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broken pop rivet mandrel

A

alpinelakespilot2000

Well Known Member
While attaching the z-brackets to my tank with the closed-end pop rivets, I ran into a problem I've never had before. My rivet puller pulled one of the pop rivets but chopped the mandrel off about 0.5" above the head rather than flush with the head. I'm not sure if it was because it was a crummy/cheap puller or whether I did something wrong, or because perhaps the mandrel hadn't been scored where it is supposed to break. Now there is not enough mandrel for the rivet puller to grap onto to cut it where it should be cut.

Anybody know why this happens? What do I do with it now? Just cut off the remaining mandrel with some wire cutters?

Steve
 
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Steve, This is nor unusual. Sometimes the rivet puller scores the mandrel and causes it to break off. Sometimes it's just the rivet. If the rivet is pulled sufficiently (it almost always is under these circumstances) just cut off the mandrel with side cutters or I usually cut it off with a cutoff wheel. Problem with the side cutter technique is that it leaves a portion which will cut your hand many times later.
Mel...DAR
 
Thanks Mel. That provides some peace of mind knowing it's relatively common. I'm pretty sure it pulled sufficiently before it broke, so I'll just use a cut-off wheel.

Steve
 
Steve,

This happened on at least five per tank on my z-brackets....couldn't figure it out, but they seemed secure, so I just cut them off like you were thinking of doing. Glad to hear that it is happening to others to.
 
Wills_9A said:
Steve,

This happened on at least five per tank on my z-brackets....couldn't figure it out, but they seemed secure, so I just cut them off like you were thinking of doing. Glad to hear that it is happening to others to.
Click to expand...

The more I think about it, I have an idea. I have not broken any up to this point anywhere. That said, the tank z-brackets are the first place where (even with most of the nose of the puller ground off) there is still a slight amount of angle while pulling. Maybe it is this slight angle that causes the mandrel to break in the wrong place. And yes, I'm glad it is happening to you too. (I wouldn't want all the misfortune for myself)! :)

Back to figuring out what size of Cherry Max to use on my LE rib-spar joint above the aileron bellcrank....
 
"Problem with the side cutter technique is that it leaves a portion which will cut your hand many times later.
Mel...DAR"

I had about 5 of these, also. Not a problem cutting them with dykes, as you will undoubtably be covering these with proseal, anyway. They do take quite a bit of force to cut, though.

Tracy.
 
After you cut off the mandrel, use a Dremel with a roung grinder and carefully grind off the remaining piece of mandrel still sticking up.
This worked well for me but be careful no to damage the surrounding skin. You can surround the area with electrical tape to reduce the likelihood of a slip marring the adjacent skin.
 
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