Started Riveting the Nutplates for Securing the LE Removeable Section to the Subskin

I started out by free-handing the attach rivets for the first couple of edge nutplates on the subskin with the pneumatic squeezer, but even though I was able to set these OK, I did not like the risk and the inability to hold that beast of a heavy squeezer with only one hand while holding the subskin in the other. So before I set any more rivets, I had to rig up another custom method of clamping the subskin to allow the proper support and positioning of the part for riveting the nutplates on. Here is the initial setup using my padded 4x4 wood blocks (3 of them) and the bar clamps similar to what I have done before:

I had to reposition and reclamp the part for each new rivet, sliding the subskin as close as I could get it to the clamped blocks without causing interference between the squeezer and the clamps. I also added a second clamp on the other side to tighten up the structure. This allowed me to use both hands on the squeezer to set the rivets.

I used my 3 inch yoke which had enough clearance from the edge of the subskin to set all of the edge rivets on both sides. The 4 remaining nutplates on the rear edge of the top and bottom of the subskin will have to be bucked - oh boy - there is something I have not done in a while. 

Also shown in the above pic are the flat rivet sets that I used. The thing I hate about nut plates is that the rivets that attach them are on either side of the center shaft for the screw. This does not leave very much room for positioning the rivet sets so as to be centered over the rivet shaft without being too far over to one side to ram into the screw thread shaft, thus destroying the nutplate. ON the other side of the nut plate exists the possibility that you could slide too far away from center, causing an incorrectly set shop head on the rivet. IN order to avoid hitting the screw shaft, I needed to use a 3/8 inch wide flat set (on the top of the yoke in the above pic), and the 1/2 inch wide flat set on the bottom which goes over the manufactured head of the rivet. This means that the squeezer must be positioned as centered as possible to avoid either condition described above.  And may I say that it is a royal pain in the ass having to use a flat set that is that small to do all the mashing of the shop head. 

Lets just say that so far I have had to drill out about 4 rivets because of this, and I may have to replace one nutplate after damaging the edge of it when the squeezer slipped while squeezing, to the point that I am not happy with it. The other thing that sucks about this session is that I cannot position the squeezer very easily in such a way that I am able to pull against the manufactured head with the top of the yoke, so that the ram that moves from the bottom does not displace the part or cause the squeezer to slip out of position as it travels upward. Instead I have to keep the extremely large squeezer body on the outside of the part, which forces me to do the opposite by placing the moving ram on the manufactured head of the rivet instead of the shop head. The result so far is 4 badly set rivets that needed to be drilled out and replaced. 

The good news is that I was able to set almost all of the edge nutplate rivets on both sides of the subskin using the pneumatic squeezer. And the rivet heads seem to be pretty flush on the subskin surface where the removeable section will be sitting on top of them, so I was happy about that as well. Here is the result of one side of the edge nut plates installed:

I should also mention that I used my rivet gage to determine the size of the rivet that I needed - the winner was AN426AD3-4 rivets, These set very nicely in the dimpled nutplate flanges and left more than enough of a correctly sized shop head. 

You can tell that I have riveted anything in a while, because I also forgot one other cardinal rule that I had established long ago when using the pneumatic squeezer to set the rivets. The instructions for this tool say to set it to 90 psi, but  found that this tool has just too much force at that setting, and this can cause the tool to shift out of position or ram with such force that it almost damages the part. So I found long ago that setting the air pressure to 75 psi works a lot better. It does not activate as violently as it does at 90 psi, and it still maintains enough force at that settings to more than adequately set AN426 rivets.  Here is a shot of the air pressure setting for posterity later on.

Another shot of all the clamps in position

And finally a shot of a successfully set nut plate using this setup. I made it all the way to the last rivet on the last edge nutplate and managed to screw that up because I got too fatigued and wanted to finish it. So I drilled that one out and will reassess that one tomorrow. Then I will need to come up with yet another custom clamping setup so that I can buck the remaining rivets on the remaining nutplates  When that is done, the subskin goes back into the LE skin for the final time, where all those millions of dimples will also be riveted together into a solid LE with all the custom work completed.