Flush Rivet Question

[PlaneDan]

I made a rather complete post on this subject on Saturday or Sunday and it never showed up, so I will make this brief. I used my DIENQ as suggested by Tony on a sheet of .025 6061 T6 that I purchased for the purpose of doing this test. I drilled thru two strips of the material, 23 holes, with #40. I then used the "swizzle" deburring tool to deburr all holes because I don't have a #40 burraway. I then dimpled all the holes in each sheet,

DIENQtest_02.jpg

clecoed every other hole with #40 and updrilled to #30 with a drill bit.

DIENQtest_04.jpg

I thought that I would then have to deburr again, but it was not needed. I then installed the -42 rivets with zero proud stems. I do not think the -42 look as good as the -43, but since they are what is called for in the plans, I will use them unless I run into proud stems in real life. I am including a couple of pics and hope this post makes it.

[BobJacoby]

Thanks Mike,

Really appreciate you sharing your test results and insights. Also, good description of how and why to set the air pressure on the pneumatic rivet puller (i.e. you want to pull the stem slowly so it properly sets the rivet before breaking the stem).

I just ordered a slew of low-profile, dome-head, stainless-body, stainless-shank rivets to test:

http://www.rivetsonline.com/stainless-s ... -head.html

haven't made any decisions yet, but I'll post my impressions / test results in a few weeks.

Bob Jacoby
Panther SN: 0018
Jacksonville, FL

[Greg Pixley]

Mike, thanks for the info. I've had no issues (proud stems) with the BSC-43s so far and will continue to use them. To answer Dan's question regarding stainless, I won't use them without testing first. I've used them before on my Thatcher and have a bunch left.

[MikeS.]

I spent a lot of time making rivet samples, using every rivet combination that seemed feasible, both protruding and flush. The BSC-43 was the superior flush rivet in my testing. I also modified the pilot of my dimple die by reducing the diameter down to .116”.

I found Stainless Steel tubing that has a 1/8” OD and a .115” ID. Cut a piece of this tubing to fit inside the female portion of the modified die to keep the pilot in proper alignment. Drill or file out the ID of the SS tube so the pilot doesn’t hang up. McMaster-Carr Part # 6100K472.

Drill the skins with a #40 drill, then a #32 drill, deburr the hole, and dimple with the modified dimple die. With this setup the hole diameter after dimpling should be around .128”.

A new 3/32” cleco will fit in a #32 hole without any issue. Just don’t try to use an old cleco or you could pay the price with a deformed perimeter around the hole.

I would suggest that every builder make their own rivet samples and select the rivet combination that produces the best results for their effort. I was surprised at my repeated results, and based on this I’m sticking with the BSC-43 for flush applications.

You should be able to minimize proud rivet stems by setting the pneumatic rivet squeezer to the lowest pressure that will pull the mandrel very slowly. Suggest placing a regulator right at the inlet of your squeezer. Don’t let your squeezer jerk the mandrel out of the rivet. That does two negative things. It makes the rivet weaker (less compression of your pieces of aluminum) and it can cause a proud stem.

For the occasional proud rivet stem my suggestion is to push the stem into the body of the rivet; it does so with very little effort. Put a drop of medium CA glue into the hole and the stem should never rattle around for the life of your airframe. If you get a proud stem that want push into the hole then carefully grind or file it down flush.

As for protruding rivets I like the CCP-41 and the Cherry Max CR3212 series.

Your results may vary. Mike

Updated McMaster-Carr part number; 6100K472

[rlweseman]

The proper grip length for rib to skin is a 41 rivet. The 41 rivet we tested with blew out the back too often. The 43 was the next rivet up that was available when we built the prototype and testing produced a tight fit with little to no proud stems. I have just received a batch of 42 from another vendor and will be testing with these.


Rachel

[PlaneDan]

I am just curious, why do you think that stainless will be better?

[Greg Pixley]

Being an impatient person, I also tested them on some scrap, then used them on the rudder without issue. If I can't find some -42s that work just as well I will either continue to use the -43s or use stainless.

[PlaneDan]

I had either heard or read that -43 were used on the Prototype. Given that, are they acceptable for use on our Panthers? And, if not, why not?

I got some .025 6061 from AS for the explicit purpose of testing these rivets. They do not pull stems, even when using the Burraway, and I could not pull them apart even though I was pulling on both sides of the piece held with only one rivet. I am still waiting for my DIENQ dimple die, but if it does not get here before I start with the skins, I am strongly inclined to use the -43.

I tried to post pics that I took of the test, but the site lost my post when I tried to upload. The pic was probably too large. I will have them on my site soon, if anyone cares.

[rlweseman]

They should be BSC-42. Sounds like you got the wrong rivets. We used 43 on the prototype, as 42 was not readily available.


Rachel

[Greg Pixley]

I just started the tail kit and noticed that it came with BSC-43 rivets for the skin? Grip length says I should be using a -41 rivet but it appears nobody sells these? I've built a plane before using -42 stainless to skin the plane (according to plans) and some of the rivets seem loose. Wanted to make sure I don't have the same issue with -43s. Any feedback?