MIMF

Hey, I'm making truss rods for the guitars I'm building now, and at the hardware store I saw a selection of "music wire". 3' sections, and the largest diameter was 3/16".
Oh! Perfect I say - a music wire truss rod. That sounds fitting. So I buy a 3' piece and start at it.
I use a single action, simple rod with nut at the headstock. So I bend an "L" on the end to anchor it. No problem. The usual propane-torch-hammer-it-over does the job.
Then I cut it to length, grind the end clean, and start with a threading die.

Holy Moly - this stuff is tough!! I've not gotten 1/2" of threads and it has already eaten 2 dies! The dies don't even cut chips, they have to mow through the metal, they get hot, and the cutting edges break off. Yikes!

So I look it up, and music wire is 1080 or 1085 carbon steel that is usually at "spring temper". Oye!
I take the torch to it to anneal the end I'm threading. Then I can just BARELY finish cutting the threads, so this rod is not a waste, but ...

Back to cold-rolled steel for me.

So now you have a truss rod that is hardened everywhere except at the threaded end? I think I would prefer something that has a little "stretch" along the whole length for a truss rod.

Hey Clay, it's hardened to a spring temper. It's tough, but it won't shatter like a piece of glass. Springs do a lot of stretching.

I learned this lesson but with a geometric die head which cost me a bundle to replace the chasers on.
I'm sticking with O-1 oil hardening drill rod which threads like a dream.

So David, I also have some O-1 and it was not easy to thread.
It's from McMaster-Carr THIS stuff.
It says in the state you get it it is Rockwell B89. Apparently, pretty hard, based on my experience.
Do you treat it, or do you buy different stock that is fully annealed??

At about $10-15 for the uber-reliable and very responsive aluminum U channel "Martin style" truss rod, why even bother making your own? I'm all for making as much of the instrument in house, but this is one place I cannot see the value or reasoning.

Hey Mario, I like the simple compression rod. Nut at the headstock.
Just a single rod of 3/16" steel up the neck, nothing more.

You can turn the U channel rod around and adjust at the headstock....

Oh yea, I'm aware of the options. It's just not in the cards right now.
Thanks tho...

What pupose was the wire at the store intended? Were they expecting people to buy this to make a childs piano?

Hey Steve, that sounds like a joke, but I'm going to answer anyway.
The store I was at is Marshall's Industrial Hardware in San Diego. It is an awesome hardware store. They have many different materials available in round rods: cold rolled steel, stainless, brass, aluminum, O-1 steel, music wire, etc.
People use music wire for all types of applications where they need a stiff, spring-y wire. Like landing-gear on a model airplane.
This stuff would be a major b!tc# to bend into a toy piano.

It sounds really specific, but a quick google tells me that music wire - aka, piano wire - is basically just spring steel. It's made through a cold drawing process, which yields very consistent diameters, and (if I understand correctly) the manufacturing process was discovered through a sort of arms race to produce stronger piano string wire in the 1800s. While it comes in diameters larger than what is used in piano strings, as Chuck's purchase demonstrates, a product that is the result of cold drawn, spring temper, high carbon steel is still known as piano or music wire.

Bingo! That's the stuff.

Look for 'cold rolled' steel round stock (rod), not cold drawn. It's inexpensive, easily machined (threaded), and strong.

Sizes of 3/16" or less are typically referred to as "wire" as opposed to rod. They also come in giant spools as a result. Welding rod comes in 36" lengths and several formulations of stainless are also available cheaply if desired.

The Jaymar and Shoenhut pianos have "musical wire" hit by a small hammer as the tone producing mechanism.

Regarding the hardness of drill rod and the ease of threading I'd recommend that the DIY folks equip themselves with a high speed steel adjustable "split die" and an appropriate diestock. These dies will hold up much better especially when you use a good cutting oil. The split die can be opened up for a shallow cut on the first pass and gradually be closed until you hit the correct thread diameter in subsequent passes. The solid carbon steel dies you see at the hardware store are really "thread chasers" and aren't intended to cut full threads in one pass.

Thanks for the clarification Steve - I see pictures from a Google search now. Nice musical instrument geek reference!

Thanks for the tip David. In all my years of cutting threads I've only used a lathe, or round or hex dies. I've seen the type with adjusting "jaws" but haven't ever used one.
I miss cutting threads on a lathe - that is a very Zen process.

Don't confuse tempered spring steel wire with music wire. The cold forming process for music wire results in wire that has a limited stretch- it will stretch and stay there, under tension. If you anneal it anywhere, that annealed spot can continue to stretch- until it fails. Now, the failure could be at about the same tension as a regular mild steel truss rod of the same diameter, and that might not be so bad. But that one weak spot in the music wire will give you something less than regular music wire tensile strength of around 300 pounds per square inch.

Correct me if I am wrong, but I think the tensile strength is (around) 300,000 pounds per square inch.