| Main Spar |
| November 12, 2007 |
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| Back Riveting.... Michael Style! |
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| Pretty simple stuff so far, all you need to begin is a rivet and a hole. Shown is a AN 470-5-6 solid rivet. The 470 just means it has a protruding head on it. The other types of rivets we use are the 426's, these will have a flush head. The - 5 means its is a 5/32" round rivet. The first (-) dash number indicates rivet diameter in increments of 1/32". So if it was a -3, it would be a 3/32" rivet. The next (-) dash number indicates the rivet length. This number, oddly enough, goes up in increments of 1/16". So this rivet is 6/16" or 3/8" in length. |
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| Place rivet in the appropriate sized hole. This hole is a #21 and is used for the 5/32" rivet. |
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| Rivet tape. The green part is sticky, while the clear part is not. So when you upset the rivet (otherwise know as pounding the crap out of it), it will not stick to the rivet head, leaving you or your loved one the joy of peeling off tiny pieces of tape from the rivet head. I normally drive about 4-5 rivets at a time, this pic is for illustration purpose only. |
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| I flipped the spar over. We will pound on that little protruding head... also know as the "shop head." You can remember this term because it is the part you will form (or smash the crap out of) in YOUR SHOP! |
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| OK... here we go. The rivet gun with the Back-Riveting Set on, it is positioned over the shop head. The Bucking Bar...just a big hunk of metal (bought from Sonex) is under the Manufactured Head of the rivet. |
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| Make sure the white cup is down flat and the rivet gun is straight. Hold onto the white cup while riveting, or it will vibrate and move all over the place. On these bigger rivets I have the air pressure all the way up to 90psi on my el'cheapo HF air compressor. Make sure everything is solid and squeeze the trigger. Just need to practice to see how long to squeeze the trigger. I did the squeeze-check, squeeze-check method... looking at, and measuring, the rivet for the correct upset each time until I got it right. |
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| First I would measure the diameter of the shop head. The shop head should BARELY NOT fit in the hole on the rivet gauge. * This is according to the instructions provided with the gauge. I know everyone has their own ideas and opinons about this* |
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| The key is to smash the rivet where the diameter is correct while not smashing it too much. The "too much" is determined by the height of the shop head. Here we are testing the "too much" part. If I put the gauge on my shop head (like above) and you can see light between the two, the rivet is overdriven. Any more driven, and my rivet would fall into the "too short" category and I would need to drill it out and start over. |
| Sonex suggest that you can use a bolt and small sledge hammer to set the rivets. You can, and it works wonderful! Just be sure you are on a SOLID surface..like the garage floor. (Otherwise your workload will increaese. It took about 6 heavy blows to set the rivets on my table. On the floor I would guess it would take less than half that many times.) I chose the rivet gun because I did not want to be on my hands and knees trying to work. And my father has a hard time getting up and down all the time. |
| Blue line shows the rivets I have in at this point in time. My work is from the middle-out. |