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  #1  
Old 03-15-2019, 08:01 PM
MJarreau MJarreau is offline
 
Join Date: Apr 2007
Location: LA (Lower Alabama)
Posts: 221
Default Measuring Flush Rivet Heads

How do you measure the amount a rivet is proud of a surface?

Thanks,
Mike
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  #2  
Old 03-15-2019, 08:35 PM
rv7charlie rv7charlie is offline
 
Join Date: May 2006
Location: Pocahontas MS
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Are you talking about the shop head? The factory head should be perfectly flush.
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  #3  
Old 03-15-2019, 08:36 PM
David Paule David Paule is offline
 
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Location: Boulder, CO
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I use a dial or digital caliper. They have the capability of measuring the depth of a hole or step, so I place the end of the body on the head of the rivet, and the stem on the skin. It's important to hold the caliper perpendicular to the skin.

And it's worth making several measurements and averaging them, at least for me, because the likelihood of getting two or more the same seems to be small.

Dave
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  #4  
Old 03-15-2019, 09:46 PM
rv7charlie rv7charlie is offline
 
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Location: Pocahontas MS
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Best to not overthink it. Try to find the milspec on shop heads; you'll find that quite a bit of variation is tolerable. If you use the length called out in the plans, and make sure the 'stack' is tight, then bucking 'til the shop head is just past the minimum diameter spec will be all you need for a good rivet.
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  #5  
Old 03-16-2019, 11:33 AM
MJarreau MJarreau is offline
 
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Location: LA (Lower Alabama)
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Default Flush Manufactured Heads

Charlie and David,

I meant the height of the manufactured head vs the surface into which the rivet is installed. We have installed only a handful and are not pleased with the result.

Charlie, thanks for pointing out the mil spec, we learned how to use that some time ago and use a micrometer, and now the guages purchased with our kits, and understand the use of those.

We will try David's idea. We also thought about purchasing a feeler guage at a auto parts place and simply trying to feel the difference.

Thanks!
Mike
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  #6  
Old 03-16-2019, 11:41 AM
Marc Bourget Marc Bourget is offline
 
Join Date: Apr 2009
Location: Stockton, California
Posts: 197
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If you are speaking of standard AD rivets, I would look first to your dimpling technique.

When I first started, wary of the "softness" of the Alu, I was always under forming the dimple. You have to "coin it" in the vernacular.

Play with some scrap and increase the force applied to your dimpling set up.

Stop short of marring the surface of the sheet around the die.

If this doesn't work for you I'd check your dimple dies.

FWIW
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  #7  
Old 03-16-2019, 10:16 PM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
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Quote:
Originally Posted by Marc Bourget View Post
If you are speaking of standard AD rivets, I would look first to your dimpling technique.

When I first started, wary of the "softness" of the Alu, I was always under forming the dimple. You have to "coin it" in the vernacular.

Play with some scrap and increase the force applied to your dimpling set up.

Stop short of marring the surface of the sheet around the die.

If this doesn't work for you I'd check your dimple dies.

FWIW
Iím not sure how to interpret ď stop short of marring the surface around the dimple dieĒ but if when dimpling, the skin surface isnít getting lightly scuffed under the entire area of the dimple die face, the dimple is not being fully formed and it will have a noticeable effect on how the manufactured head lays in the dimple.
The reality is, it is very hard to over dimple, but under doing it is very common.
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  #8  
Old Yesterday, 07:18 AM
birddog486 birddog486 is offline
 
Join Date: Mar 2016
Location: WI
Posts: 63
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If your shooting the rivets with a gun and bucking bar, sometimes the rivet will set proud if the bucking bar is being push to hard against the rivet. It only takes a light touch with the bar unless your shooting a thick and rigid stack up.
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  #9  
Old Yesterday, 08:02 AM
rv7charlie rv7charlie is offline
 
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So, if we're talking about the factory head, then what Marc & Scott said. Birddog is right about bar pressure, but underdimpling will give a bad result *every time*. Here's a useful video from Cleveland tool showing what underdimpling looks like:
https://www.youtube.com/watch?v=Qo9QCMaNSoA

On a flat surface line of rivets, you should be able to stand a straight edge (ruler from a combination square, etc) on the line of driven rivets, and barely see any light while shining a flashlight from the other side.

Like Scott said, it's almost impossible to *over* dimple.
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  #10  
Old Yesterday, 08:09 AM
TShort TShort is offline
 
Join Date: Jan 2005
Location: Indianapolis, IN (KUMP)
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I found that when dimpling with the C-frame I got better results if I hit twice. First hit would set the dimple, then the second (harder) hit would ensure that it was properly formed.

As others stated, it is really easy to under-dimple.

Using the DRDT-2, I found I had to really have it adjusted so the dies were fully engaged even without sheet metal in there - this allowed me to get enough pressure for a good dimple.
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