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Substitute solid rivets?

M

Mich48041

Well Known Member
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Has anyone asked Van's if it is OK to substitute solid AN rivets in stead of the pop rivets? It should be OK for experimental amateur built because solid rivets are stronger, I assume. But what about those of us who intend to register as E-LSA? Can we legally substitute squeezed or driven solid rivets instead of using the blind rivets. I would like to use solid counter-sunk rivets because they can be squeezed perfectly flush. The counter-sunk pop rivets have a rounded top that protrudes above the surface unless the rivet hole is counter-sunk deeper. Doing that results in a hole with larger diameter than the pop rivet head. Or am I doing something wrong?
Joe
 
To qualify for E-LSA the aircraft must be built exactly per the plans.
BTW, are you using the proper dimpling tools? Pulled rivets have a 120* head instead of 100* that are common with driven rivets. Dimpled properly pulled rivets should be as flush as driven ones.
 
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Mich48041 said:
Has anyone asked Van's if it is OK to substitute solid AN rivets in stead of the pop rivets? It should be OK for experimental amateur built because solid rivets are stronger, I assume. But what about those of us who intend to register as E-LSA? Can we legally substitute squeezed or driven solid rivets instead of using the blind rivets. I would like to use solid counter-sunk rivets because they can be squeezed perfectly flush. The counter-sunk pop rivets have a rounded top that protrudes above the surface unless the rivet hole is counter-sunk deeper. Doing that results in a hole with larger diameter than the pop rivet head. Or am I doing something wrong?
Joe
Click to expand...

It is very possible you are doing something wrong, but first your initial question.
If we assume you can qualify for an Amateur Built certificate there are other reasons that solid rivets are not really possible. Many have been discussed here previously but the two primary ones are...

The airplane was specifically designed for construction with blind rivets so the wings and somewhat the empenage, have no provision for accessing the interior to buck rivets.

The other reason is most of the external skins are only .020" thick which is to light of gage for 1/8 rivets. Even the best riveting technique would not look very nice.

As for "machine" countersinking after "dimple" countersinking to make the rivet lay more flush...this is a very bad idea. The style of blind rivet supplied in the kit (CS4-4) is not sharp out on the edge of the rivet head (the head is a little tall as designed). If you machine countersink enough to make it perfectly flush, you have probably compromised the strength of the rivet joint.
 
120 degrees

Mel,
Dimpling is not a problem. It is when I machine counter sink that the pulled rivet heads protrude slightly unless I counter-sink a little bit deeper. Yes, I do use the 120 degree bit as called for in the plans. Maybe I am being too picky. But I do not like to see the counter sunk hole being a larger diameter than the rivet head, even if it is just a 1/64". Thanks for the reply.
Joe
 
Scott,

Scott,
I do not machine counter sink dimpled holes. I only machine counter sink thicker aluminum as called for in the planes. You described perfectly what I was trying to do in my posting when you said, "(CS4-4) is not sharp out on the edge of the rivet head (the head is a little tall as designed)". I should have asked if it is normal and acceptable for the CS4-4 head to stick up slightly. Thanks for your reply.
Joe
 
Mich48041 said:
Scott,
I do not machine counter sink dimpled holes. I only machine counter sink thicker aluminum as called for in the planes. You described perfectly what I was trying to do in my posting when you said, "(CS4-4) is not sharp out on the edge of the rivet head (the head is a little tall as designed)". I should have asked if it is normal and acceptable for the CS4-4 head to stick up slightly. Thanks for your reply.
Joe
Click to expand...

In instances where you have to over machine countersink (enlarge the hole) to make the rivet lay flush, yes it is normal to have it stick up slightly (there is really no choice since it is not correct to enlarge the hole). When dealing with thicker materiel (not lots of that on an RV-12) it is totally acceptable to machine countersink deeper to allow the rivet head to lay flush but as you noticed the counter sink diameter will be slightly bigger than the diameter of the rivet head
 
My experience

If it calls for CS4-4's, you have to make the CS hole larger, or they will be higher than the surface. And yes, that is with the 120 degree CS.

John Bender
 
Roll Bar

The reason that I brought this rivet question up is that I am getting ready to rivet the roll bar and read that the canopy is going to rest on it. I do not want the rivet heads scratching the Plexiglas.
Joe
 
rvbuilder2002 said:
The other reason is most of the external skins are only .020" thick which is to light of gage for 1/8 rivets. Even the best riveting technique would not look very nice.
Click to expand...

Scott,
Could you explain this? In the mid '80s I built a Moni Motorglider with solid flush rivets and it turned out beautifully. The entire aircraft is built from .020" and was designed for CCC-42 rivets. Check out Sport Aviation, May 1986.
 
Mel said:
Scott,
Could you explain this? In the mid '80s I built a Moni Motorglider with solid flush rivets and it turned out beautifully. The entire aircraft is built from .020" and was designed for CCC-42 rivets. Check out Sport Aviation, May 1986.
Click to expand...

Not intending to debate with you Mel, but a personal opinion, is that if this was done by a typical builder it would look like someone had pounded all over the airplane with a hammer.
There is also a specification related to this (though I am unable to find it right now) that recommends maximum rivet diameters relative to what the material thickness is. Consequently, when designing, we are to choose a rivet that matches the material thickness and then designate a rivet pitch within the normal guide lines and for what the load projections are.
 
Mich48041 said:
The reason that I brought this rivet question up is that I am getting ready to rivet the roll bar and read that the canopy is going to rest on it. I do not want the rivet heads scratching the Plexiglas.
Joe
Click to expand...

The canopy rests on the fwd half of the roll bar which I believe is solid AN/MS rivets. The rear window (which by the way is Lexan, only the main canopy is plexy/acrylic) lays over the blind rivets on the aft half of the roll bar.
It would be better to lightly sand off any small rivet protrusion than to excessively enlarge the hole while deeply machine countersinking.
The roll bar parts are more than thick enough to make the solid rivets flush...for teh blind rivets it is close. Just don't over do it.
 
Exactly what I had in mind

Scott,
That is exactly what I had in mind when I asked if I could substitute solid rivets. I wanted to use them on the forward half of the roll bar before closing it up because they fit so much better and look so much nicer. But alas, I have to follow the plans exactly because I intend to register as an E-LSA. The plans call for CS4-4 front and back.
Joe
 
I too was concerned about the canopy resting on the CS-4-4 rivets on the front half of the roll bar. So, before installed them I tested each hole to make sure the rivet sat as flush as possible before I pulled it. Then, before priming and painting, I lightly sanded each one to make sure there was no sharp protrusions. Finished product looks pretty good. We'll see if it works as planned.

Mitch Lock
 
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