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Double flush Rivets

Driving '67

Well Known Member
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Just working on the flap brackets and the plans call for double flush riveting. This is a new process for me. Any suggestions/pictures on how to get a clean shop head on the back side.

Thanks
 
pound it down until it fills the countersink then remove any rivet that is above flush.
A rivet shaver is nice, but you can use a scotchbrite disc on a high speed grinder.
 
When double flush riveting is called for in RV construction manuals, it is not calling for a rivet shop head to entirely filling the countersink. This is particularly important on control surface riveted trailing edges where the shop head is being form into a dimple on relatively thin material. If you try and use a rivet that will fill the dimple, it will distort and pucker the skin in the area of each dimple.
A shop head that reaches a normal 1.5 D diameter and is somewhat flush with the material surface is what is expected.
More info can be found in Chapter 5.8 of Construction Manual Section 5 located HERE
 
It's the flap brackets he is talking about not the rudder trail edge.
 
So for the countersink on the shop side, should the "depth" be slightly more shallow? Is the intent just fill the hole at 1.5X diameter and remove any rivet material above the surrounding surface? Is it acceptable to have a "slight" countersink hole visible after the rivet is set?

I'm still practicing on scrap pieces but trying to determine what a high standard job looks like.

Thanks Jim
 
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Flush would be ideal. Better high then remove excess than below countersink. Thing is to fill countersink fully. Don't worry about 1.5 diameter in this case. Like 2002 said this is not for thin parts that must be dimpled. He was speaking of items such as the rudder trailing edge which is another process.
 
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I was talking about all double flush rivets on RV's.
There is not an expectation for a fully filled countersink.
If the recommended length rivets are used on the RV-14 (or the RV-10) flap hinge brackets, they are not long enough to fully fill the countersink.
Even as thick as the material is on the hinge brackets, it is possible to cause distortion in the material by trying to fully fill the countersink.
Hinge bracket trailing edges that are straight are much more important than having the shop head countersink fully filled with the rivet.
If you countersink to a depth on both sides that would result in a flush fitting manufactured head, and then install the specified rivet with a flush rivet set on both sides using a squeezer and squeeze the shop head flush to the surface, you have met the structural expectation for this part.
If this technique is used you will still be able to see some of the countersink around the perimeter of the shop head.
 
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Gentlemen,

Thanks for the replies, I have a much clearer understanding of what is req'd.

Cheers Jim
 
This thread is timely as I am just working on the RV14 flaps. I have chosen to alternate the rivets and this shows both the manufactured and shop head. As Scott described you can see some of the countersink visible around the shop head and in this case the shop head is very close to flush with the surrounding part.
To completely fill this countersink would require quite a bit of pressure, using a longer rivet, and even though the metal is thick it could distort the metal and also put excessive pressure on the "hole" itself.
As a side note; there are some minor, visible, machining marks on the flange from the bending process and I will buff those out before calling this part complete.
1r4yfk.jpg
 
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Excellent. Thank you a brazilian for the picture. I am headed to prime the rudder and vertical stab this weekend and will get some .016 tomorrow from ACS for practicing with on my little scrap of rudder trailing edge wedge. Hope to work on that trailing edge one night next week. So this photo is well timed and will serve as a great reference.

I am interested in the alternating rivets and will be interested to read feedback from the group and rvb002.
 
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