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Those 3/16 big rivets :-((

Ian

Ian

Member
Does anybody know the right way for setting of those big 3/16 rivets on the wing spar..........hammering seems to be a little bit brutal.........what about 6000# tandem cylinder squeezer; is there a special yoke available capable of both gap # reach for spar flange and laminated and that would be rigid enough to avoid any shifting of rivet shank when squeezing ?................

This is really a messy job on the -3 !.......I wish I had a pre-built wing !.......Don't want to fold it inflight !....
 
Van's used to have a squeezer that they loaned out for just this purpose. Check with them.
Mel...DAR
 
big rivets

A 3X rivet gun with an appropriate set and large bucking bar (the size of a small dumbell) work well.
 
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A friend built up the spars for his RV-6. He made a fixture for holding the rivet sets, then struck it with a large hammer. He said it worked real well. He said, before he started, he thought he would be removing a few bad rivets, but he got the hang of it right away and didn't mess up any of them.
You need to keep the number of times the rivet is struck minimal. They work harden after only a few hits.

Bob S
 
I built my 4 spar with the trusty c-frame and a BFH (big f***ing hammer). I had to make a piece of steel angle to support the base of the c-frame, but it worked perfectly.
 
Thousands of RV spars have been built with a C-frame and a large hammer, as others have mentioned. It is not difficult, works well and does not require expensive equipment. Think of it as a very slow speed rivet gun.
 
Slow yes, but really not bad. Just put on some headphones and start pounding away. I did mine on the garage floor so that the workbench wouldn't soak up my hammering. The whole thing was actually kind of relaxing.
 
A Riveting Experience

Ian said:
Does anybody know the right way for setting of those big 3/16 rivets on the wing spar..........hammering seems to be a little bit brutal.........what about 6000# tandem cylinder squeezer; is there a special yoke available capable of both gap # reach for spar flange and laminated and that would be rigid enough to avoid any shifting of rivet shank when squeezing ?................

This is really a messy job on the -3 !.......I wish I had a pre-built wing !.......Don't want to fold it inflight !....
Click to expand...

Take heart. Soon, you'll know the uncommon satisfaction that YOU assembled the very heart of the airframe...the main spar.
mainspar1158ea.jpg
mainspar2153oc.jpg

I agree about the hammering. This crude if usually effective technique must work. I've never heard of this general spar design failing yet. However, it does point to the list of reasons I would be less critical doing a prebuy inspection on the average certificated spam-can than somebody's homebuilt put together with good intentions and Neanderthal finesse.

Actually, 3/16 rivets can be set almost as easily as 3/32 rivets....with the right equipment. Given a choice, I almost always prefer to squeeze rivets as opposed to shooting them. However, a 4X rivet gun mated to a substantial bucking bar will make short professional work of the job. A 3X gun "can" work on many of the spar rivets but tends to work harden a given rivet if not set quickly enough. I can't imagine a 3X working acceptably on some of the longer length 3/16 rivets on the -6 series spar. I'd be willing to loan you my 4X gun and a 3/16 rivet go/no go gauge for $20 AND shipping costs, but must insist on a $300 deposit. Surely someone in your area has one to borrow. At one time, Van's had a pneumatic squeezer fitted with the suitable yoke available to loan on a first come first serve basis to accomplish the same thing. I'd try that route first.

Rick Galati RV-6A "Darla"
 
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Rick6a said:
I agree about the hammering. This crude if usually effective technique must work. I've never heard of this general spar design failing yet.

Rick Galati RV-6A "Darla"
Click to expand...

However if you miss with the hammer and strike the spar you put a stress riser in spar which could start a crack! I have put some heavy duty repairs on 737's for gouges like that. Just look at the chalks accident who thought a little drill hole could take off a whole wing. The Rv fleet is still pretty youg so It will take a while for faults to devlop if they do.
 
Ok, I think there is some misunderstanding about the hammering thing. First of all, you don't hammer the rivets, you hammer the top of the c-frame tool. This thing is designed for this very purpose and works very well. You put the tool on the floor, clamp the spar pieces together, arrange some supports on either side of the tool, and start swinging. A heavy hammer will only require a couple of whacks per rivet, so work hardening is not a concern. As far as missing goes, I can't really imagine missing the tool and hitting the spar, but I guess anything is possible. Personally, I think you have more chance of dinging things if you use a 4X gun. A squeezer would probably be the best method, but the c-frame works just fine. The original poster was asking about the "correct" method. My manual said to use the c-frame, so I did. If you haven't tried it, you'll never know.

Steve "Flintstone" Zicree
RV4 finishing
 
flip the spar

The only thing I would add here is that I found myself flipping over the spar so that the thick parts of the flange were on TOP of the thin parts. This seemed to prevent the splaying of the splices in the spar.

To check this, look down the edge of the spar after you set a rivet. The splices should be tight. If you can see the body of the rivet, that's not good.

Now, Van has said that it is ok. The Mil-Spec says it is not. I went with the Mil-Spec.

In one of those ironic twists: I built my own spars. But the RV-4 that I bought ( built in the mid '80s) has Phlogiston spars. Go figure :).

John
 
I plan on folowing a cobination of 43-13, Mil Spec, Cessna and Boeing manuals :p . All aircraft grade hardware. I am going for the trophys!
 
I plan on folowing a cobination of 43-13, Mil Spec, Cessna and Boeing manuals :p . All aircraft grade hardware. I am going for the trophys! If you want to talk about hard rivets to buck try 3/16 or 1/4 D rivets. I have the surgerys to prove it.
 
Broken-wrench said:
I plan on folowing a cobination of 43-13, Mil Spec, Cessna and Boeing manuals :p . All aircraft grade hardware. I am going for the trophys! If you want to talk about hard rivets to buck try 3/16 or 1/4 D rivets. I have the surgerys to prove it.
Click to expand...

Comparing war stories.... AD6 (3/16") rivets were quite the norm at McBoeing, where I pounded rivets into F-15's and F-18's for a living. Specially cushioned half-gloves were available (but hardly used) for the person on the bucking end of the rivet. Teensie AD3's were occasionally called out but mostly AD4 and AD5 rivets were used to attach electrical clips and such to structure. I will say this though. When it came time to shoot those rare but obscene 1/4 D rivets which were only used as a repair for really botched up oversize holes, you had to check out a 6X rivet gun (called the Hog Leg) and wear headsets over your ear plugs. Usually, your helper would disappear. :D

Rick Galati RV-6A "Darla"
 
sparrivettooling9fp.jpg
Here is what my setup looked like for setting the spar rivets. The partially hidden block under the spar was a piece of steel with a hole that held the cupped rivet set for the formed rivet head. The aluminum tooling on top held the c-frame shaft straight up and down and had some guides on the bottom outside of the spar flanges to keep it positioned over the rivet. Strike the rivet with the hammer 3-6 times and slide to the next rivet, repeat. I used some wood as spacers under the length of the spar to keep it level at the correct height to accomodate the steel block with the cupped rivet set.
I can't take credit for the tooling, I borrowed it from another builder who I've since lost contact with.

Mark
 
The pros and the cons...

Well...as I can see it, hammering seems to be a satisfying & unexpensive method...I am still a little bit impressed to drive those rivets...and still willing to invest for the right squeezer...as a military pilot very used to stressing my birds !:eek:

I will make my decision......thanks a lot for your replies !
 
Those big rivets....

A BFH is Ok if that's all you have......Here is another approach.....hydraulics. Homemade c-frame and a single acting (spring return) cylinder ......Once you have it built makes life very easy....and quiet too !! just another idea.
ps: the dial indicator was use to get the same size shop heads.....Pump it up till you get .035 spread in the yoke and they are done.


 
When you use a rivet gun to do the spar rivets, set it up in the C Frame and put the rivet gun on the tool set. You can get perfect results like this and don't need to try to use a bucking bar. (My C frame came with two sets, one tapered for the rivet gun abd one with a blunt end for the hammer method.)
I have done two sets of spars using the C frame, one with a 2lb hammer and one with a 4X rivet gun. They both came out great, although I must admit it was a little easier with the rivet gun.
If you have a C frame, I don't know why you would ever want to use a bucking bar for this application.
 
Big rivets..no biggie!

While seemingly intimidating to the novice, 3/16 AD rivets are relatively soft.Believe me, there are some really big rivets (1/4,5/16,3/8)out there! I have spent a career in heavy jet structural maintenance, which does give me a slight edge, however, If you can find a 4-5x gun and use a heavy (5-6lb.) bucking bar,they will be a snap.I shot all my RV-4 spar rivets in a couple hours..by myself. The trick is learning to start shooting SLOWLY, and increase the trigger pressure over a few seconds...this way you have control and dont jump off the rivet head. Good luck!
 
Big squeezer

When I did my RV-6 in the late 80's I used a squeezer I borrowed from Van's. IT was awesome. I would beg borrow or steal a nice squeezer. Other methods works but the squeezer is just so perfect. It gives nice results with I think less chance of mess up. Like Mel said Van used to lend one out, but I have some doubts if they still do, but does not hurt to call.

George
 
3/16

yes they do loan you one for i think 20$ and you can keep it for time you will need that info ihave from vans 1 month ago
 
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