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Riveting Problem

D

D&M Dan

Well Known Member
Well I riveted the R side of the HS skin. All went well until I noticed all rivets done on the main spar have distorted the skin. Ribs and squezzed rivets are fine. Is it possible I did not coutersink deep enough? I made a test piece of dimpled skin and checked to make sure it was sitting flat on the spar when countersinking. Or is it possible my gun operator is doing something wrong? I would think riveting on the thicker spar material should go easier. :mad:
http://img148.imageshack.us/img148/816/img00438sf.jpg
 
I concurr

Yep thats what it looks like. :eek:

Practice withe some scraps of the same gauges of aluminum before you start again. I did that until I got all the depths just right.

In th .032 you can Countersink, but be very careful and keep your c/s clean and steady. Once again practice on some scrap, or your real pieces may just end up that, scrap.

Have fun, you'll get it.
 
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Did you rivet the ribs to the spar and skin first and then go back and put rivets in the holes on the spar that are in between the ribs? This can cause wrinkles. You want to start riveting at the center of the skin and work your way out to each end.
 
I don't remember any countersinks under any skins on my HS...what model are you building?
 
G-force said:
I don't remember any countersinks under any skins on my HS...what model are you building?
Click to expand...
They are 0.032 thick, in theory they could be countersinked... I didn't countersink any as they can be just dimpled and they will be much stronger after that. And dimpling is also much easier process IMHO.
 
I noticed that the dimples started getting shallow on my spar and after investigation I found that my pneumatic squeezer was ( with adjustable set)
was backing off. What caused this...I dont know..but I keep a close eye on the depth now (and re-adjust as needed)...I dont know if this caused your wrinkling, but something to look out for if your using the same set up.
Jim
 
I am building a 9. Instructions say to countersink spar. All web sites I have seen they have countersunk. After the nose ribs were installed I followed instruction to begin riveting spar. Should I start at the center of the spar and work my way out? How deep on the countersinks? I had these set up to receive my test piece sitting flat. Should it be deeper for rivet expansion?
 
Dimpling

D&M Dan said:
I am building a 9. Instructions say to countersink spar. All web sites I have seen they have countersunk. After the nose ribs were installed I followed instruction to begin riveting spar. Should I start at the center of the spar and work my way out? How deep on the countersinks? I had these set up to receive my test piece sitting flat. Should it be deeper for rivet expansion?
Click to expand...


I'm also building a 9. I countersank my HS spar, too. Since then, I bought the DRDT-2 dimpler, and all of my spars since have been dimpled. The DRDT-2 works great for dimpling spars, and they come out much nicer.

At this point, my opinion is that you should drill out the skin rivets, order a new skin from Vans (if necessary) and redo it. I realize that's a lot of work, but if you don't, you will look at that HS for years to come and wish that you had.
 
D&M Dan said:
Well I riveted the R side of the HS skin. All went well until I noticed all rivets done on the main spar have distorted the skin. Ribs and squezzed rivets are fine. Is it possible I did not coutersink deep enough? I made a test piece of dimpled skin and checked to make sure it was sitting flat on the spar when countersinking. Or is it possible my gun operator is doing something wrong? I would think riveting on the thicker spar material should go easier. :mad:
http://img148.imageshack.us/img148/816/img00438sf.jpg
Click to expand...


Take a picture of the INSIDE of the HS and post it here. The outside is just a symptom. The actual interface between the skin and the spar on the inside will almost certainly show exactly what the problem is.
 
Countersink to deep??

Hmmm... any chance the countersinks in the spar flange are too deep? On some of my early countersinks I had a dimpled test piece, and kept countersinking my spar until the test piece fit completely flush against the flange. Then as I felt it slip slightly I realized the dimple could almost swim around in the hole. This could also happen if your test piece is a thicker material than the skin you'll be riveting.
 
I don't think I went too deep as I checked each one with a dimpled test section of light material. If you look at the picture we had one rivet we forgot to set. On the outside of the skin you can see it is up slightly, almost like somehow the skin is shifted and the dimples are not sitting squarely in the countersinks. I don't know how this could happen except to say I started riveting the spar from the outside inward.
 
D&M Dan said:
I don't know how this could happen except to say I started riveting the spar from the outside inward.
Click to expand...

If you started from the outside of both ends of the spar and worked your way inward, that is probably the problem. As you start to rivet and the skin tightens to the spar, it slightly shifts from the way it was positioned when it was held to the spar with clecos. As you get to the center, with both ends firmly riveted, there is no place for the "shifted skin material" to go, so it starts to buckle and you get wrinkles. If you start from the center and work your way outward, the extra material moves outward and the skin continues to lie flat as it is riveted. If you start to rivet at one end of the skin and work your way all the way to the opposite end, you will probably be OK, but all the videos and books I've seen on this subject suggest starting in the middle and working outward.
 
I don't buy that... I mean, these kits are produced with such tolerances, that it really won't do that unless the pre-punch holes were mis-aligned. I'm assuming everthing lined when you were match-drilling it? And you CS'd the spars? More detailed shots would help, but something else is happening here IMHO. I also thing that Dimpling the spars works better, thats how I did my -7...

Is it possible that you CS cutter isn't the correct (100??) angle?
 
Yes... but...

osxuser said:
I don't buy that... I mean, these kits are produced with such tolerances, that it really won't do that unless the pre-punch holes were mis-aligned. I'm assuming everthing lined when you were match-drilling it? And you CS'd the spars? More detailed shots would help, but something else is happening here IMHO. I also thing that Dimpling the spars works better, thats how I did my -7...

Is it possible that you CS cutter isn't the correct (100??) angle?
Click to expand...

Even if Vans tolerances are good.....

If you countersink in 0.032 for a -3 rivet, you get a "knife edge" condition according to the Mil-Spec.

The FAA allows this (in AC 43.13), but the Mil-Spec quotes 0.040 as minimum for countersinking for -3 rivets.

Because of this knife edge, it is quite plausible that the hole in the skin and the c/s hole can misalign even before riveting.

I also recommend dimpling to everyone, then the two holes will "self-align" when clecoed together... also you don't have to worry how deep to countersink... :)

gil in Tucson

UPDATE

If you check out this MS20426 specification

http://www.barnhillbolt.com/specs/SolidRivetMS20426.htm

You can see that the -3 rivet head (dimension B on the drawing) is actually 0.036 deep -- clearly leaving no "meat" remaining in a #40 hole in a 0.032 sheet, and even enlarging the hole somewhat.... not helping the alignment.
 
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I don't know how thick the HS spars are on other RV models but on my 9A they are 0.063". That's the same as the main wing spar. Plenty of meat for countersinking and according to Van's, too thick to dimple.

To make sure your countersinks are ok, make them no larger than the countersink on the female dimple die, and at least 2 clicks larger than needed to hold a rivet flush.
 
How thick?

ronoc74 said:
I don't know how thick the HS spars are on other RV models but on my 9A they are 0.063". That's the same as the main wing spar. Plenty of meat for countersinking and according to Van's, too thick to dimple.
.......
Click to expand...

They are 0.032 on the RV-6s ... which model are we talking about here?

gil in Tucson
 
This is a PERFECT spot for an EAA Tech Counselor to give you the exact answer in a fraction of the time you'll be able to get here -- and with more certainty (nothing against VAF, of course, but it's very difficult to diagnose this one online). Do you have a local chapter? Where are you located?
 
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