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roll bar question: Rivets

Stockmanreef

Well Known Member
1. Should you counter sink the CS4-4 rivet a bit deeper than flush so that the back window does not touch the CS4-4 rivets after they are pulled.

2. How do you know if the cherry rivets that connect the roll bar to the roll bar brace are set correctly? I know that when I pulled some of the cherry rivets for other parts of the plane, I had to drill out because they were not pulled correctly. Since you can't see the inside of the roll bar, then how do you know if they are set correctly?

thanks
ken
 
@stockmanreef What's your indicator that your other rivets aren't pulled correctly?

Are you talking about the Cherry Max Rivets? They are different than the regular pop rivets, but ultimately work just the same.

At any rate, I just pulled mine normally and everything came out perfect.
 
I noticed that the set side (the inside part) were not all uniform in their set depth. I then looked up the cherrymaj spec sheet:

http://www.cherryaerospace.com/docs/catalogs/CA-1011.pdf

I may have also found something else. But on page 18 is shows what they should look like. A lot of mine 25 % were not set completely so that the safety lock was engaged. I drill out and they were super simple to get out. I assume that if they had been set correctly, then the removal process would have been more difficult. I could be wrong.

I might have taken pics. If so I will post later.

I used a pneumatic puller to set. But not one made specifically for cherrymax.
 
I'm using a hand puller, no experience with pneumatic, I wonder if they pull differently. Typically with the hand puller it takes two pulls, one to "set" the rivet and pull the surfaces tight, then another to fully engage the head of the pin into the shaft and snap it off.

Just a curiosity, I know it doesn't help you :p
 
the thread below talks about issues with pulling cherrymax rivets. Again my concern is not with longerons because I can see if they are set correctly. It is the ones that you can't see the inside so you will never know. At this point I will just by the special puller to be safe. What's another $100 at this point in the build?

http://www.vansairforce.com/community/showthread.php?t=155613&highlight=cherrymax+rivet+puller


Puller from Aircraft Spruce:

https://www.aircraftspruce.com/catalog/topages/cherryg27.php
 
It is the ones that you can't see the inside so you will never know.

The document you previously linked too, and Section 5 in the construction manual have details that explain that a properly set Cherry rivet will have the broken stem flush, or very nearly so, to the top of the manufactured head of the rivet.
 
roll bar brace clearance

p 38-03, top right corner, shows the washers inserted between the roll bar brace and the window; so there should be at least the washer thickness clearance between the brace and the plexi. Non-flush rivet heads, unless extreme, shouldn't be a problem.
 
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