extruder in reverse. Instead of a flat surface like you have under the
1410's head the cone of the dimple helps slowly work the c/s rivets head off
or reshaping it. Then when the load comes off the rivet's loose and things
start to move around. I've found them definitely not an item you want in any
tension application..
----- Original Message -----
From: "Ken" <klehman@albedo.net>
To: <rebel-builders@dcsol.com>
Sent: Thursday, December 13, 2007 2:20 PM
Subject: [rebel-builders] 4412 vs 4410 rivet shoot out
Hi Wayne
The BEST "data" is always experience! Numbers seldom lie but our
assumptions and interpretations are often wrong.
So I just tested some series rivet joints with both kinds of rivets.
With 16 or 20 thou strips of 6061-T6 aluminum stretched in tension
(rivets theoretically in shear), the countersunk 4412 failed before the
4410 showed any distress every time. Actually the rivet did not fail. No
heads popped off. But in every case the aluminum sheet gradually pulled
away from the flush rivet head and the flush rivet head pulled through
the sheet leaving a large hole. Very little deformation of the sheet on
the shop head (backside of the rivet). It was as if the act of
dimpling started the process and applying force just made the dimple
deeper and twisted the rivet until the rivet head tore through the
sheet. These were avex rivets purchased directly from Avdel Textron. I
can easily imagine this process popping the heads off but it didn't in
this particular scenario.
My sample size is anecdotally small and I don't know how much force I
was applying with the hydraulic press. But I'm convinced that the 4410's
do make a stronger joint regardless of the rivet strength. All the
deformation around the 4412 was absorbing energy rather than failing
suddenly but it seems to be a lot easier to tear a rivet through a
dimpled hole than to shear it. If the head popped off it would be even
easier. I bow to Wayne that dimpled 4412's make weaker joints than
4410's but I don't know how significant it is in practice.. What do you
think Wayne? I assume you figure you've seen situations where there
would have been no likely damage with 4410's or you figure the damage
was worse because of 4412's. I can't imagine the heads popping off with
no other damage but there are different manufacturers and different
batches of rivets...
OK now we're having fun. Using a stronger structural Q rivet likely
won't provide a benefit in this tear through scenario but what about
upgrading to a 5/32" avex flush rivet? I used a 1/8" dimpling tool but
the rivet still pulled pretty much flush. Well it is indeed stronger
than the 4410 and showed no distress prior to the 4410 failing. In this
case the 4410 started to enlarge the hole in the sheet and then failed
suddenly with the head popping off and shooting across the room.
Ken
(still learning but having fun)
Wayne G. O'Shea wrote:
Sorry Ken... I don't care what the "data" is... I'm speaking from how many
heads I've seen come off of the 4412's vs 1410's..used in the exact same
locations.
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