Dimple Dies - 1/16" Countersunk or 3/32nds NAS1097

[Kyle Boatright]

I'm looking for dimple dies for either 1/16" countersunk rivets or 3/32" NAS1097 reduced head rivets.

Has anyone ever come across such a thing? If so where?

What I'm doing involves 0.020 aluminum, which is too thin to countersink, even for these rivets.

[TerryWighs]

Is it possible to just adjust the 3/32 dimple die "shallow" ?

[az_gila]

Originally Posted by Kyle Boatright

I'm looking for dimple dies for either 1/16" countersunk rivets or 3/32" NAS1097 reduced head rivets.

Has anyone ever come across such a thing? If so where?

What I'm doing involves 0.020 aluminum, which is too thin to countersink, even for these rivets.

...of a NAS1097-3 rivet is 0.021 inches.

You should be able to countersink this if you are careful and perhaps use a clamped backing piece for the countersink pilot.

As a comparison, the head height for a 426 standard countersunk rivet is 0.036 inches and folks use these countersunk in 0.032 sheet.

http://www.hansonrivet.com/w06.htm

I would presume this isn't a structural part...

[rocketbob]

No problem with .020 material and countersinking for 1097 rivets..they have a slight dome to them that helps them expand into the countersink. Wish standard rivets had this feature.

[Kyle Boatright]

Originally Posted by az_gila

...of a NAS1097-3 rivet is 0.021 inches.

You should be able to countersink this if you are careful and perhaps use a clamped backing piece for the countersink pilot.

As a comparison, the head height for a 426 standard countersunk rivet is 0.036 inches and folks use these countersunk in 0.032 sheet.

http://www.hansonrivet.com/w06.htm

I would presume this isn't a structural part...

Your presumption is correct. I'll give countersinking a shot, but would still prefer to dimple this stuff.

So if anyone has a source for the dimple dies, lemme know...

[roee]

Kyle,

Out of curiosity, what are you doing?

And if you have room around and behind those rivet locations, which presumably you do if you can dimple there, then what's your motivation for using NAS1097 rivets rather than standard AN426 rivets?

Just curious.

-Roee

[Kyle Boatright]

Originally Posted by roee

Kyle,

Out of curiosity, what are you doing?

And if you have room around and behind those rivet locations, which presumably you do if you can dimple there, then what's your motivation for using NAS1097 rivets rather than standard AN426 rivets?

Just curious.

-Roee

The application is rib repairs on an Aeronca Champ. On a Champ, the fabric is attached by little bitty screws going into the ribs. If I recall correctly, the holes are drilled #44. The problem is that after 60 years or so and mulitple recoverings, the screws enlarge the holes. The common repair is to rivet little aluminum backing plates behind each wallowed out hole, then redrill to #44.

The original ribs are 0.020, and have a very narrow flange, so my goal is to remove as little material as possible when I drill holes to attach the backing plates. With that in mind, dimples are preferred to countersinks...

[roee]

Originally Posted by Kyle Boatright

The application is rib repairs on an Aeronca Champ. On a Champ, the fabric is attached by little bitty screws going into the ribs. If I recall correctly, the holes are drilled #44. The problem is that after 60 years or so and mulitple recoverings, the screws enlarge the holes. The common repair is to rivet little aluminum backing plates behind each wallowed out hole, then redrill to #44.

The original ribs are 0.020, and have a very narrow flange, so my goal is to remove as little material as possible when I drill holes to attach the backing plates. With that in mind, dimples are preferred to countersinks...

I think you're correct that dimpling will leave the structure stronger than machine countersinking. But I'm still not picturing why you can't use standard AN426AD3 rivets. Whether you use NAS1097 or AD426 rivets, you're talking about using a 3/32" diameter rivet. Right? So the hole size (material removal) is the same, only the dimple size is different. And if the rib flange is at least wide enough to meet the edge distance requirement for a 3/32" diameter rivet, which it better be in either case, then it's also wide enough to accept a dimple for a standard rivet. Maybe I'm missing something..? Anyway, good luck!

-Roee