Solid Rivet shop head size criteria

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

BBerson

Well-Known Member
HBA Supporter
Joined
Dec 16, 2007
Messages
13,093
Location
Port Townsend WA
Homebuilts are often built with 6061-t6 and some some use 6061-t4. The hard rivets do leave a divot in 6061-t6.
They often use soft 1/8" Avex aluminum rivets (110 lb shear in AC catalog)
The 1/8" soft "A" rivets are 143 lb shear.
Again, that's why I started this thread.
 
Last edited:

Dan Thomas

Well-Known Member
Joined
Sep 17, 2008
Messages
5,278
The soft "A" rivets are not used on certificated aircraft.
Sometimes. Cessna uses them to attach the lead mass balance weights on the ailerons. Using an AD rivet doesn't work, since the lead is too soft to oppose the rivet swelling in it and the rivet will disappear into the lead.
 

BBerson

Well-Known Member
HBA Supporter
Joined
Dec 16, 2007
Messages
13,093
Location
Port Townsend WA
Huh, didn't know about that.
Yeah, we used soft 1100 rivets to assemble the 3003 alloy fuel tanks. The rivets went into the baffles. Then the weldable soft rivets were TIG welded to seal them on the outside.
 

Mad MAC

Well-Known Member
Joined
Dec 9, 2004
Messages
611
Location
Hamilton New Zealand
Looked at the mil spec (MIL-R-47196) for installing rivets 3/16 calls out a 1.3 diameter tail and 0.4D height.

There is some dim glimmer of a thought that somewhere there is a spec that for tails for shear rivets, can be smaller again but I can't think where it was.
 

proppastie

Well-Known Member
Log Member
Joined
Feb 19, 2012
Messages
4,527
Location
NJ
So you are using one diameter stem before driving (for ultralight). Interesting.
Well it depends on length of rivet and what I am riveting....The 1D protrusion is easier to drive but it does not always work out that way with the stack up of parts....I will drive between 1D and 2D with a desired diameter of the shop head of 1.5 D. I use 3/32 AD rivets as much as possible....If I screw up I usually leave the rivet as I figure there are more than enough, they are in shear, and I will screw up the hole trying to remove it......I do remove some though.

No way can you get an acceptable shop head with 1d protrusion
Well maybe I have a little more than 1D...according to the reference 1.3 D will give acceptable shop head....I just eyeball it, and prefer 1.5 D protrusion. But the smaller protrusions are much less likely to tip. It is easy to tip the 2D protrusions.
 
Last edited:

proppastie

Well-Known Member
Log Member
Joined
Feb 19, 2012
Messages
4,527
Location
NJ
I am concerned that the solid rivets are not the ideal choice for the next generation kit builders
Not necessarily....I have seen as per the specifications, the blind rivets are more critical in length and diameter, especially the dimpled flat head holes, and hole diameter. I had to buy the .110 diameter flat head rivets for my LE because the RV dimple tool I borrowed made the hole too large for my 3/32 flat head ss blind rivets.

Had I be able to drive solid rivets the larger holes would not have been an issue. One can cut solid rivets to length if needs be, but otherwise if you do not have the right length blind rivet it is going to cost you in time and shipping costs to get a few of a different size.

All of which may not be of concern to a kit but generally speaking anything other than a kit it may bear consideration.
 

kent Ashton

Well-Known Member
Joined
Aug 15, 2008
Messages
739
Location
Concord, NC
It is important to keep the face of the bucking bar clean and highly polished. When not so, the bar held at a small angle to the rivet (easy to do) will grab rivet through friction and push it to one side or clinch it. A polished bucking bar will also accomodate a bit of lateral movement by the bucker without grabbing the rivet.
 

BBerson

Well-Known Member
HBA Supporter
Joined
Dec 16, 2007
Messages
13,093
Location
Port Townsend WA
But the smaller protrusions are much less likely to tip.
Bigger rivets are much less likely to tip. If the designer chooses bigger than standard and there is enough edge distance. The bigger rivet doesn't need a standard driven head size because it is overkill, and can use a shorter tail.
 

BBerson

Well-Known Member
HBA Supporter
Joined
Dec 16, 2007
Messages
13,093
Location
Port Townsend WA
It is important to keep the face of the bucking bar clean and highly polished. When not so, the bar held at a small angle to the rivet (easy to do) will grab rivet through friction and push it to one side or clinch it. A polished bucking bar will also accomodate a bit of lateral movement by the bucker without grabbing the rivet.
That's correct. But I am looking for other options such as shorter tail so that such expert nuances are not needed for success by a novice.
 

Angusnofangus

Well-Known Member
Joined
Sep 29, 2015
Messages
419
Location
Victoria, Canada
Looked at the mil spec (MIL-R-47196) for installing rivets 3/16 calls out a 1.3 diameter tail and 0.4D height.

There is some dim glimmer of a thought that somewhere there is a spec that for tails for shear rivets, can be smaller again but I can't think where it was.
Rivets ARE shear fasteners. Bolts, Hi-Locs, etc, can be tension fasteners, also can be use in shear.
 

Angusnofangus

Well-Known Member
Joined
Sep 29, 2015
Messages
419
Location
Victoria, Canada
Bigger rivets are much less likely to tip. If the designer chooses bigger than standard and there is enough edge distance. The bigger rivet doesn't need a standard driven head size because it is overkill, and can use a shorter tail.
I don't agree that smaller tails on large rivets are OK. There are standards for tail sizes for a reason. I think it is safe to say that every aircraft manufacturer defines acceptable shop head sizes for every solid rivet, and that they are all within a few thousandths of an inch of each other.
 

Angusnofangus

Well-Known Member
Joined
Sep 29, 2015
Messages
419
Location
Victoria, Canada
Well maybe I have a little more than 1D...according to the reference 1.3 D will give acceptable shop head....I just eyeball it, and prefer 1.5 D protrusion. But the smaller protrusions are much less likely to tip. It is easy to tip the 2D protrusions.
Agree that 1.3 d will give you an acceptable shop head, although 1.5 is ideal. Sometime because of the stack-up you would have to use the shorter length, but still maintain at least 1.3. The longer you get from 1.5, the harder they are to take down without dumping. I've bucked hundreds of thousands, if not millions of rivets and I would dump 99 out of 100 rivets if they protruded 2d.
 

BBerson

Well-Known Member
HBA Supporter
Joined
Dec 16, 2007
Messages
13,093
Location
Port Townsend WA
Van's note said: "there are times ..we have chosen to use a rivet that may seem too short in places, but will do the job adequately."

That's all I need to know, I think. Thanks.
 

Angusnofangus

Well-Known Member
Joined
Sep 29, 2015
Messages
419
Location
Victoria, Canada
Van's note said: "there are times ..we have chosen to use a rivet that may seem too short in places, but will do the job adequately."

That's all I need to know, I think. Thanks.
Not every rivet needs to be textbook perfect, but one should strive for that. That said, the odd rivet that doesn't meet specs is not going to make the airplane fall out of the sky.
 
Last edited:

BBerson

Well-Known Member
HBA Supporter
Joined
Dec 16, 2007
Messages
13,093
Location
Port Townsend WA
Not every rivet needs to be textbook perfect, but one should strive for that. That said, the odd rivet that doesn't meet specs is not going to make the airplane fall out of the sky.
I am not suggesting sloppy work. Rather, I am exploring alternative specs or methods to improve success with limited tooling. Otherwise the builder might choose a less desirable build fastener. The Military specs are interesting but don't legally apply to homebuilts and ultralights. So other standards and specs can be considered or created for unusual structures.
 

Mad MAC

Well-Known Member
Joined
Dec 9, 2004
Messages
611
Location
Hamilton New Zealand
Interesting to note that the NAS1097's have better hole filling than MS20426 rivets (I think there is also an LS spec rivet that has even better hole filling).

The problem with using something else to join aluminum is that solid rivets have the lowest hole tolerance requirements and one of the cheapest fasteners.

So what you actually want is those explosive rivets (never ever seen one though). Apply head source to heat, and it cooks the tail off, build an aircraft and get your pyro fix at the same time.

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).
 
2
Top