Canopy Rivets - Breaking Mandrels

I'm ready to rivet my canopy to the frame. I decided to pull a few test rivets (AACQ-44's) in some scrap material to see how they fit in the countersink. All 5 I pulled resulted in breaking the mandrel about 1/4 inch above the rivet head! I've seen mandrels break before, but not 5 in a row. (I tried 2 different pullers).

Anyone else experience this problem and what was the solution? I really don't want to have to grind off a hundred mandrels. Thanks.

Larry

My canopy (tipup) is glued with Sikaflex; I only used rivets along the curve at the baggage compartment. I also had a few pull through (about 5 out of the approximately 40) and I simply pulled them the rest of the way with vice-grips. Since I glued that area as will (thin layer of Sika), I am not really worried about the strength of the rivet and I will simply fill the hole. YMMV.

Thanks for the reply. But in the words of Gilda Raddner, " Never Mind!"

When I did the test, I used a piece of AL and a piece of canopy scrap, and broke all the mandrels. I thought about it and decided to put a piece of AL on the back of the sandwich to simulate the canopy tube then try it.... yup, you gussed it, no more problem. I guess the plexi was giving or something.

So much for my testing skills.

Larry

I'm glad you got it sorted out.

In the Airstream restoration world we use Olympic blind rivets and their mandrels are designed to break about 1/4" from the head. We cut the stem off with side cutting diagonal pliers or end nippers and shave the 'nub' with a rivet shaver.