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1. 12:25 AM - Re: rivet sets (Terry Phillips)
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Many, many thanks to all who responded. I think I'm seeing light at the end
of the tunnel.
Post Mortem: I believe that I had a combination of factors fouling up my
riveting.
* As Jeff says, it is vital that the piece be securely fixed. I thought
I had done this with the jig, as shown in the photo 409. But I think that I
was wrong. I now believe that the structure probably rocked backward with
every blow from rivet gun, but the dynamics were such that the next rivet
gun blow struck before the rivet rocked back under the set. The reult was a
smashing of the bottom of the mfg'd rivet head.
* In trying to keep control of the rivet gun with one hand while I held
the bucking bar with the other, I found that by reducing the air pressure
to ~50 psi, I had better luck keeping the gun on the rivet.
* But, at this low pressure, my "well used" 3X gun probably required at
least 5 seconds (and way too many impacts) to form the shop head. After 5
seconds of pounding, the mfg's head softened from compressive heating, and
deformed easily (I produced some really awful mfg'd heads)!. It was
probably impossible to drive the 3/16 rivets reliably with this low
pressure because it just took too long.
* And, it required more skill that I have to hold the rivet gun steady
in one hand and the bucking bar in the other while driving the rivet, so
the rivet set moved around and obliterated the mfg'd head.
Pretty grim. So, I have made a much simpler jig to hole the practice bar,
just 2-2x4's with a slot on the edge to clear the rivets, bolted to the
edge of my table. With this design, there is negligible lever arm to flex
and bend under the rivet gun impact, see photo 415. My helper was not
available today, so, for practice, I screwed a piece of 1/8" x 1" steel
scrap to the back edge of the 2x4 with a 3/16" hole for a rivet, also shown
in photo 415. Then I could put a rivet through the hole and practice
riveting with full compressor pressure.
It was fairly easy to hold the rivet gun in place with both hands and avoid
mangling the mfg'd head. If I kept pounding long enough, the head would
soften and deform. The force of the rivet gun was easily enough to drive
the steel into the 2x4, resulting in a significant bend in the metal after
a while.
When my helper returns tomorrow, I'll try the new practice setup on the
practice bar.
One question--my heaviest bucking bar weighs 3 lb, 12 oz, probably heavy
enough. But, who sells 5 lb bucking bars?
Thanks again to all you who answered.
Terry
At 05:34 AM 2/9/2010 -0500, you wrote:
>Terri
>
>Something tells me the small piece you are practicing with is to hard to
>hold while riveting. I would suggest clamping the piece in a vise then
>hold pressure at all times on the head of the rivet use your body weight
>if you have to. hold the bucking bar against the rivet but let it bounce
>slightly as you squeeze the trigger. You get smiley faces because the
>rivet gun bounced on the rivet head from either removing the bucking bar
>before you stopped the gun or you didn't hold pressure on the head. Just
>like flying when you get it you will know it.
>
>BTW if you are using a 3 x gun it will just take longer to set the rivets
>but it can be done. A 4 x makes a world of difference.
>
>
>Jeff
Terry Phillips ZBAGer
ttp44~at~rkymtn.net
Corvallis MT
ZU-601XL/Jab 3300 s .. l .. o .. o .. w build kit - Tail & flaps are done;
Balancing the ailerons and working on the wings
http://www.mykitlog.com/N47TP/
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