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wing ribs to main spar riveting

Raybilt

Member
Hey guys,
I finally got back on my -7 build and it has been going fairly well. That was, until I began riveting the wing ribs to the main spar. I ended up with approx 20 rivets that should be replaced. I used a 10 degree offset rivet set on my 3x gun with the little red plastic cover installed. I work alone, which is probably part of the problem. I completed one wing and am about to start on the other. Any suggestions?
 
I tried various bent & offset sets with lousy results, & finally settled on the longest straight set I could find, with 'hockey tape' over the tip. If the flanges are clamped well with clecos, the main ribs can be flexed to the side slightly, allowing an almost perpendicular shot at the head.

I'd send pics of all the bad ones to Van's, & ask their advice on replacement. Often, what looks really horrible to us is still a serviceable rivet, and often, drilling one out can result in a weaker joint than just leaving it alone. While you're asking, ask about pulled rivets in those locations. IIRC, at some point they've said pulled rivets are a viable option on the main ribs.
 
I used a Cleaveland double offset two handed to keep it from turning, and brought my wife in to buck (first time). Came out great less one rivet that I drilled and reset.

The nose ribs are going to be tough, already got a note back from Vans to use pull rivets there, but the challenge is holes are right up against the main ribs, going to be tight even with the little wedge trick-
 
Here's the deal. You need some additional gear that will use time and time again, so it will be by no means a one off purchase just for this task. Once you've got this gear, those rivets will be easier than shooting rats in a barrel.

1. Tungsten bucking bar. There are numerous posts on the forum discussing this and the one that gets called out time and time again is the one to get (the 1lb thin rectangular bar with one end slightly canted). The 1lb bar still seems to work fine on the 1/8" rivets, as tungsten seems to punch well above its weight category. Don't ask me why, but there's some type of magic going on there.
2. 12" straight rivet set. This will allow you to bend the rib slightly out of the way and shoot almost straight onto the rivet. Be sure to put some duct tape on your gun in places where it may rub on a rib so that it doesn't mark your primer/alclad. These longer rivet sets can be a little hard to find, but you can try Cleaveland Tool or Brown Tool. You will need plenty of pressure/flow to run these longer sets due to their mass, so try them first off the aircraft, and don't forget to turn your gun down afterwards or you will mash the next rivet you shoot if you go back to using the regular rivet set.
3. Snap Socks. These plastic caps fit over the head of the rivet set and stop it marking things so badly if you don't shoot square. I never shoot a AN470 without them. You will just need the orange 1/8" size available from Aircraft Spruce. They are ridiculously expensive little bits of plastic, but worth every cent. Value pricing I think is the official term. I prefer to call it daylight robbery. One bag should do you for the build.
4. Place some duct tape around the rivet you are shooting incase things don't go to plan. Two layers if you are really nervous. Saves damaging your expensive spar or web.
Good luck.
Tom.
 
Thanks Charlie. What is "hockey tape"? I will send pics to Van's. Thanks again.

Basically, cloth reinforced bandage tape.
https://en.wikipedia.org/wiki/Hockey_tape

The stuff I used was non-elastic (probably 'stick tape' in the link above). Just google 'hockey tape' & you'll see hundreds of places to buy it. It adds just a bit of friction between the set & rivet head, so the set is less likely to move sideways if you let it 'float' while driving the rivet.

Note that I learned this from others; I'm from the South, too. My only prior knowledge of hockey was via the nickname Don Rickles gave me.
 
Tip

There's an easier way. Take a look at my blog.
Support the spar with wood blocks over a couple EAA work tables end to end and high enough for the back rivet bucking bar. Adjust height with some foam. Ribs will be up. Rivet one rib at a time so they are not flopping around on clekos. I used my back rivet plate with the back rivet bar on top then a tungsten bar on top of that. Adjust height with foam so the rivet doesn't touch the bar. When you drive the rivet, flex the rib over enough to drive the rivets. The foam allows the assembly to flex down so the rivet shank hits the bar and you get perfect shop heads. No need for offset or extra long rivet sets and no messed up shop heads.
I used LP4-3 and LP4-4 on the leading edge ribs.
 
Thanks to all of you for your input. Quite frankly, I was getting a bit discouraged and your input has been a great pic-me-up.
 
I actually just did this about two or three weeks ago. I had garbage results with any kind of offset rivet set. I went to a straight rivet set with the spring removed and taped all of the rivets, they instantly started turning out perfect. I also had to tape the sides of ribs where the gun would touch it to avoid scratching the primer.
 
Take a look at my blog. I used wirejocks method for back riveting some of the ribs but found it a bit tricky when you get to the thick parts of the spar. So I switched to using a 2X4 clamped to the table as a bucking bar rest. Then I used a long straight rivet set cause I hate using the double offset set. You just have to move the rib over a tiny bit to clear the gun but it works sooo good. Just have a buddy hold the bucking bar on the rest and shoot the rivet. Move the bucking bar rest to the next rivet. The rest works perfect for someone inexperienced with holding a bucking bar!
 
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