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Missed dimples

B

Barneybc12d

Well Known Member
I failed to dimple these 7 holes in the .025" skin for 1/8" flush rivets. Is using the pull die mandrel with pop riveting tool the only option? Will a bucked female die and the male die in the rivet gun do the job without damaging the sheet?


1124myr.jpg
 
I'd probably use the pull rivet mandrel.

If you are careful you can get good results with them.

-Dan
 
I have bucked a female die and used a rivet gun with the male die, HOWEVER, it is very easy to mess up the AL sheet with that technique. If you choose to do so then practice with scrap material A LOT. Otherwise, the pull rivet technique will be adequate and much safer. Just my 2 cents.
 
I made , but I think you can buy a metal punch /holder for the dies. A friend holds the female die inside while you strike the male die holder with a hammer. Keep things square to the skin and make sure the dies do not slide on the skin.
 
I have successfully done this with the rivet gun as well. They key to doing it -- that I have found -- is to turn the pressure down with a regulator and use very short bursts.
 
Ken Martin said:
I have successfully done this with the rivet gun as well. They key to doing it -- that I have found -- is to turn the pressure down with a regulator and use very short bursts.
Click to expand...

I have used the rivet gun/dimple die combo on missed dimples. I never had a problem or gave it much thought. I guess ignorance is bliss in my case.
 
I've built a few airplanes. I've used the pop rivet dimpling tool exclusively. Never had an "extra" hole. Never had a problem.
 
It's been a while since I've done this, but it's never been difficult to find the nails. Just take your dies with you and find a finish nail that fits.

When you are dimpling, start with the air pressure very low and increase slightly until you achieve a good dimple. I can usually do an entire wing skin with about 3 nails.
 
Pop Rivet Mandrels

I threw away the nails from the getgo - not enough pulling force (IMO) before the head popped off. So I have used exclusively the steel mandrels out of pop rivets that best fit the holes in the dies & skin. These mandrels are designed with a "frangible" stem - it breaks at an engineered axial load, and is (within manufacturing limits) repeatable. The breaking load is much higher than any nail I could ever find (maybe some hardened ring shank nails would work - just never tried them), and there was always a ready supply as close as my rivet assortment. On -4 holes I opened up the holes in the dies to accept a larger mandrel in order to get more "pulling power" - in some instances you don't need to break the stem to get an acceptable result, and you can keep using the stem/die combination over and over again until fatigue takes over and it finally breaks.

I "harvest" a selection of mandrels ahead of time and keep them with the die sets for ready access when needed.

YMMV - but I'll bet that if you have "gone over to the dark side" and used these mandrels for this purpose, you won't go back to nails anytime soon!

HFS
 
**Edited for clarification***

I have used both pop rivet dimpler and used the rivet gun/bucking bar with squeezer sets.
I preferred the shape of the dimple made by the gun/sets over the shape by the particular set of pop rivet dies I had. (maybe they were not the quality that Mel used) They did not make sharp dimples and the heads frequently stood a bit proud.

Turn the pressure way down on the gun and take it easy to prevent putting a "smile" in the sheet.
 
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rzbill said:
I used both pop rivet dimpler and used the gun.
I preferred the shape of the dimple made by the gun over the shape by the particular set of pop rivet dies I had. (maybe they were not the quality that Mel used) They did not make sharp dimples and the heads frequently stood a bit proud.

Turn the pressure way down on the gun and take it easy to prevent putting a "smile" in the sheet.
Click to expand...

Bill,

That is a great idea, don't know why i never thought of that!

-Dan
 
I missed those same holes.

What I did is:

I have a very heavy bucking bar (steel) that is about
10" long. (You could use any big piece of steel).
I drilled a hole for the female dimple die in the end.
The I pulled the shaft out of my c-frame dimpler
and put the male dimple die in it.

I held the solid bar inside the plane while my wife lined
up the part outside, and I pushed up against the
skin while she whacked the c-frame shaft with the
hammer.

That way they came out just like any other c-frame
dimpled hole.

I do have pop-rivet dimple die tools. I am not sure if mine is
a 3/32" or 1/8" though, and although I've used it before
and made good dimples, I wanted these holes to be
dimpled as well as possible since they would be very
visible and they hold the seat belt bracket.

I think the pop rivet tool will work fine too, and you can
always start with that and change your mind if you wish.

Tim
 
A Rev. 1 version of Section 10 was published to the Van's web site on 10/17/14.
A revision that addressed this issue was part of that update.
All builders that have e-mail info registered with Van's should have gotten an e-mail notification about the update.

The Section 10 update can be accessed HERE

A list of all updates issued for the RV-14 can be Accessed HERE
 
I want to start building an airplane again JUST so i can use old mandrels in a pull rivet.

This is one of those tips that's so obvious, I never thought of it.

Great suggestion.
 
LettersFromFlyoverCountry said:
I want to start building an airplane again JUST so i can use old mandrels in a pull rivet.

This is one of those tips that's so obvious, I never thought of it.

Great suggestion.
Click to expand...

Bob, you can't use old mandrels. You have to remove them from uninstalled rivets so that they still have the nub on the end.
 
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good rivet gun

I have used both the pull dimples and a rivet gun. The pulled dimples seem to be a little shallow with my set.

If you use the rivet gun, the technique already described with a female die attached to a large bucking bar or steel tool works best for me. It is very important to have a rivet gun with a true teasing trigger on it. I have an old Chicago Pneumatic gun that does this.

By turning the air pressure down carefully you can get the gun to deliver just one soft "pop". That usually does it. An experienced IA at a repair station showed me how to do it.

It also works for stubborn rivets that should fit but which won't go all the way in and now won't come out. A little tap does it.

Get the best rivet gun you can afford.
Dave A.
 
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I'd recommend the pulled dies as well.
I've done a few using the rivet gun and the dimple dies and found you can turn the pressure WAY down and after only a few taps with my 3X gun it turned out well, but try the pulled method first.
 
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