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markscogg

Well Known Member
I just got a 9 year old tail kit. The preview plans show cracked rivet heads, and list "rivet too old" as one possible cause.

Should all the rivets be replaced?
Just solid rivets, or pop rivets as well?

Total cost of all rivets <$50

Thanks
Mark
Charlotte, NC
 
Try them...

Try them....

I've been using some 15+ year old ones, and they work OK.

Keep the length of the rivet "burb" reasonably short..... I think too many hits work hardens them, new or old.

gil in Tucson
 
Age shouldn't have a WHOLE lot to do with it. I don't think you'd run up against any problems.
 
I got some old rivets from Van's in my 6 mo old wing kit. The aileron push rods use AD4-12 rivets to attach the rod ends. When I tried to set the shop head on these, the shop head of the rivet would shear off at approximately a 45 degree angle. I tried setting the rivets with a squeezer and a rivet gun. I took the rivets I had left to an A&P that lives in the neighborhood and he put them in a coffee can and heated the rivets up through the coffee can with a torch. Basically, he annealed the rivets. They worked great after that.

I don't think rivets get hard very fast. It takes years. I suspect the ones I got had been sitting around somewhere for a very long time. If I were you, I would probably start using what you have. It's very obvious is the rivets have hardened. But then again, it's only $50...

It's only the solid rivets that harden. Blind rivets should be fine.

Wade
 
New kits, and probably yours, include a "trim bundle" to use as you see fit. Since practice riveting never hurts, why not set a few of each type of solid rivets with a gun and a few with a squeezer, and check 'em out? If a magnifying glass reveals any cracks in either head, either replace or try annealing.
I remember (sort of) hearing about putting rivets on a cookie sheet in the oven, but don't remember how hot or for how long. Any body reading ever try this?
 
Generally the only problems you will find are with the 3/16 rivets - they will split, or go into shear, if they are "old". They can be reclaimed by heat treating, but usually its not worth it. Pop rivets wil be fine. I'd try a few and see how they go, you should have no problems with the -4 & -3s.

Pete
 
Last night I was riveting the aft fuselage bottom skin with my wife--particularly those long fore-aft rows of rivets where the side skins meet the bottoms skins. All the rivets where the same size, using the same bucking bar, holding it in the same position, etc., but what I found is that about 1 of every 8-10 rivets refused to set as easily or quickly as all the others around it. In some cases, they almost refused to set. Instead taking a 2-3 second shot, they required multiple 2-3 second shots. What causes this variability? Is it that some of my rivets (pulled from the same bag) are older than others, or are some rivets just harder than others?

Anyone else noticed this tendency? Just curious.
 
found this from a google search, but it agrees with what I have been told by other builders. I know a couple of builders that did this and they said it makes a big difference. I'm not that picky, mine have worked fine so far, although I have occasionally had a difficult one.

"The process of heat treating (annealing) rivets is much the same as that for stock. Either an electric air furnace, a salt bath, or a hot oil bath is needed. The heat treating range, depending on the alloy, is 625? F to 950? F. For convenient handling, rivets are heated in a tray or a wire basket. They are quenched in cold water (70? F) immediately after heat treating. "
 
Rivet Info

Our rivets are the AD alloy which is 2117 T4 aluminum. The 2xxx series aluminum is alloyed with copper for its strength and that is obtained through a heat treating process, in this case labelled, 'T4'.
That means the alloy is solution annealed by heating to ~925degF until all the copper goes into solution and then it is quenched in room temperature water. The alloy is now about as soft as it will ever be until it is aged. The second part of the T4 heat treatment process involves this ageing. The alloy is naturally aged (time at room temperature), which causes strength and hardness to increase, until the strength stabilizes mostly and then it is used.
The strength increases because the copper atoms diffuse into locations in the aluminum crystal structure replacing an aluminum atom at that site and, due to their difference in size, they distort the crystal lattice and cause an increase in internal stress in the alloy that is manifested in higher strength and hardness. The bulk of the alloy's ultimate strength is achieved fairly quickly but it will continue to harden at a very slow rate over a much longer period. This "feature" causes the installed rivets to gradually increase in strength after we have finished building. This may also be the reason some very old rivets tend to be less malleable and fracture when bucked.
The older rivets can be softened again by heating to something less than the solution annealing temperature (~650F) and allowing them to slowly air cool, but the resulting rivet will no longer age harden and will never be as strong as the T4 heat treatment.
 
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