Rivet like it's 1939

This site is a consistent source of inspiration and entertainment for me but I have only lurked for years since my projects are off-topic. However, the process of riveting aluminum is on-topic, changing little since the 40’s so, as thanks for everything I’ve learned here, here’s a quick tutorial on setting solid rivets.

I found a couple to earlier threads with some useful info and links;
http://www.jalopyjournal.com/forum/showthread.php?t=246122
http://www.jalopyjournal.com/forum/showthread.php?t=141185
Perhaps we can make this thread a single, comprehensive tutorial. Please add information as required.

Riveting with Solid Rivets
The goal is to end up with the manufactured head of the rivet flush against the sheet, zero gaps between sheets, and a concentric shop-formed head with a diameter at least 1.5 times the rivet diameter and a thickness at least half the rivet diameter.


A component I assembled with all the techniques listed below.

Solid Rivets: You will likely use one of two common types, 100-degree countersunk head or universal head in 2117-T4 aluminum. These will have a single dimple in the head designating the alloy. Countersunk heads are designated AN426AD. Universal heads are designated AN470AD. Typical airframe skin rivets are 3/32” (ANxxxAD3) or 1/8” (ANxxxAD4) diameter. Most readily available tools are designed for up to 1/8” rivets. Larger rivets require larger tools. Rivet length is called out in dash numbers in 1/16” increments. For example, an AN426AD4-5 is a countersunk 2117-T4 rivet, 1/8” diameter, 5/16” long. Countersunk rivet length is the overall length. Universal rivet length is the length under the head. The tail of the rivet must extend at least 1.5x the rivet diameter beyond part to ensure a large enough shop head is formed. Too long a rivet will bend over or crack so the shortest rivet that achieves the 1.5d dimension should be used. These rivets are typically purchased by weight.


1/8" universal head rivets (AN470AD4) on left, 3/32" countersunk rivets (AN426AD3) on right.

Hole Prep: 3/32” rivets require #41 or #40 holes. 1/8” rivets require #30 holes. The holes need to be deburred. The parts to be riveted must be clamped - if permitted, these rivets love to expand between the parts.

When using countersunk rivets, thin sheet material must be dimpled rather than countersunk. Dimples can be formed with the appropriate dies in a hand squeezer, a pneumatic squeezer, or if living dangerously, with the dies, some creative scrap metal usage, and a hammer.

In general, for 3/32” rivets any sheet less than 0.032” should be dimpled. For 1/8” rivets, the minimum is 0.040” thick. The minimum thickness increases if the sheet lies under another dimpled sheet. You are simply trying to prevent a knife-edged hole when cutting countersinks. It’s best to back up the sheet with particle board or similar material when cutting countersinks to provide material to guide the cutter pilot. Countersink depth is typically controlled using a “micro-stop countersink cage,” a depth stop adjustable in 0.001” increments. The aircraft rivets are 100-degree, not the more common 90 or 120-degree, so the cutters need to match.

Those with access to a lathe can make their own dimpling tools. Otherwise, countersink cutters, depth stops (a “microstop countersink cage”) and dimple dies are available from a variety of online sources or aircraft tool houses. You may want to buy a spare 3/32” cutter since you will break a pilot early on a Friday night, making you grumpy all weekend and requiring an apology to the wife.


Countersink cage and cutters on left, dimple dies on right.

Riveting with a Squeezer: When access permits, rivets should be squeezed rather than shot (bucked). You’ll get far better results and there really isn’t much chance for error or damage to the part. A smart man will lay out his flanges and order of assembly to ensure as many rivets are squeezed as possible.

Hand squeezers by Townend Aerospace Tool Company (TATCO) are nice tools. A variety of yokes are available. Pneumatic squeezers are significantly more expensive and not worth the money if you aren’t doing this extensively. I own one but still use the hand squeezer first, only pulling out the pneumatic when I can’t reach far enough with the hand squeezer - I have different yokes for the pneumatic tool.

Most hand squeezers have an adjustable ram with which to set the amount of travel. Adjustable rams for pneumatic squeezers can be purchased for additional cost. I use a combination of different length rivet sets and shims on my pneumatic tool. These tools develop the most force at the end of their stroke and it is possible to stall a pneumatic squeezer when compressing long 1/8” rivets. Forget about trying anything larger unless you use of the dual cylinder squeezers.

Squeezing rivets couldn’t be simpler. Insert the appropriate dies in the squeezer, ensure the depth of stroke is appropriate to form a proper shop head, pull against the manufactured head to ensure it is flush against the sheet, and squeeze. Repeat down the line.

Riveting with a Gun: Setting rivets with a gun and bucking bar takes a little more practice and may require second pair of hands, but is pretty simple as well. Rivet guns are NOT air chisels - they have a lower force, slower cycle rate, and sensitive trigger. Rivet guns come in various capacities designated 2X, 3X, 4X. 2X is rated for 5/32” rivets, 3X for 3/16” rivets, and 4X for 1/4” rivets. The hammer force increases with rating while the frequency of hits decreases. I use a 3X for everything.

Good rivet guns have a pressure adjustment in the handle. It is still best to reduce your air line pressure to the 20-30 psi range. If you use full line pressure, the initial gun hit will be too harsh. You’ll need to return that line pressure to 90-psi to use the pneumatic squeezer.

Bucking bars can be any piece of steel of an appropriate shape and smooth face. The bar should weigh between 2 to 3 pounds for 3/32” rivets and 3 to 4 pounds for 1/8” rivets. A wide array of manufactured bucking bars can usually be found cheap in aircraft surplus houses.

Rivet gun capacity, bucking bar weight, and line pressure is not an exact science. You’ll have to dial it in.

Flush rivet sets for countersunk rivets are generally 1-2” diameter with a lightly crowned face. If riveting with a helper, one hand will operate the gun while the other steadies the set. If riveting solo, a flush set with a rubber edge can help keep the set from moving off the rivet head. The set must be kept perpendicular to the sheet or you will create a nice smiley face dent.

Rivet sets for universal head rivets need to be matched to the rivet diameter. The cupped face of the set will dig into the sheet if the set is too large for the rivet, or will dig into the rivet if too small. The set must be held perfectly perpendicular to the sheet or you will damage both the skin and the rivet head.

You insert the rivet into the hole, hold the gun and set against the rivet head to keep it flush, hold the bucking bar against the rivet tail, and squeeze a short burst with the trigger. With some practice you get a feel for how much of a burst to use. Ideally you want to set the rivet all in one burst since they work harden by design.


Hand squeezer in foreground, pneumatic squeezer in background. Rivet gun and sets scattered about.

Screwing Up: If you are building an aircraft, overdriven and other malformed shop heads should be replaced. For hot-rodding, unless it is a critical structural component where a single rivet makes the difference, it’s hard to justify the work to replace a poorly formed rivet unless aesthetics demands the repair. Removing a rivet requires center-punching the head, drilling to the depth of the head for a 1/16” or 1/8” pin punch, using the pin punch to snap off the rivet head, and driving the rivet shank through the material with the punch. If the hole is buggered, you have three options; If it only requires a small amount of clean-up (maybe a drill size or two), you may be able to pre-squeeze a longer rivet of the same diameter to swell the shank. I’ve never been able to make this work satisfactorily. You can use NAS1097 rivets which have a rivet shank one size greater than the rivet head. You can drill out the hole to next size and retain the original countersink or dimple. Otherwise, you’ll need to drill and countersink/dimple to the next larger standard rivet size.

So there you have it. Rivets are cheap but the tools are not. If you have a small project you want to try, look up the nearest chapter of the EAA (Experimental Aircraft Association) here; http://www.eaa.org/chapters/locator/
You’ll likely find a some assistance. One stated goal of the organization is education, after all.

 

I have ZERO need for this info but it is bad ass you took the time to write it all up.

 

Once again thanks for taking the time to pass along that great information. I drilled and removed every rivet in my Model A bed before having all the metal work done. I had rivets and intended to rivet it all back together but I found MUCH nicer gennie sheet and changed directions with my project...

 

Wish I had seen those tools before I put my car togeter. I ended up with pop rivets. They do the job but I had a supply of the original type rivets, small aluminum tube rivets that Chev used in the factory. I tried to do it but they didn't work. I would gladly have paid the price to make it right for the 18 or so I needed to do

 

Thanks a good post

 

Thank you for the education. It is a subject that I have always had questions. This will come in handy on the Airstream project. Off-topic is sometimes a bulls eye. Thanks

 

Thanks for the info.... I've always wanted to know how it's done.

Craig

 

thanks for the info...cool

 

If thats post #2 I want to see post #3!
Thank you

 

The EAA gives hands on classes at the "AIRVenture" show each summer in Oshkosh Wisconsin... I've taken several classes over the past 34 years!

Well worth the price of admission plus many times you can purchase everything you need to complete any task at the "FLY MARKET" on the EAA grounds.

 

Great post-Thanks for the good write up!

 

Very informative post and great write up! Much appreciate the time you put into it.

 

great post. you must work in the aviation industry. at an airline or manufacturer?

 

You have cleared up a few questions I have been wondering about. Great information and a good job well done.

 

Oh crap. Now I have to go build and airplane.

 

Very nice writeup, I had wondered if it was still possible to do when I was looking at the rivets on my old truck frame.

 

OH MAN! Awesome!! Just in time too! I'm about to go on quite a riveting adventure in the next few months! Great stuff!

 

After leaving the Air Force, I went to work for Rockwell here in Tulsa as a Structures Mechanic. I built the inboard leading edge of the 747 wing, and the barrel section of the 757.

Your thread brought back some good memories about rivet guns and bucking bars while I was there.

This makes me want to get back into riveting...

 

Here's some tools I picked up. Probably not the best for the professional, but should be more than adequate for the hobbiest.

I bought this riveting gun set from Aircraft Spruce for $300.
http://www.aircraftspruce.com/catalog/topages/rivgunkit.php



Also picked up 1/8" clecos and the setting tool for them from Aircraft Spruce. The more clecos you buy the cheaper they are. I bought a 100 to start out with just to give it a go and try things out. When I build my roof insert I will need a few hundred more, I'm sure. They are easy to use and pretty inexpensive for how useful they are.

 

Awesome!!!!!! thanks for posting

 

I need to get into that

 

Thanks for the info, i've been fumbling and bunbling with the air gun and bucking bar trying to get it right but the problem is that i don't do it enough to really figure how to get good at it. Now i have a feel for how long the rivets should be to begin with and that'll help bring things together. I think i'll get a set of those hand squeezers, that looks like the ticket for me. Most of what i use that type of rivet is on a dzus spring loaded plate for a hood etcetc and a pull rivet protrudes on the backside to interfere with the spring/receiver plate. Thanks, oj

 

I have a question about micro-stops and counter-sinks....

Just taking a quick glance at what's out there, I see there are quite a few different "micro-stop" countersink "helpers" available. Everything from slim bodied to stops that have a nylon ring so you don't put a ring on your work piece when creating the countersink. Could you (or someone) please expand on what types of countersinks guides/stops are good for various applications? Here's a couple of the types I see:

This one is available with a bronze or needle bearing...



This one has a ball thrust bearing



Only using Aircraft Spruce website for reference. I know there are a TON of companies out there selling and manufacturing this type of stuff. Here's the ACS page where I saw the countersink stuff above:

http://www.aircraftspruce.com/menus/to/countersinks.html

This would be a great thread to list some manufacturers and other sources of tools and supplies as well.

 

Bad ass!

I was wondering how I was going to put those new chains back on my F2 bed...

~Jason

 

very cool tech!!!

 

great post, thanks.

 

Yardstore.com has a good selection of riveting tools and Clecos.

Decent prices and excellent service.

 

great post much appreciated.

 

Nice work, thanks.