Blind Rivet Question

[RVG8tor]

When we set normal rivets we have tolerances for shop heads. How do you evaluate a blind rivet to determine it is set properly? I only ask because when I was setting the AD-41 ASP rivets on my rudder leading edge some stems broke with the first full instead of the second pull. I am using a HF pneumatic rivet puller, when I practiced with it, it would take two acutations to set the rivet, one pulls the rivet tight but does not break the stem the second actuation would finish the set. This is basically now it worked with the hand puller. On the ones that broke the stem on the first pull the rivets seem to be set, the heads seem tight to the surface and the bulbed ends do not seem abnormal. Is this OK or should I drill these out and try to reset them. BTW these are the rudder leading edge rivets. Thanks in advance, I tried a search for the answer but did not come up with anything on point.

Cheers

[jferraro17]

Originally Posted by RVG8tor

When we set normal rivets we have tolerances for shop heads. How do you evaluate a blind rivet to determine it is set properly?
Cheers

"Blind" faith?


Joe

[DGlaeser]

Blind rivets have a fairly large grip length range, compared to solid rivets, so the number of strokes on the puller varies with the thickness of material being fastened. Just make sure the thickness is within the grip range for the rivet being used and everything should be OK.

[tagold]

As long as the grip length is long enough and not too long a blind rivet will be set properly when the stem breaks. If the stem pulls out and doesn't break, then I would redo it. If the left over piece of stem falls out of the inserted end of the rivet, use a longer rivet.

On another note, I'm really surprise the HF puller is requiring two strokes. On my Sonex, I can't remember any of the rivets doing this and they are stainless steel. The aluminum ones that Van's uses should pull really easily. Maybe try a higher pressure on the puller. It should have plenty of stroke.

[borislav]

Originally Posted by RVG8tor

I only ask because when I was setting the AD-41 ASP rivets on my rudder leading edge some stems broke with the first full instead of the second pull.

This basically means that the two layers of the rudder skin were not completely flush against each other, so the rivets set with a shorter stroke of the puller. They may look flush outside, but because of the curved bends may not be flush on the inside - you can tell by looking into the hole before you put the rivet in.

Since the leading edge is not structural, I wouldn't worry about it, especially if it looks OK.

[Captain Sacto]

Poster Boris writes... Since the leading edge is not structural...

And as I'm nearing the rudder leading edge construction, I'm wondering if the leading edge might actually have some structural importance.

It seems to me, as a non-engineer, that the leading edge might provide some key torsional stiffness for the rudder spar. In fact, I'm thinking of putting a small blob of tank sealant between the pulled rivets, just to add a bit of torsional strength to the rudder spar.

(I could be way off base, but it won't hurt anything.)

[Norman CYYJ]

If Van's wanted the leading edge of the rudder reinforced he would have had it called out in the drawings. This is an area that you don't want to add any extra weight.