The Stovebolt Site Forums The Shop Area Paint and Body Shop Take Me to Rivet School

I need to fasten the two halves of this vintage 1930s/1940s Detroit Products #123 signal arm together. They came to me separated, w/o the original fasteners, in a rusty condition. From an original photo, it appears that the fasteners used were a smooth, round head rivet on both sides (“double-cap” rivet)? The hole diameter is 3/16”. The thickness of the two halves together is approximately 3/16”.

In addition, the name badge appears to have been fastened with the same type of smooth, round head rivet. The hole diameter is also 3/16”. The thickness of those two halves together is approximately ½”.

Can someone help me identify what was used originally in this particular application, as well as source the replacement fasteners and the setting tools required?

Thank you.

LUKE

For putting your two halves together I would use hockey helmet screws they have them in different lengths and you can take them out if you need to .I will post a picture.I think Brad Allen has the same signal on his truck.

Those are called "sex bolts".

It looks like from this link that they originally may have used semi-tubular rivets. That would be the easiest type to put them back together with. You can get those in various sizes from Hanson Rivets in LA. They also sell setting tools for them.

It looks like finding the reflectors that go in the arm will be harder to find than rivets. Hope you can get it restored. I remember those on school busses and trucks when I was a kid.

These signals are called semaphores. Very common on vintage VW's. Semi tubular rivets are for joining where movement is desired. Tubular rivets are what you want. No special tools needed. Hammer and some kind of mandrel. Buy enough to test and perfect your method.
These may work with This tool. Don't know the size of these rivets. I have some but don't know where they are.

We make up the "set" and the "buck" for custom rivet jobs but be aware that solid rivets are hard to get correct free hand. The semi tubular are more forgiving.

I have some of those too. They'd be too small for the 3/16" hole.

I may have some that would work for the perimeter of the arm. Shoot me a PM.


Agree. I've used solid rivets for the frame attachments, and tubular for the hood halves. May also try the tubular rivets for the grille. An assortment of tubular rivet sets was about $6-8 from Amazon.

I need to edit my opinion. Semi tubular rivets are for joining where movement is required or allowed. Not for a tight clamping, Tubular rivets are what you need for this part. Aluminum tubular rivet. A solid rivet requires much more force, you are liable to damage the semaphore and they are not necessary for this type of assembly. Brass will work also. both softer than steel or SS.
If you want easy DIY and don't care about originality, use pop rivets.
A short semi tubular rivet will be like a tubular rivet anyway. The problem is that when the hole in a semi rivet is not at the right depth, it won't upset right for your grip length, The rivets are sold with a grip length range not exact.
Another thing is you have to buy a 100-150 at a time unless Ace or someone has them.

It's kind of semantics. Here's a description from a website I found:
"Steel tubular rivets are similar to solid steel rivets with the exception that they have a hollowed tip at the end of the body, and therefore require less force for installation. Tubular rivets are used to permanently join two materials and can be installed by hand with a manual squeezer or with a rivet gun. Steel semi-tubular rivets only swell at the tail, making them ideal for installation along pivot points." But Hanson doesn't differentiate between semi-tubular and tubular.

I have steel tubular rivets, 3/16 dia x 4.5mm (0.177 in). They're suitable for two thicknesses of sheet metal. They cost me $15 for a bag of 100.

I am getting a good lesson in rivet school--thank you. I want to maintain originality. I also want to properly source them and properly install them.

I do have all the original parts used with this entire assembly arm unit, from the inner cab ratchet control handle, a small piece of the old 3/32" cable, all the way out to the outer control arm and mounting bracket. I have the 8 sun-bleached amber/yellow Stimsonite #15 reflectors as well. I have a separate post on reconditioning the reflectors in General Talk.

I have been in contact with Brad Allen. He states that the rivets on his signal arm are a painted smooth round domed head on both sides.

I have been able to connect with the guy who broke down the main signal arm that I am now reconditioning. He did this about 10 years ago. He said if his memory is correct, he referred to the rivets as "blind rivets" with the nice side in the front. He does remember having to drill them out from the backside. The front head of the rivet was NOT painted. So if all this holds true for this signal arm I am reconditioning, can you set me straight on what rivets I should be using to replicate the look? It sounds to me like it was a standard pop rivet, placed with a common pop rivet gun. This is different from what Brad Allen described.

I have sent a PM to Klhansen.

Please keep pointing me in the right direction. This project is currently keeping me out of trouble. THANKS!

Luke

For the sake of getting this info out to everyone who might be interested, here's the PM I sent to Luke:

You could use solid steel rivets on you signal arm, but they may need to be installed HOT and peened over with a tool with the right shaped cavity. They may have used them on your arm, but based on the one I found on eBay, it looked like they changed to tubular rivets at some point during production, as the tubular rivets can be installed cold. They use a setting tool that has a cavity with a small central protrusion that expands the tubular portion of the rivet and then curls it back to the outside to fasten the two pieces of metal together.
With solid steel rivets, they have to be just the right length for the thickness of the material so there's not excess material when forming the head from the shank of the rivet that goes thru the hole. Tubular rivets also need to be the correct length for the material.
Hanson Rivet also can provide solid steel rivets. I have actually made a rivet for the frame repair I needed to do out of a bolt. I just ground the hex head to the rounded shape, but that would be a pretty tedious task for the number of rivets you'd need.
Here's a link to solid steel rivets at Hanson Rivet. Link There's a lot of info on that site if you browse around.
I remember learning to rivet things in my dad's sheet metal shop. I think they were about 1/8" diameter and were set cold. Larger sizes would probably need to be set hot. The little ones were a 2 step process, first upsetting the diameter of the rivet just a bit to fill the holes in the material, then using a deep hole on the rivet set to push the two pieces of sheet metal tightly together, and then forming the head with a domed shape depression in the rivet setting tool. The tool looked similar to this: Link
If you'd like, I could send you 10 or so of the tubular rivets I have to experiment with. I really think you'd be better off using them as opposed to solid steel rivets. Also, who's going to know they aren't EXACTLY like the originals. Also, I think pop rivets would look completely wrong.
Here's the rivet setting tools I bought from Amazon. Link You can see the shape of the tool for setting tubular rivets. And there's also sets for domed head solid rivets. You also need a bucking bar for the opposite side of the assembly. Any large piece of steel will do for that, either with a depression for the head of the rivet or flat.

Maybe with math, or empirically, you could experiment to get the proper clamp and the "look" by drilling the hole in the rivet deeper and/or cutting the length to find the right combo and create a perfect custom tubular rivet. After all, you will have a 100 of them.

Hanson Rivet's tubular rivet page has some info on length and clinch allowance. It's pretty straightforward. Measure the thickness of the two pieces of material, add them with the clinch allowance gets you length. If they don't have that length on stock, you might need to order 100,000 of them and wait for them to manufacture them.
I don't know what their minimum quantity is, but I bought 100 of the ones I ordered, just to have plenty.

Mission accomplished! This morning the local airport aviation mechanic used solid head aluminum alloy rivets on the arm. The name badge is fastened with aluminum binding posts. The entire assembly is all there, either original or new/improved. I will install this coming April/May and provide an update at that time. Thank you to all who provided guidance on this project--it is greatly appreciated!

Looking good!

There are several sizes and quantities of brake lining rivets available on Ebay. One method of joining parts such as knife scales on custom blades is to use two different sizes of brake rivets so one is a snug fit into the hollow shank of the other one, and peen the two together with a hammer and punch. That's not the proper way to use them, but the result is a tight, permanent installation.
Jerry

NIce looking turn signals. impressive work.

This signal arm restoration project is now complete. It is time to get “my old buddy” back on the road to enjoy the pleasures of driving this time machine. Enjoy the new driving season everyone!