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dspender

Well Known Member
Patron
Sometimes when I am riveting the rib flange to the spar, the flange starts out flush to the spar but by the time I have set the rivet the appropriate amount, the flange tip has lifted up a bit from the spar. Why? Is some of the rivet expansion separating the flange from the spar? Is this just the flange bending under the force of the compression? Do these need to be removed?
 
I have had this happen on occasion, but in most every case it was just the edge of the flange separating, ie at the location of the rivet the surfaces are still tight. I try to follow the rule of putting the factory head on the thinner surface, which may help as well.

It also seems to help to me to have the air pressure set properly so that I am not hitting rivets either too hard or for too long. Not saying that is your problem, just that I noticed this happening more on my left wing before I got my pressure settings perfected, and has not happened at all as I built my right wing.

I believe that in most cases, if the surfaces are flush at the rivet location, the damage risked by rivet removal would be worse than leaving the joint as-is with a properly set rivet. Especially because these joints are usually tough to access with a drill. I'm sure there are other equally or more valid opinions...
 
If you can put the factory head over the thinner piece that usually helps. Some have put O rings, or short pieces of vinyl tubing, on the bucking bar or squeezer (shop head side) to help push the pieces together.
 
Wasn't sure what 'factory head on the thinner surface' meant. But I figured that out. Placing the factory head on the flange and the shop head on the spar. My difficulty with this is getting the rivet gun close enough to the rib to keep the head perpendicular to the flange and rivet. I have an offset rivet head, but it rotates as I an driving the rivet and doesn't stay fixed in place. As it rotates my rivet gun gets even closer to the rib. So you don't think rivet material is separating the flange from the spar and if it is not to be concerned?
 
Dennis,
So long as the rivet is not setting between the spar and flange, you are ok and there is not much you can do about it, short of putting factory head on thinner, which is not always possible. The flange lifting up a bit around the edges is no problem. Regarding offsets... Use the shortest one possible and, if you can find a helper to buck, use two hands, one on the set itself. Finally, you can often push the rib away while riveting if its not fixed at both ends. SnapSocs from Avery really help keep the set on the head, and also help when the set is not perfectly perpendicular. Highly recommend them! Hope this helps.
 
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I use medical tape with a bunch of wraps around the offset rivet set and the gun to keep it from rotating. Works very well. Masking tape over the rivet head helps keep the set in place.
 
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