Flush Avex

[Capt T]

I am sure this subject has been addressed but, I am new.
I am asking if any builders here chose to use Avex flush rivets in place of round head rivets on their Sonex.

Aside from the work involved to achieve a flush riveted skin, are there any big negatives that presented themselves?

I have heard the "Why would you want to do that?" question many times. I simply want a smooth finish and I am not the least little bit worried about the work involved; only any problems others may have encountered.

Kit supposed to ship this week!

Appreciate it.
Capt T

[Bryan Cotton]

I know Rick (racaldwell) flush riveted his Xenos. The main downside i would see is that I had a percentage of mandrels pop off proud of the surface and that required extra work. So extra work is the main reason not to do it, but of course that's a good reason to buy a Cessna rather than build. Go for it!

Edit: I have minimal flush rivets. Leading edges and other places that required them.

[Area 51%]

The easiest/fastest way to experience the joys of dealing with proud rivet mandrels (flush or otherwise) is to make sure the holes are too large.
Someone out there makes a dimple die with a 3/32 pilot. After dimpling is the time to bring the rivet hole up to size with a reamer. Do keep in mind the pulled rivets require a 1/8in hole and NOT a #30. .

[Bryan Cotton]

Do keep in mind the pulled rivets require a 1/8in hole and NOT a #30.

Whoops - did not know that. Where is it written?

[Area 51%]

Whoops - did not know that. Where is it written?

After suffering through a few proud mandrels, I bothered to measure the OD of the pulled rivets V.S. the AD rivets which do require a #30 to get through a hole without a persuader.
There's about a .002" difference in diameter in the rivets along with an extra .002 increase in diameter of the hole with the #30.
.004" makes for a sloppy fit.

Making things up as I go along here @Area 51% .

[WesRagle]

I had the "proud mandrel" problem on my first Sonex build. On the Onex I got one of these and was happy with the results.

https://cleavelandtool.com/products/dimple-die-set-for-1_8-avdel-n-or-q-40-pilot

Seems they are out of stock at the moment.

Wes

[DCASonex]

Depending on your dimpling die, your initial drilled hole size will be larger after the aluminum is stretched by the die. The die I got from Sonex back in the dark ages (14+ years ago) had a much steeper angle than the 120 degree rivet head required and grossly over stretched the holes.. It was an easy job to make a new die set on a lathe, a standard 118 degree drill bit seemed to make a perfect seat leaving only the male half of the die to actually be machined, and that is pretty simple.

David A.

[builderflyer]

I am sure this subject has been addressed but, I am new.
I am asking if any builders here chose to use Avex flush rivets in place of round head rivets on their Sonex.

Aside from the work involved to achieve a flush riveted skin, are there any big negatives that presented themselves?
Capt T

To the best of my knowledge, Avex aluminum rivets have never been approved for building a Sonex product. For those who do not wish to use protruding head rivets, others have used the stainless steel flush rivets as sold by Sonex to create a smooth surface more easily polished. Wish I had done this but it wasn't an option at the time.

Art,,,,,,,,,,,,,Sonex taildragger #95,,,,,,,,,,,,,,,Jabiru 3300 #261

[Bryan Cotton]

To the best of my knowledge, Avex aluminum rivets have never been approved for building a Sonex product. For those who do not wish to use protruding head rivets, others have used the stainless steel flush rivets as sold by Sonex to create a smooth surface more easily polished. Wish I had done this but it wasn't an option at the time.

Art,,,,,,,,,,,,,Sonex taildragger #95,,,,,,,,,,,,,,,Jabiru 3300 #261

Aren't the stainless flush rivets from Sonex also avex? Or a reasonable facsimile? I do have some aluminum avex which I use for non-structural stuff.

[karmarepair]

To the best of my knowledge, Avex aluminum rivets have never been approved for building a Sonex product. <snip>
Art,,,,,,,,,,,,,Sonex taildragger #95,,,,,,,,,,,,,,,Jabiru 3300 #261

Aren't the stainless flush rivets from Sonex also avex?

They are NOT. I don't know where they source them, but they are the same EXPANDING mandrel style as the original United Shoe Machinery patent. For DIMPLED holes in THIN aluminum, it's SUPER easy to pull the mandrel through before the head is fully formed. That's why if you're using them in this manner, drill #40, dimple, THEN ream to the tightest hole that will accept a rivet.

AVEX rivets have a different Mode Of Action. The mandrel COMPRESSES the hollow stem until it buckles to form the head. They are MUCH less susceptible to pull through in dimpled holes.

I suspect Stainless Steel Avex are a Thing, but I've never seen them in retail quantities.