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Measuring Flush Rivet Heads

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
 
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.
 
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
 
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
 
Marc Bourget said:
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
Click to expand...

I?m not sure how to interpret ? stop short of marring the surface around the dimple die? but if when dimpling, the skin surface isn?t 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.
 
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.
 
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.
 
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.
 
I'm gonna take a stab at this, because I had similar concerns when I first started on the tail of my RV-8.

I tried riveting the skin on my horizontal stab and wasn't happy at all with the way the flush skin rivets sat. None of them were perfectly flush.

I found out that I was under dimpling. I read something that referred to the dimple dies as "spring-back" dimple dies. This got me to thinking about bottoming out the die set in the squeezer and then giving that extra little push. And, sure enough, there was a bit of spring back when you let off. It leaves a perfectly symmetrical little halo on the dimpled skin, around the rivet hole when done properly. Its especially noticeable when using the DRDT-2 that is bolted down to a sturdy surface.

Try this and see if it doesn't cure your problem.
 
TShort said:
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.
[snip]
Click to expand...

I use a fat (~3" dia) heavy rubber mallet with the C-frame. 2nd hit is like driving a 20P framing nail; quite hard. And the C-frame needs to be on a surface with zero flex; either a concrete floor, or on a sturdy bench directly over a leg that's sitting on a rigid floor surface.

Charlie
 
Thanks to All

We were able to use the suggestion by David quite successfully. I really appreciate all of your suggestions!

Best,
Mike
 
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