Rough day working with pulled rivets

This weekend I installed the flap gap fairings on my QB wings. After contacting the mothership for advice on a substitute for the inboard rivets, I started installing the MSP-42 cherry rivets suggested. During the pull on 2 of the rivets, the stem broke low enough that I can't get a grip to finish it out.



Afterwards, I thought I'd move to another job - correcting a goof on the battery box install in the tail cone. This is the intersection of F1029 and the F1007 frame. The suggestion from Vans in this case was a BSPQ-5-4. During the install the stem broke as well, but worse than that the bulb on the backside doesn't look even close to well formed.





Reason for my post is twofold:

First - I did enough of the blind fasteners on the horizontal to remember to keep the stem perpendicular to the piece. Is there anything else that could be causing the stems to break (tooling is my first thought)?

Second - Obviously these need to be replaced, but some technique suggestion would be appreciated. I had to drill out 1 previous blind with the stem still present and it turned into a disaster because the drill wandered and enlarged the hole. I don't want that in my spar. Any suggestions on an easy way to pop out the stem?

Sometimes even the easiest jobs are enough to drive you mad!

We remove the occasional pop rivet working on our "Brand S" project, and have found that the easiest way to remove the stem is an automatic center punch with a small-diameter tip (grind one down if you have to - they are cheap at Home Depot). Just pop away until the stem exits the other side for parts unknown....

It happens

like Paul said, you might have to grind down the broken stem, a dremel works great for this then using an automatic center punch drive it out backwards. You can then drill out the head. Just make sure you only go deep enough to break off the head. Don't try to go all the way through.

Jason

TFeeney said:

Is there anything else that could be causing the stems to break (tooling is my first thought)?

Click to expand...

I'm curious what kind of rivet gun you're using? We're using the el-cheapo pneumatic riveter from Harbor Freight, and after doing the blind rivets on our fuel tank zees, some Proseal got in there and interfered with the tool grabbing on to the rivet stems properly. Had to really go in there and clean it all out. Sounds like you have QB wings (lucky!) so maybe not Proseal from the tanks, but is it possible something else might have gotten into your riveting tool and skewed the way it clamps on to the stems?

Just a thought...

Thanks for the suggestions.

My rivet puller is from Cleaveland Tool - very minor use, but not with proseal. I'll check tonight for contaminants though - maybe a chip of aluminum or something.

Check for proper tip size. You want the hole to just pass over the stem. I has a problem with Cherry Max doing just like yours. Took a smaller dia. hole tip from another gun and problem solved.

Ron B. said:

Check for proper tip size. You want the hole to just pass over the stem. I has a problem with Cherry Max doing just like yours. Took a smaller dia. hole tip from another gun and problem solved.

Click to expand...

I just took a small piece of .032 and drilled a small hole in it and slipped over the rivet shank before pulling. I have a Marson rivet puller, it worked pretty well.

Google "cherrymax rivet removal video"- there is an EAA youtube vid on it. Always knock out the shank before drilling.

Thinking out loud - - The end of the rivet puller nose has a conical shape that spreads the jaws. When the jaws are pulled up(handles squeezed), they close and pull on the shank. Is it possible that the shank length available for engagement is too short for this tool? If so, could the tip be modified to allow more shank engagement? Like shortening in a lathe - maybe both ends?

Edit: Looking at the pic closer, it might be the larger hole in the puller is pinching the hole around the shank.

I had some do the same thing

I have several manual blind rivet pullers. One I particularly a like that I used on my RV-4 years ago. However I found when using it on my RV-7A project sometime the mandrel (stem) of the blind rivet would break off prior to the final pull. I finally retired the puller and used some of my other ones.

I think the cause of the problem I had was the "jaws" were very sharp and "bit" into the stem aggressively causing a "notch" in the mandrel causing it to break of prematurely. Also I believe the mandrels aren't as hard as the ones when building my RV-4.

Every time I use a manual rivet puller I always do a two pull sequence. I initially pull until the head expands. Then I reset the puller with the handles close together. This does two things. One it repositions the "jaws" that they "bite" into the mandrel at fresh location, second you can get more pull force when handles are closer together. Additionally with the handles closer together you avoid the chance of getting your other fingers smashed by the handles when the mandrel breaks off (been there done that )

Food for thought.