Solid Rivet shop head size criteria

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BBerson

Well-Known Member
HBA Supporter
The usual recommendation for the shop head is to use a rivet that extends 1.5 times the diameter. See here:How to select the correct rivet size atlascopco
But it's much easier to drive when the rivet is less than that recommended 1.5 times the diameter.
I don't see how it would make too much difference in strength. So my question is if there is any data or criteria about using a smaller shop head thickness? I shot some at 1.0 times diameter and they looked fine. But didn't load test them. However, it seems to me that almost any size shop head is equivalent to a flush head....
And does the DAR inspect for this rivet criteria?

Turd Ferguson

Well-Known Member
I think if the rivets were loose and/or falling out when you shake the aircraft a DAR "might" say something but otherwise, nah they not going to worry with that. They'd rather scrutinize placards.
I put some rivets in a project the other day and the only length I had were ~1-1/4d for the shop head. They worked fine - I smashed the crap out of em.

BBerson

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HBA Supporter
I had were ~1-1/4d for the shop head. They worked fine - I smashed the crap out of em.
I think I will aim for 1-1/4d also.
My Alcoa books said the rivets should be same alloy or softer. Since the standard 2117-t4 rivets are harder than the 6061-t6 I am using, driving them too much expands the hole too much and could crack the part.

Kyle Boatright

Well-Known Member
Bill, I'm not exactly sure I follow you. If you're driving a 1/8" rivet, I don't see how you drive it such that the shop head is the same diameter as the original rivet shank diameter, which is my interpretation of what you wrote. For that 1/8" diameter rivet, the shop head should be 1.5x 1/8 = 3/16" in diameter. It almost sounds like you're trying to drive your shop heads to 2+ times the diameter of the rivet shank.

My apologies if I'm misinterpreting your post.

Tiger Tim

Well-Known Member
When I learned to rivet the goal was shop head widths of 1.5 x the shank diameter and shop head thicknesses of 0.5 x diameter. Length was adjusted to whatever it took to achieve that but usually material thickness plus 1.5 diameter or thereabouts.

BBerson

Well-Known Member
HBA Supporter
Bill, I'm not exactly sure I follow you. If you're driving a 1/8" rivet, I don't see how you drive it such that the shop head is the same diameter as the original rivet shank diameter, which is my interpretation of what you wrote. For that 1/8" diameter rivet, the shop head should be 1.5x 1/8 = 3/16" in diameter. It almost sounds like you're trying to drive your shop heads to 2+ times the diameter of the rivet shank.

My apologies if I'm misinterpreting your post.
The shop diameter should be 1.4 (according to link above)
I was referring to the unbucked shank stick out length. A shorter stick out length results in a thinner shop head.

BBerson

Well-Known Member
HBA Supporter
When I learned to rivet the goal was shop head widths of 1.5 x the shank diameter and shop head thicknesses of 0.5 x diameter. Length was adjusted to whatever it took to achieve that but usually material thickness plus 1.5 diameter or thereabouts.
Yes, that's the recommended goal of Type certificated aircraft. Sometimes difficult in a home shop when the rivet work hardens before fully setting.
I am looking at options to help make solid rivets more desirable, instead of builders choosing pop rivets instead.

pwood66889

Well-Known Member
Only good experience I had with solid rivets was setting em with a squeezer.

BBerson

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HBA Supporter
Only good experience I had with solid rivets was setting em with a squeezer.
Yeah, that's a sad state of affairs. That's why I want to improve the options. A squeezer doesn't work for most situations. And my goal with my design is for all the solid rivets to be set by one person with a small rivet gun. It is an open frame truss with easy access.

Angusnofangus

Well-Known Member
My Standard Aircraft Handbook give the following criteria for 1/8 rivets; diameter 7/32-11/64, and height 3/64-5/64. That would be for aluminum rivets. Monel rivets would be less as you only want protrusion of about 1D, or they will dump. I have some go-no go gauges around here but never used them. When I worked in manufacturing we had specific tables for shop head size and inspectors would measure any suspect tails with calipers.

Angusnofangus

Well-Known Member
Yes, that's the recommended goal of Type certificated aircraft. Sometimes difficult in a home shop when the rivet work hardens before fully setting.
I am looking at options to help make solid rivets more desirable, instead of builders choosing pop rivets instead.
I don't feel that work-hardening is a problem with smaller rivets, as they are pretty easy to take down. !/4 inch rivets, yes, and 3/16, maybe. But 5/32 and smaller, not in my experience.

Angusnofangus

Well-Known Member
Yeah, that's a sad state of affairs. That's why I want to improve the options. A squeezer doesn't work for most situations. And my goal with my design is for all the solid rivets to be set by one person with a small rivet gun. It is an open frame truss with easy access.
IMHO the best all-around rivet gun is a 3X. Sometimes space might call for a 2X, but I always disliked using one except for when nothing else would fit the space, and then they are only good for 1/8 rivets. At one place I worked we had a 2X sized Copco that would easily drive 5/32's. Only thing was, it was an \$800 rivet gun.

Well-Known Member
Note that fatigue performance of a driven rivets is set by how well they fill the hole and this is related to the amount of force used to drive it*. The amount of deformation the rivet deforms has a rough corresponance to the amount of hole filling. Tails under 1.5 are likely to have poorer performance, both in shear and fatigue.

* If one bored look up over driven rivets their fatigue is 10x hand driven

BBerson

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HBA Supporter
I don't feel that work-hardening is a problem with smaller rivets, as they are pretty easy to take down
Is that with a helper to buck? More tricky to hold the gun and bar both without messing up.

BBerson

Well-Known Member
HBA Supporter
Note that fatigue performance of a driven rivets is set by how well they fill the hole and this is related to the amount of force used to drive it*. The amount of deformation the rivet deforms has a rough corresponance to the amount of hole filling. Tails under 1.5 are likely to have poorer performance, both in shear and fatigue.

* If one bored look up over driven rivets their fatigue is 10x hand driven
I am looking at next size larger than needed (5/32") with a proper hole size.
Also have some 3/16" 6053 rivets on order to test.

Angusnofangus

Well-Known Member
Is that with a helper to buck? More tricky to hold the gun and bar both without messing up.
I don't feel that it makes any difference, helper or not. As long as I could reach it, I could usually shoot and buck.
But then I did it for 28 years and probably a couple of million rivets.

N804RV

Well-Known Member
HBA Supporter
Yes, that's the recommended goal of Type certificated aircraft. Sometimes difficult in a home shop when the rivet work hardens before fully setting.
I am looking at options to help make solid rivets more desirable, instead of builders choosing pop rivets instead.
I had trouble with work-hardening rivets. Turns out, my cheap 2X rivet gun just didn't hit hard enough or fast enough to set the rivet. I went with a good quality ATS Pro 3X gun and set line pressure to 90psi, then dialed the end pressure down so that I could set an AN470-3 rivet a very short squeeze, slightly lest than a second. I dial the end pressure up 1 click and it takes maybe 1 or 2 more hits to get the same results with a -4 rivet. An old tin bender and (well known) retired Reno crew chief is the guy that set me straight.

BBerson

Well-Known Member
HBA Supporter
I have an old muffler cutter air hammer. Might try that tomorrow. Thanks

Angusnofangus

Well-Known Member
I had trouble with work-hardening rivets. Turns out, my cheap 2X rivet gun just didn't hit hard enough or fast enough to set the rivet. I went with a good quality ATS Pro 3X gun and set line pressure to 90psi, then dialed the end pressure down so that I could set an AN470-3 rivet a very short squeeze, slightly lest than a second. I dial the end pressure up 1 click and it takes maybe 1 or 2 more hits to get the same results with a -4 rivet. An old tin bender and (well known) retired Reno crew chief is the guy that set me straight.
Good advice. I've worked with guys who would use a 4X gun to shoot 1/8's, the logic being that you hit the rivet harder for less time.

Angusnofangus

Well-Known Member
I have an old muffler cutter air hammer. Might try that tomorrow. Thanks
Air hammers are not the same as rivet guns, you don't have the control that the teasing trigger of a proper rivet gun has. I have a spare 3X gun that I would let you have cheap. PM me if interested.

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