[sglynn]

I've read, and heard it said that rivets can go either way. But look at this photo. I put the Universal Head on the bulkhead web side and when I bucked them the rib flange curled up slightly in some spots. I think it curled up because I had no pressure on the rib flange like I would if I had bucked from the rib flange side.

So, maybe if you are riveting a flange the Universal head should go on the flange side.

Is this gap condition ok to fly?

 

[Greg Arehart]

Steve,

I think that rivets can be driven from either side and should have the same holding power. In some cases, there may be clearance issues that require installation in one direction, but I don't think for strength it matters. The one you show was probably not bucked quite right. I would drill this one out and rerivet it to tighten it up. Such a gap will not allow the rivet to be full strength.

My 2 cents.

greg

 

[ignacio]

i agree they can be driven either way but i have had better results with universal head on the thinner materiel, helps with the upwards bending while driving.

 

[RV7Factory]

In this particular case I would have shot them the other way so that you are pushing the flange or the rib towards the web of the spar center section, rather than away from it.

In general I agree that its best to have the manufactured head on the thinner material. There have been times when I have done it the other way and regreted it.

 

[noelf]

I have my own theory for the cause of honeymoon rivets...

...If you are over-aggressive in deburring the rivet holes, you end up with a sharp knife edge around the rivet hole and not the "squared-off" shoulder that is desired. When the two sheets of aluminum are brought together, these knife edge holes are allowing a small gap to exist between the aluminum sheets at the rivet hole location.

When the rivet is driven, the knife edge gap allows the rivet to start expanding between the sheets and this is what causes the "swelling between the sheets".

 

[mototopo]

Following the suggestion on this forum and experiencing by myself I found that putting the manufactured head on the thinner materiale helps to mantain a tight fit between the pieces you are riveting. By the way, there are some circumstances in which, for various reasons, this can't be accomplished. So, when I have to put the shop head on the thinner material, I use a rubber grommet between the bucking bar and the material to push it against the other piece to be riveted. It works with pneumatic squeezer too.