Brief Description: Remove solid rivets from spar 2/2
Continued because of Kitlog Pro's *^&#@<&! 2048 character limit!!
3. After some experimentation, I concluded that the best procedure was pretty much as recommended in the Zenair Photoguide:
- Hit the rivet with a 3/16" hand punch and a hammer until the rivet material was knocked just below the surface of the base metal. Note that this did not mean that the rivet shank was actually moved. Usually it just meant that the slightly drilled metal at the mfg head end of the rivet shank was compressed a bit into the hole. Pushing the end of the shank below the base metal surface provided a guide to keep the rivet gun punch on the rivet and to avoid damage to the spar from the rivet gun punch.
- Then I used the rivet gun with the 3/16" punch to knock it out the rest of the way. It took ~3 very short bursts at max air pressure (70-75 psi) to drive out a 3/16" rivet.
- As suggested by many builders, it was very important to securely clamp the spar cap structure so that the spar cap, doubler, web, and angle could not separate when driving out the rivet. I concluded that the best procedure was to clamp the spar very tightly to the jigs with C-clamps. The jigs were set on the table ~5 rivet pitches apart. Then use a 3rd C-clamp to clamp the cap as closely to the rivet being driven as possible. That usually meant setting the 3rd C-clamp for each rivet. this required that I move the 3rd C-clamp for each rivet, but the result was that none of the rivets got hung up in a separating assembly. A typical set up is shown in Fig. 2.
4. The rivets were ejected rather violently from the spar caps. Fig. 3 shows a rivet shank stuck into the wooden backstop I put behind the spar to prevent the extracted shanks from hitting anyone.
5. Removing the 5/32" rivets took much less force. I dinged the spar cap angle a couple of time when I held the trigger for too long. With hind sight, I probably should have dropped the compressor pressure down, perhaps to 45 or 55 psi.
