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"deburred" too deep

RV7AJeremy

Well Known Member
So I have my father in town helping me with the project. I showed him how to deburr then I got distracted and stepped away for a few minutes. When I came back, I saw just how far the deburring bit went into the material. The material just so happens to be my longeron!!!! About half of the holes, from about the midway point aft, are countersunk enough that a NAS rivet sits flush. I am going to email vans in the morning but what is the consensus from the group? I am a little nervous.....and not very happy with myself to not watch over him for a few.:mad:

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Jeremy, Aren't they supposed to sit flush? The one rivet in the picture looks fine by me. What am I missing? -Jim Edit: Oh yeah, you said debur...not countersink. I think I'd just use AN426's and press on.
 
possible fixes

Just for clarification, this is the backside of the longeron, the front is countersunk to accommodate an AN426AD3 rivet.

I think I may have options:
1. Drill out to accept an NAS1097AD4 rivet

2. Drill out and re countersink and dimple for an AN426AD4 rivet

3. If vans gives me the go ahead just use an AN426AD3 rivet (might need a slightly longer length).

Thoughts anyone?
 
If you use a little longer rivet you will have just made a double flush joint.

It should have essentially the same strength as the plan joint - I bet Van says go ahead, but let us know the factory recommendations...
 
BTW, related to father's helping out. I was showing mine how the DRDT-2 works on some scrap. You know, drill a couple holes, show him how it makes dimples. He takes control with the scrap and I walk away. A few minutes later I go to use it and it just doesn't feel right. Seems that it just won't squeeze enough. Did you guess it? Sure enough, he practiced dimpling a couple more times where there was no hole. The male dimple die just punched right through. Yes, it took a little while to drill out the aluminum that was pressed into the female die. Best to you, -Jim
 
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I think you already have the answers.
As to deburring, I almost always used the hand deburring set.
Especially if you try to keep someone busy who might not be up to speed on everything. The light weight tool in your hand vs. the heavier powertool
and the time gained is very minimal and you will not over deburr.
For me, it was always a good time to reflect on the project while twisting away on the deburring tool.YMMV;)
 
I don't know if he still does, but bob sold that same tool years ago, i bought mine from him when I started my kit in the dark ages.

bob burns
N82RB RV-4
 
I don't know if he still does, but bob sold that same tool years ago, i bought mine from him when I started my kit in the dark ages.

bob burns
N82RB RV-4

Yes, I built an airplane with that tool and I bought it from Avery. Can I just say, though, that $35 for that is ridiculous? I think it's got about $3 worth of material in it.
 
Vans Response

From Gus at Vans:

I would simply rivet as normal - the only effect will be that the rivet will sit
partially in the small countersink. So it will be similar to a double flush rivet,
but not quite flush on the inside. The shop head will fill the countersink and
then over and around it. You may need a slightly longer rivet, but I would try
it first with the stock length. Unless the head is very undersize it won't matter
(ref Section 5D).
 
Looks like the answer was given before contacting Vans!

I never heard of a "double flush rivet."
(note: I did not build my 6A so that may explain my ignorance on this subject only)

Sounds like "double secret probation."
 
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Looks like the answer was given before contacting Vans!

I never heard of a "double flush rivet."

Sounds like "double secret probation."

On an A-model, there is only one spot where double-flush rivets are necessary. The most outboard four or five rivets (I forget; it's been a long time and the mind blocks out trauma) on each side of the main spar to center skin rivets, and where the main gear weldments eventually need to sit.
 
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