rivet strength bidirectional?

[prkaye]

For round-head solid rivets, the plans do not typically indicate which side of the piece the shop-head goes on. I usually have just chosen the orientation that is most convenient for riveting/bucking.
I'm assuming that the strength will be the same either way...I can't see how it would be otherwise, but please correct me if I'm wrong.

 

[R.P.Ping]

Heavy side preferred

You are correct, but if you have a choice put the buck tail on the heavier of two sheets. Although I remember the instructions for the wings called out to put the rivet buck tails on the heaver skin but I did the opposite because it was easier to install them the other way. They came out just fine and I didn't have to drill any out in the process.

Do the best you can and don't be overly critical.

 

[bullojm1]

The recommended way to install the universal head rivets is such the shop head is on the thicker material. If it is done the other way, the thinner material tends to distort in my experience. That being said, when I looked at a set of QB wings where the main ribs and spar are riveted together, the shop head was on the rib flange. I try to set everything the recommended way when possible, but if it is going to be too much trouble to set, I always opt for the easy way - Less frustration/drillouts/cursing/slowdowns.

 

[dan]

If it is done the other way, the thinner material tends to distort...

Yep. And when we have a joint that is primarily in shear, if the material distorts (scallops?) then we're giving away strength. Some of the strength in a shear joint is provided by FRICTION. If we take away surface contact, we take away friction, and thus we take away strength.

Shop head on the thicker side when possible!

 

[nucleus]

Shop head?

Okay, I don't know this, which end is the shop head?

 

[bullojm1]

Okay, I don't know this, which end is the shop head?

The shop head is the one you make in the shop, of course -- i.e., the one that looks different after you set it. The other side of the rivet is called the manufactured head, which is either round or countersunk from the factory.

 

[az_gila]

The bucking bar end....

Okay, I don't know this, which end is the shop head?

The end that contacts the bucking bar in normal riveting....

gil in Tucson

 

[Jekyll]

It comes down to a decision hierarchy:

1. Must the rivet go in a specific direction due to the ability to drive it?
2. Will you ever need access to drill it out for future work? If so, the manufactured head goes on the side that provides drill access.
3. If 1 and 2 are non-factors, then the shop head goes on the thicker materiel.

When all else is equal, put the manufactured head (round head) on the visible side for exposed rivets. Manufactured heads look better than shop heads. An added bonus is that your shop heads won't be critiqued by every Tom, Dick and Harry, especially glass builders.

Jekyll

 

[alpinelakespilot2000]

Absolutely ditto on what Jekyll just said.

 

[alpinelakespilot2000]

Do the best you can and don't be overly critical.

Also, just to endorse Roger's point and add something, Phil, since today seems to be the day (that all of us have) where you are questioning your riveting quality...

Without endorsing mediocrity, keep in mind that of all the RV's that are out there, I don't think there is any documented case where a rivet failure caused a mishap. Whenever I go to airshows and look at all kinds of planes, RVs or otherwise, I'm often amazed at both some spectacular riveting and some really ****** riveting. Point is that they all fly pretty much just as well. (This is how I sleep at night anyway! )

 

[prkaye]

today seems to be the day (that all of us have) where you are questioning your riveting quality...

It's true, I do frequently have days when I wonder if I really trust my own craftmanship enough to be building something my life will depend on. I sometimes lay awake at night thinking about a bad rivet, or a question about torque, and think to myself "I must be mad for doing this...". I just hope when i start flying I can put all this out of my mind and enjoy flying it without a constant paranoia of it falling apart!

I don't think there is any documented case where a rivet failure caused a mishap

That's something I've often wondered about. We hear about the occassional accident/incident resulting from engine mishaps, poor pilot technique, weather, etc. But how often do we hear about structural failure of an RV resuling from normal use... i.e. not including situations where somebody exceeeds the rated loads by yanking on the stick. In other words, has an RV ever fallen apart because the builder was sloppy, be it with rivets, or torquing bolts, or... ?

 

[az_gila]

Smoking ones....

....
Whenever I go to airshows and look at all kinds of planes, RVs or otherwise, I'm often amazed at both some spectacular riveting and some really ****** riveting. Point is that they all fly pretty much just as well. (This is how I sleep at night anyway! )

Yes... but poor rivets (especially loose and not fully set ones) will lead to the "smoking rivet" effect after a period of flying.

Re-setting (or replacing) rivets on a nicely painted plane can be difficult and can spoil an expensive paint job....

Don't aim for too low a quality... or if you do, don't paint your RV....

gil in Tucson

 

[prkaye]

What's a smoking rivet?

 

[Brantel]

In other words, has an RV ever fallen apart because the builder was sloppy, be it with rivets, or torquing bolts, or... ?

Don't know but I was told of an RV that sat in the show section of Sun-N-Fun this year that was missing tons of rivets and the ones that were in there were horible not to mention the other comments about gaps, extra holes, cracks, poor deburing etc. Did not get the pleasure of seeing that plane but as such I guess these things are over engineered. Thats good for us that are not perfect so we can sleep at night.

 

[Brantel]

What's a smoking rivet?

A loose rivet that rotates and creates a slimey black smokey plume around it on the paint. Looks like an oil leak sometimes.

 

[prkaye]

that was missing tons of rivets

MISSING RIVETS?? Was that aircraft flying?? WOW... I can't even imagine how a person could climb into a homebuilt airplane with missing rivets! That certainly puts into perspective my worries about the occasional over-set or crooked rivet!

 

[Brantel]

MISSING RIVETS?? Was that aircraft flying?? WOW... I can't even imagine how a person could climb into a homebuilt airplane with missing rivets! That certainly puts my worries about the occasional over-set or crooked rivet!

Yep, holes that were dimpled, painted etc but no rivets! I heard this report from more than one person that saw this plane on different days.

 

[alpinelakespilot2000]

Yes... but poor rivets (especially loose and not fully set ones) will lead to the "smoking rivet" effect after a period of flying.

Re-setting (or replacing) rivets on a nicely painted plane can be difficult and can spoil an expensive paint job....

I agree. The potential of having smoking rivets after I've already painted seems to be more of the motivating factor for replacing rivets for me these days, especially because I plan to paint myself! I wonder how poorly a rivet has to be set to create the potential for smoking later??

 

[kentb]

It is a rivet that will soon develop lung cancer...

What's a smoking rivet?

It happens when any two pieces of metal can move against one another and results in a trail of metal particles "smoking" back from the point of contact. I found one on my wing the other day. I hope to be able to put a little more paint on it to seal it off.

Kent

 

[Jekyll]

Smoking rivet = working rivet = fretting rivet. Looks and feels like graphite streaking back from the rivet.

Got a local 6 with many missing rivets. It's reminds me of a whiffle ball. Many pulled rivets in lieu of driven. Pulled rivets on wing skins that didn't go through the ribs (skin is not attached in several places). Metal that was rough cut with snips then riveted down without ANY final fitting or edge treatment. Exterior painted with spray cans (unintended zebra stripe effect). No primer under the exterior paint.

Basically, a terrible thing to do with a perfectly good Van's kit. It looks like a 5th grade class project without any adult supervision.

He managed to get it certified and not only does it fly but, it doesn't seem to know how ugly it is.

I won't ride in it and I would likely run for cover if it flew overhead but...it's flying and mine is still in the garage.

If this guy's is holding up, I wouldn't worry much about an ocassional poor rivet.

Jekyll