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rivet hardening

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aerobubba(at)earthlink.ne
Guest

Posted: Sat Jan 19, 2008 4:46 am Post subject: rivet hardening

HI guys and gals-



This is not absolutely purely RV related, so purists please delete now!



I was talking to a friend a while back about riveting.  He is building one

of Monett's products, which is built almost exclusively with pulled rivets.

The only solid rivets are the big ones in the spar center section.  What my

friend learned at a Monett factory seminar is to put the factory head in a

rivet set on an anvil and smack the shop end with a hammer.  I believe they

were to use some sort of a striking bar or block to transfer the blow, but

I don't recall that detail perfectly at this point.  Anyway, what my friend

was told at this seminar is that one of the various reasons for doing this

is that this technique will properly set the rivet in fewer blows than

using a rivet gun, and that this in turn would lessen the work hardening of

the rivet.



This is not an intuitive conclusion for me, and I was wondering what the

metallurgists / professional metal workers / other smart folks out there

think?  



As a morsel for those purists who haven't already deleted, if this is a

valid point, perhaps we could make ever so slightly tougher structures by

using higher gun pressures while riveting.  



Thoughts?



BTW, I ZnCrO3 most things, glued my canopy, have a constant speed, IFR

panel, and the little wheel is in the back...   



glen matejcek

aerobubba(at)earthlink.net

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rgf(at)dcn.davis.ca.us
Guest

Posted: Sat Jan 19, 2008 7:52 am Post subject: rivet hardening

I'm not a metallurgist.  But as an engineer I'm guessing that the technique

described will increase a rivet's strength by just a very few percent.  It

strikes me as something that a perfectionist would want, but an engineer

would disdain as not being worth the trouble, given the highly redundant

strength of our multiple rivets already.  Obviously lots of planes have and

are flown built with rivet guns so I'm sticking with that.  And I would not

start experimenting with different rivet gun pressures and so forth!  Do

your experiments on something harmless unless you have formal education and

plenty of experience in the area.



--

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d-burton(at)comcast.net
Guest

Posted: Sat Jan 19, 2008 8:00 am Post subject: rivet hardening

Hi Glen,



This is a real issue.  We don't see it much with 99% of our little rivets

but driving the big ones in the spars is where we would.  I drove my spar

rivets with a small sledge hammer using my C-frame.  It worked great but I

had to really smack the rivet hard to have the least number of hits.  They

definitely got harder to drive each time you hit them.  I don't think that

it's a strength issue with work hardening but cracking and failure to flow

to fill the hole and form a good shop head.  



DavdB



--

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khorton01(at)rogers.com
Guest

Posted: Sat Jan 19, 2008 2:47 pm Post subject: rivet hardening

On 19-Jan-08, at 10:54 , David Burton wrote:



 	  Quote: 	
		   



 I drove my spar

 rivets with a small sledge hammer using my C-frame.  It worked great  

 but I

 had to really smack the rivet hard to have the least number of  

 hits.  They

 definitely got harder to drive each time you hit them.


	


The "getting harder to drive each time you hit them" isn't only due to  

work hardening.  The diameter of the shop head increases as you drive  

the rivet, so it takes a harder and harder force to cause the metal to  

move as you progress.



Given that there are over 5000 RVs flying that were built with the  

traditional rivet gun method, and they aren't falling out of the sky,  

I wouldn't worry about this, unless you are driving the big rivets on  

a main wing spar.  Those rivets either need a big rivet run, or a  

hammer.  The 3X or 2X gun used on the rest of the project won't cut  

it, and most folks aren't prepared to purchase another rivet gun for  

just that task.  So out comes the hammer.



--

Kevin Horton         RV-8 (final assemby)

Ottawa, Canada

http://www.kilohotel.com/rv8

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aerobubba(at)earthlink.ne
Guest

Posted: Sun Jan 20, 2008 6:49 am Post subject: rivet hardening

HI Ralph-



Re:  But as an engineer I'm guessing that the technique

 	  Quote: 	
		   described will increase a rivet's strength by just a very few percent.  It

 strikes me as something that a perfectionist would want, but an engineer

 would disdain as not being worth the trouble, given the highly redundant

 strength of our multiple rivets already.  Obviously lots of planes have

and
	


 	  Quote: 	
		   are flown built with rivet guns so I'm sticking with that.  And I would

not
	


 	  Quote: 	
		   start experimenting with different rivet gun pressures and so forth!  Do

 your experiments on something harmless unless you have formal education

and
	


 	  Quote: 	
		   plenty of experience in the area.


	


I think perhaps you might have misunderstood my comments and question.  I

wouldn't suggest folks start building RV's with hammers, and I have no

concerns about the strength of the 5K+ RV's out there.  It's an issue of

gaining / verifying a bit of knowledge and exploring it's application. 

Upping the gun air pressure somewhat isn't all that big a deal.  Forgetting

you have full line pressure on tap after a drilling operation and then

trying to shoot a rivet can have less than pleasing results, er, or so I've

been told  



Personally, I've come to prefer using higher pressures than Van's

recommends.  As far as the part about formal education and experience

goes...  well... if there were a riveting contest held between an average

A&P and an average homebuilder, I know where I'd put my money!



 	  Quote: 	
		  

 Hi Glen,


	


Hi Dave!



 	  Quote: 	
		   This is a real issue.  We don't see it much with 99% of our little rivets

 but driving the big ones in the spars is where we would.  I drove my spar

 rivets with a small sledge hammer using my C-frame.  It worked great but I

 had to really smack the rivet hard to have the least number of hits.  They

 definitely got harder to drive each time you hit them.  I don't think that

 it's a strength issue with work hardening but cracking and failure to flow

 to fill the hole and form a good shop head.  




	


Interesting.  In the conversation I had on the topic, it was presented as

relevant to all rivets.  Perhaps the intent was that it was preferable to

use a hammer on rivets that would be a challenge for the average

homebuilder's rivet gun.  Thanks for the clarification.



HI Kevin-



 	  Quote: 	
		   Given that there are over 5000 RVs flying that were built with the  

 traditional rivet gun method, and they aren't falling out of the sky,  

 I wouldn't worry about this, unless you are driving the big rivets on  

 a main wing spar.  Those rivets either need a big rivet run, or a  

 hammer.  The 3X or 2X gun used on the rest of the project won't cut  

 it, and most folks aren't prepared to purchase another rivet gun for  

 just that task.  So out comes the hammer.



Makes sense!
	




Thanks to all-



glen matejcek

aerobubba(at)earthlink.net

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