Riveting HS rear and front spars

With the primed parts fully cured, I could begin the final assembly of the horizontal stabilizer.

Riveting the rear spar was my first time extensively using the squeezer during the build. The trial and error of setting the appropriate gap between the sets wasn't a difficult process, but I ended up drilling out the first rivet. I had squeezed it probably 10 times to get the proper setting and the shop head was looking pretty deformed. I replaced the bad rivet and continued riveting the spar doublers and hinge brackets to the rear spar pieces.

As stated in the plans, hand-squeezing AN4 rivets takes a bit of grunt. I had to clamp the spar to the worktable and weigh it down on either end to keep it from moving while I exerted pressure with the squeezer. The Cleaveland main squeeze is nice to have here since it claims to require less force than competing squeezers. Considering the amount of effort I still had to use, I'd hate to imagine having to use another squeezer here. The longer rivets (the -7s that go through the spar doublers, spar, and hinge brackets) were a bit of a challenge by themselves since they are liable to fold over if the squeezer isn't held perfectly square.

With all of the rivets set on the rear spar (aside from the holes left empty to later attach the front spar assembly) I bolted the center hinge bracket bearing onto the spar. These bolts will need to be torqued and sealed, but I'll only hand tighten them for now and take care of torquing during final assembly.

The front spar was next. Once again I had to re-countersink the holes in the HS-710 and HS-714 angles since the primer had increased the thickness of the holes. I did my best to squeeze as many rivets as I could, but the 3 inch yoke on my squeezer wasn't quite long enough to fit around the wider HS-714 angle and reach the holes on the HS-710. Out came the rivet gun, which easily took care of those.

The HS-00005/6 ribs were a pain to rivet. The plans suggest "gently flexing" the ribs out of the way to reach these rivets. I was again forced to use the offset rivet gun attachment, of which I'm now very wary. Flexing the ribs out of the way while also holding the gun and bucking bar perfectly square proved once again to be a challenge, and my first attempt at using the offset attachment left me with a nice row of smileys on the flange after it bounced itself off the factory head. After a few minutes of fuming and cursing I went back to it and managed to carefully muscle my way through the rest of these rivets on either side. Hopefully I won't have to use the offset attachment much later on in the build...

My efforts yielded a interesting wall piece.