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11-16-2013, 05:16 PM
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Join Date: Jul 2013
Location: KAVL
Posts: 317
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Rivet quality issue
Hi all,
Before we start riveting the VS and rudder we started some test riveting on our C-frame and hydro-pneumatic hand squeezer and issues quickly arose with the results. All the rivets squeezed seem to "push" or lay over to one side. We cannot get a rivet to squeeze perfectly for anything. We've tried adjusting the air pressure, travel length of the squeezer, different dimple dies, and using different backing plates. Nothing will produce an acceptable result. Take a look at these pictures and help me figure out what's going on. All the rivets are 426 3-3. After match drilling using a #40 bit the hole was .101-.103 but after dimpling the holes opened up to .106-.110! The pictures seem to indicate the dimple hole is too big.

This one was set in the C-frame by itself and squeezed.

Here's our C-Frame

Take a look at the two on the right. They're "pushed" over.

Another one "pushed over"

Last one
Are we being unreasonable or is there something wrong here?
Thanks all.
Last edited by Jasonm : 11-16-2013 at 05:53 PM.
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11-16-2013, 05:32 PM
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Join Date: Jan 2005
Location: 57AZ - NW Tucson area
Posts: 10,011
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__________________
Gil Alexander
EAA Technical Counselor, Airframe Mechanic
Half completed RV-10 QB purchased
RV-6A N61GX - finally flying
Grumman Tiger N12GA - flying
La Cholla Airpark (57AZ) Tucson AZ
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11-16-2013, 05:32 PM
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Join Date: Sep 2007
Location: Central IL
Posts: 5,516
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The real experts will weigh in here, but that stand alone rivet did not look straight. If I put one in my hand or pneumatic squeeze, they compress straight.
I would say something is wrong. Something is wobbling or deflecting or not square.
Oh - your pictures don't show. Check in preview before posting and you should be able to see them. Sorry, I don't know how to fix them either.
Good luck in your investigation.
__________________
Bill
RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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11-16-2013, 05:47 PM
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Join Date: Jul 2013
Location: KAVL
Posts: 317
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I updated the image host and they work now.
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11-16-2013, 05:58 PM
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Join Date: Feb 2010
Location: Gardnerville Nv.
Posts: 2,828
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That is one fancy C frame, I would check for any measurable deflection or any longitudinally movement while squeezing the rivet. And check for Parallel die surfaces while under load. I built my own frame and bought the head unit, but had to go back and reenforce my frame with more material to minimize load induce deflection.
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7A Slider, EFII Angle 360, CS, SJ.
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11-16-2013, 06:02 PM
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Join Date: Oct 2007
Location: Iowa City, IA
Posts: 45
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several reasons
Rivets will do that if:
1. pneumatic squeezer is not perfectly vertical to the rivet itself.
2. rivet is too long for the material
3. rivet will not form correctly by itself, needs material to form to
__________________
RV-7A Standard kit
Empenage - Finished
Wings - Finished
Fuselage - almost done
Panel and engine done.
On to fiberglass.
VAF Donation 2020
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11-16-2013, 06:03 PM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
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To my way of thinking, this is a dimpling tool, and not a riveting tool.
Where did you get the pneumatic setup??? I like it.
__________________
Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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11-16-2013, 06:04 PM
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Join Date: Jul 2013
Location: KAVL
Posts: 317
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Thanks Bret. Deflection on the frame is less than 1/16" under full load. We've checked to make sure the head is square and perpendicular to the bottom plate. What makes me think it's the hole diameter after dimpling is that if we hand squeeze a 426 the result is the same.
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11-16-2013, 06:06 PM
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Join Date: Jul 2013
Location: KAVL
Posts: 317
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Quote:
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Where did you get the pneumatic setup??? I like it.
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Thanks Mike. The head came from Numatx and my father built the rest.
It does make one heck of a dimplier though!
Last edited by Jasonm : 11-16-2013 at 06:09 PM.
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11-16-2013, 06:07 PM
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Join Date: Nov 2008
Location: Shreveport, LA
Posts: 1,002
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Quote:
Originally Posted by Mike S
To my way of thinking, this is a dimpling tool, and not a riveting tool.
Where did you get the pneumatic setup??? I like it.
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Yep, I have tried to use my DRDT a time or two for riveting and they turn out just like that. For a test, try a hand squeezer and see if they don't turn out as they should.
I never bothered to try and figure out the way to make my DRDT smash a good looking rivet.
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