminum. As a result the washer doesn't sit flat because it rides up on the fillet curve.

The only way I can get the washer to lay flat is to move the hole closer to the edge of the aluminum angle. To do that, the edge clearance goes minus 1/32". Assuming I managed to draw the line perfectly straight, that's the best case. I'd guess worst case it could go out by 2/32" (1/16th).

This aluminum angle is 1/8" thick. Does the thickness of the aluminum come into play and allow for marginally cheating the edge distance?

Glad I did this on a mock up first!!

Phil

 

[ChiefPilot]

Thanks Scott....
If I allow the proper edge clearance, that moves the washer too close to the fillet on the inside of the angle aluminum. As a result the washer doesn't sit flat because it rides up on the fillet curve.

I've encountered this a couple of times on my -6A. I simply filed the washer to fit appropriately, reasoning that maintaining edge distance is more important.

 

[rvbuilder2002]

I've encountered this a couple of times on my -6A. I simply filed the washer to fit appropriately, reasoning that maintaining edge distance is more important.

What brad said.
The head of the bolt can be clocked so that it clears the radius. Put a slight radius on the edge of the washers, dab them with a little primer to prevent rust now that the cad plating is compromised, and install.

 

[apkp777]

"Riding the Radius"

You unlicensed builders have discovered all the secret arts of the A&P mechanic. We're keeping bolt edge distance to ourselves. LOL. Look up the edge distance for Hi-Lock or Hi-Shear fasteners. Bolts are the same. It is less than that for a rivet. I actually don't remember exactly what it is.

As said, radius the washer may do it for you, or you make a filler (equal the height of the radius in the fitting) and radius the filler. That'll give you much more room. You'll need a slightly longer bolt of course.

 

[flion]

When putting in washers or fillers with a radius or with an edge trimmed, you may experience the frustration of having the washer spin from the proper clock position. Sometimes it is easy getting your fingers in there to position it and sometimes it isn't. Also, I never liked the idea of torquing the nut and having the washer spin slightly. So, I put a dot of thin CA (the stuff you get from the hobby shop is better than the 'wonder glue' you get at a hardware store) on the washer and use a punch or spare bolt to position it and glue it in place. Just a small dot; unlike resin glues CA works best if there is less. It's a brittle glue and the thicker it is, the less it holds. Also, the longer it takes to set; if you soak a part it may never set well, but squeeze a bit between your fingers and they're instantly stuck... Anyway, it should hold the washer while you torque the fastener. If you remove the fastener, about half the time the washer comes away; if it doesn't, a sharp blow on the edge with a punch will dislodge it.

 

[GAHco]

My understanding..

This is from memory so I would double check of a critical of higher stress area.

1 & 1/2 Diameter from the center of the fastener hole, but I would rather see 2D.

 

[koda2]

2D ED?

I went thru this a couple of months ago and finally found something on an engineering web site. I don't read, write or speak Engineerspeak, but from what I could decipher the minimum distance for aluminum from edge to center of the hole is 2D without loss of bearing strength and the absolute minumum was 1.5D. Tapped holes maybe less?

It sounded like you would have to calculate the bearing forces exerted to know if you were safe going less than 2D.

I thought I saved the reference but now I can't find it. There are plenty of Njunears on this forum; they should know the skinny on this cold .

Dave A.
P.S. If so, there are tons of places on the 6 where there, theoretically, is no margin for error on drilling holes.

 

[Andrew M]

Another trick

is to use a reverse spotfacer. This also will make a perpendicular surface for a fastener to ride if the part is tapered or if the hole is crooked. I see alot of these in castings and extrusions.
Andrew
A&P I.A.

 

[flydjd]

Okay...

is to use a reverse spotfacer. This also will make a perpendicular surface for a fastener to ride if the part is tapered or if the hole is crooked. I see alot of these in castings and extrusions.
Andrew
A&P I.A.

i'll show my ignorance, what is a "reverse spotfacer"

 

[D-Dubya]

It's...

It's kind of like a small milling machine. A small bit makes a flat spot for a fastener, much as you'd use a countersinking tool--but it's flat. This is only good if you have enough material to mill into without weakening the part. Not really applicable for wing ribs or other similar thin aircraft components.

 

[rvbuilder2002]

It's kind of like a small milling machine. A small bit makes a flat spot for a fastener, much as you'd use a countersinking tool--but it's flat. This is only good if you have enough material to mill into without weakening the part. Not really applicable for wing ribs or other similar thin aircraft components.

Even though the longerons do have quite a bit of material, I don't think doing this would be a good idea. It would be cutting a flat into the radius of the inside corner of the angle which would cause a serious stress riser at that point. I think custom fit washers or a spacer with slightly longer bolts is a much better choice.

 

[Phil]

I drilled the holes today and each bolt will require a custom washer to fill the gap. After eye balling it a bit, it doesn't look like too much material will have to be removed from the washers.

I was hoping to have the tailcone joined today, but the plans got derailed when I found the baggage seal at the QB factory was cut too long and ultimately interfered with the tailcone longeron's ability to slide into the forward fuselage. I now have pulled them apart and I'll start trimming that baggage seal down. I'm also going to knock a bit off the tailcone longeron too, since they appear to be a tad longer than they need to be.

I had to quit working on the plane at the end of the Texans / Colts game though. I was way too mad and just seconds from screwing something up. So I tucked her away for another night.

Phil