Solid Rivet shop head size criteria

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BBerson

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Hmm, I guess I have a few of those NAS Shear head rivets and didn't know what they were. I thought they were rejects with small heads. Anyway those small heads certainly don't need a full standard shop head. So one standard doesn't fit all.
I do have a couple explosive rivets also. Never tried one. I cut the end off of one and it does have powder inside. I would think the shop head after explosion is not that perfect, more like a pop rivet.

On heat treating rivets, I have done that quite a bit. But always have some concern with getting accurate temperature. Still experimenting, but I think heat treating is beyond home practice if other schemes can be found.
 

Pops

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Is that with a helper to buck? More tricky to hold the gun and bar both without messing up.

You are correct. Easy to mess up when doing it by yourself. That is why my daughter always helps me rivet. She runs the gun and I used the bar. We will get in a rhythm and work a long time and never say a word.
 

Angusnofangus

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[QUOTE="Mad MAC, post: 524909, member: 1369")

Or a little black box that runs the Heat Treat and chill of a modest number DD rivets at a time, softer driving, better fatigue, stronger joint (there could be quite a market for a little black box like that).
[/QUOTE]
At a place I used to work we had a small pottery kiln that was used in a travel kit for cooking DD rivets. I don't remember the temp you need exactly, but somewhere around 950F, so your kitchen oven won't work. And, yes, cooking DD's makes them very easy to drive.
 

BBerson

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Alcoa book lists 940F for 2117 alloy. Must be plus or minus 10° tolerance. That's the hard part.
I have a $10 yard sale antique dental heat treat oven that worked for a while. No easy way to calibrate it.
 

Mad MAC

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if you are heating rivets by small batches, an induction heater coil sized to heat a couple of rivets at a time might give the required control, it would at least be repeatable and quite likely automatable (power draw looks something like 2 kw so pretty manageable).

Edit 2000w looks like overkill.
 
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BBerson

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I can heat them easily with a propane torch. But no good way to get to the proper temperature. If done wrong might get intragranular corrosion. Doing some reading last night about annealing at 650°. Annealed 2117 rivets might be twice as strong as 1100 "A"" rivets. Aircraft Spruce has a full selection of soft "A" rivets and I don't know where anyone is using them widely?
 

BBerson

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Another comment from the Van's link:

"Tests have shown that very small rivet heads are sufficient to develop the strength of the rivet shank, even when the rivets are subject to a straight tensile pull....where a large head is not needed for appearance, smaller sizes of drive head should be used to decrease the required driving pressures."
 

Angusnofangus

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Another comment from the Van's link:

"Tests have shown that very small rivet heads are sufficient to develop the strength of the rivet shank, even when the rivets are subject to a straight tensile pull....where a large head is not needed for appearance, smaller sizes of drive head should be used to decrease the required driving pressures."
Generally smaller heads means smaller shank, the only exception that I know of is BACR15FT rivets, which are reduced head protruding rivets. Basically a 5/32 will have the head of a 1/8. The Van quote talks about rivets subject to a tensile pull, but it has always been my understanding that rivets are shear, not tension, fasteners. So I find it a bit confusing.
 

BBerson

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It's about making it worse by removing imperfect rivets. Here is the full Alcoa Rivet handbook excerpt:




"The standards to which driven
rivets should conform are frequently
uncertain. In addition to dimensions
and perfection of shape, inspection is
concerned with whether the drive head is
coaxial with the shank (not "clinched") and
whether there is excessive cracking of the heads.
It has been determined that even badly cracked heads
are satisfactory from the standpoint of static strength, fatigue strength and resistance to corrosion. (Poorly set and cracked) rivet heads were tested in tension to determine how well formed a head has to be in order to develop full strength. The tensile strengths of all the rivets were within five percent of the strongest. The test indicated that minor deviations from the theoretically desired shape of head are not cause for concern or replacement. The second rivet that is driven in any one hole [is] likely to be more defective than the first because the hole is enlarged and [the] rivet will be more likely to buckle and form an imperfect head. Tests have shown that very small rivet heads are sufficient to develop the strength of the rivet shank, even when the rivets are subject to a straight tensile pull....where a large head is not needed for appearance, smaller sizes of drive head should be used to decrease the required driving pressures."
 

Angusnofangus

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It's about making it worse by removing imperfect rivets.
It's a given that anytime you take a rivet out the hole will be bigger. The saving grace of aluminum rivets is that they will expand and fill that hole, assuming one didn't make that hole too big. At which time one would go for the next size up.
 

BBerson

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Right. The defective rivet hole will be larger if a harder rivet was used than the sheet. That's why I am looking at every detail including finding rivets softer than 6061-t6.
 

Angusnofangus

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Right. The defective rivet hole will be larger if a harder rivet was used than the sheet. That's why I am looking at every detail including finding rivets softer than 6061-t6.
The hole will be bigger no matter what rivet was used. Just the act of drilling out the rivet will enlarge the hole, no matter how careful you are. AD rivets are perfectly acceptable for 6061-T6. Van's says that 2017 rivets are typically used for 2024 and 6061, but I suspect that might be a typo as 2017's are D rivets and D's are a little harder that AD's. D rivets are not usually used in light aircraft, but Boeing uses them by the bucket full.
 

proppastie

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always been my understanding that rivets are shear, not tension, fasteners. So I find it a bit confusing.
There is a tension number.....which comes into use in out of plane forces, buckling etc. The stress guys may need/want that number.

I am looking at every detail including finding rivets softer than 6061-t6.
driven rivets are softer than steel drill bits....a sharp bit will drill the rivet and not walk even if it is slightly harder than 6061-t6
 

BBerson

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I ordered the recommended 6063-t61 from rivetsonline.com.
The shear is 23k. Which is exactly what I want, I think. ( half between soft A at 11k and hard AD at 33 K)
 
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