Changer axle

[Ivan Funk]

Question for metallurgy gurus:
I'm using W1 tool steel rod for a new push pull changer replacement axle.
Is this hard enough for wear resistance or does it need to be heat treated?

Old worn axle and new axle:

[Wayne Brown]

I just use the same thing here that i pick up from the local medal supply shop...it's not like its spinning at 3600 rpm and also think on how long it took the old one to become like that. I had 2 carters i re did just recently and there both around the 2000 year mark. So with that said it took 23 years for those grooves to appear like yours. and only on the E9th neck as the C6th wasn't used as much
I hope this helps
thanks
wayne

[Ivan Funk]

Thanks Wayne.
Good point about the years it took to wear grooves.
The old one is from 1974 so almost 50 years.

I guess another way to ask the question is: did Emmons heat treat the drill rod they used for axles or not? Who would know?
If they didn't, then this new axle is a direct replacement and is good to go for another 50 years.

I know I could have just rotated the old one 180° but it is satisfying how little play there is now with the new one.

I'm guessing there is a big hardness difference between Rockwell B95 and C65 but hope that B95 is fine for this application.
Here are the specs of the rod I used:

[Wayne Brown]

Should last a long time. Longer than me on this earth lol
Thanks
Wayne

[Ivan Funk]

Thanks Wayne,
On a related note - I might order a few more parts from you to add a 5th knee lever when I put this thing back together.

[Wayne Brown]

copy that
thanks
wayne

[J D Sauser]

When I was in Tech-U. in Switzerland…. too many years ago, one of the many rules we were taught was which metals do and which do NOT “run” well on each others.
While steel on cast iron “runs” Ok on each other, and steel on steel can be “acceptable” provided good lubrication, aluminum on just about anything (including steel) is a definite “hell NO!”. aluminum really “runs” on nothing without sooner or later binding or ripping.
Most steel manufacturers do not seem to have attended the same school and our instrument is littered with mainly aluminum moving on steel or worse aluminum counter parts, all with the predicted wear and tear. 90’s Sierra Sessions even had aluminum rods clamoed into aluminum “clam” brackets for “quick” leg attachment. Not only did the aluminum clam-brackets lack the necessary elasticity to operate properly, but the shafts became known to bind and get hopelessly stuck in the fatigued clam-brackets.

We took apart a ZumSteel (one if the better built PSGs) a few years ago which had served 20 years as a daily practice beedroomer in sn climate controlled non-smoker environment. A very comfortable life. The changer fingers were worn out and the steel axle had tear marks under both, the steel scissors and the aluminum changer fingers as well!
We hat to replace both, the shaft and the changer fingers.

I personally used heat treated steel shafts with brass changer fingers on my prototype PSG projects. I don’t have a “good” idea for the steel scissors.

In other words, I don’t have a good recommendation but it’s not so much about the steel type of the axle as it is -in my opinion- about the type of aluminum or material of the changer fingers… JD.

[Ivan Funk]

Thanks JD. Great info.
Yeah aluminum on steel is not good.

If I was a builder I'd look into brass bearing inserts in aluminum fingers. Has anyone done that? Or maybe bronze Oilite?

As for this project I'm trying to rebuild it to the original Emmons push pull design. Hopefully non heat treated is the way they did it originally...

[Ivan Funk]

Fingers cleaned up and assembled on new axle:

[Sonny Jenkins]

Paul Redmond put me on to ejector pins,,,McMaster-Carr,,,,,VERY HARD,,,,and precision polished!!!

[J D Sauser]

Thanks JD. Great info.
Yeah aluminum on steel is not good.

If I was a builder I'd look into brass bearing inserts in aluminum fingers. Has anyone done that? Or maybe bronze Oilite?

...

Aluminum on pretty mucch anything ain’t good. Even on nylon/delron too much gap is required for it not to bind.

Since this is not high “rpm” over long runs generating heat etc., yes, the proper way to do this in precision mechanics would be pressed in brass bushings. A steel built like this receiving proper care would outlive most any teenage players live.
But many guitars using large diameter unsupported shafts have too large of a bore in their fingers and scissors to press a bushing in and leave enough “meat” on the swiveling part

When we look at Bigsby, to Shot Jackson over that “physics professor” in NC… there is a LOT of “hillbilly-tech” which has become the accepted and copied over standart in “steel guitar mechanics”, even by quality builders. Some is even defiant of basic teachings of physics. And much is 180 deg. opposite to basic mechanical applications taught in the industry for over 300 years (see my thread about the “automates” (early robots built by watchmakers in the 1700’s) and then turn over your steel and wonder “what happened?!” ).

… JD

[Ivan Funk]

Sonny Thanks for the tip.
I looked into ejector pins. McMaster Carr doesn't have 9/16" pins. The drill rod I used is precision ground so the tolerance is perfect. It was easy to polish. If the surface isn't hard enough - my rationale will be - it's easier to replace the axle every 20 years than locate new fingers.
J.D. Good points. For me part of the magic and charm of the older pedal steels is the alternate universe physics involved in some of the design. It works!
I will continue to research the ancient art of Emmons metallurgy.

[Bobby D. Jones]

From what it says on that spec sheet the rod is annealed.

All Tool Steel, Also commonly called Drill Rod is annealed.
So it can be threaded, Holes, slots or keyways can be machined into the part.

Then be heated to a certain temperature, Quenched in oil or water to be hardened, Then Heat Soaked in an oven to reduce brittleness and make it tough.

I would worry more about the annealed soft rod bending under the string pressure more than I would about the fingers wearing the rod.

[Ivan Funk]

Thanks Bobby.
Yes annealed for cutting, shaping etc...
Do you know if the original Emmons axles were heat treated and tempered?
I guess I can always ask one of the Emmons experts...

[Andy DePaule]

When I was in Tech-U. in Switzerland…. too many years ago, one of the many rules we were taught was which metals do and which do NOT “run” well on each others.
While steel on cast iron “runs” Ok on each other, and steel on steel can be “acceptable” provided good lubrication, aluminum on just about anything (including steel) is a definite “hell NO!”. aluminum really “runs” on nothing without sooner or later binding or ripping.
Most steel manufacturers do not seem to have attended the same school and our instrument is littered with mainly aluminum moving on steel or worse aluminum counter parts, all with the predicted wear and tear. 90’s Sierra Sessions even had aluminum rods clamoed into aluminum “clam” brackets for “quick” leg attachment. Not only did the aluminum clam-brackets lack the necessary elasticity to operate properly, but the shafts became known to bind and get hopelessly stuck in the fatigued clam-brackets.

We took apart a ZumSteel (one if the better built PSGs) a few years ago which had served 20 years as a daily practice beedroomer in sn climate controlled non-smoker environment. A very comfortable life. The changer fingers were worn out and the steel axle had tear marks under both, the steel scissors and the aluminum changer fingers as well!
We hat to replace both, the shaft and the changer fingers.

I personally used heat treated steel shafts with brass changer fingers on my prototype PSG projects. I don’t have a “good” idea for the steel scissors.

In other words, I don’t have a good recommendation but it’s not so much about the steel type of the axle as it is -in my opinion- about the type of aluminum or material of the changer fingers… JD.

I have a Promat built in Serbia. It's a copy of an Emmons with metric parts.
One thing he did as a lifelong machinist was that he milled the fingers from Stainless Steel.
Seems to be built better than some of the Emmons that I've seen though I don't have much experience with push pull steels. It has very smooth action,
I don't know about the new Emmons company or the materials they use, but they seem to be doing a fine job.

[Mark McCornack]

The idea of using a bronze bushing insert in the finger makes so much sense, I wonder why this isn't just the universally accepted method. Regardless of whether this is aluminum finger on a steel axle, or steel on steel (or al on al, for that matter) a bronze bushing would clean that interface up. I recently saw a home built steel in this section where the builder had just such inserts in place. Very nice job, but I can't for the life of me find the thread again.
The bushing wall thickness need not be all that much to do the job, and even if an insert is pushed in and then broached to fit the axle, it seems like it would be worth the trouble. Maybe I'm wrong, and this is too labor intensive to be practical for volume manufacturing, but it sure seems like it would be worth the trouble. Any thoughts on that

[Ivan Funk]

Thanks Mark,
I'd like to see pictures of the bronze bushing insert build if anyone finds it. Sounds like a great idea.

Andy - Your Promat looks great. There are some discussions about the tone difference between aluminum fingers vs stainless steel. I know that GFI started out with aluminum and then switched to stainless steel at some point. I gave an early GFI U12 with aluminum fingers. I've never had a guitar with stainless so I don't know what the difference in sound is. I can see how it would wear slower though.

[Andy DePaule]

Andy - Your Promat looks great. There are some discussions about the tone difference between aluminum fingers vs stainless steel. I know that GFI started out with aluminum and then switched to stainless steel at some point. I gave an early GFI U12 with aluminum fingers. I've never had a guitar with stainless so I don't know what the difference in sound is. I can see how it would wear slower though.

I've never owned an Emmons so I can't really compare.
However, Lynn Stafford who did set up my Promat stated that the fingers do make some difference in the tone.
All I can say is my Promat sounds great and the sustain is very good. I think the PU's are Wallace, but not sure.
After Lynn did the set up I didn't need to touch the tuning adjustments for over two years.
When I did it was just to tune the second string a tad and that was more than a year ago. Same strings since he did it.
Just a very well made steel.
I bet if someone put a Emmons logo on it many would not know, but that would be bad ethics to say the least. The mica is nice but not what you see on Emmons..

[Mark McCornack]

@Ivan. - I found the reference on the bronze inserts. It wasn't on the Forum at all, but on a YouTube I ran across called "Pedal Steel Build & Play" by Scott Finch. In the video, he talks about getting the wood to build the steel from a piece of Mahogany that washed up in a hurricane at his home in Florida! Hard way to get parts

Here's a link to the video
https://youtu.be/Q1XvCbNpFz0

Here is a still from the video showing a finger with insert.

[Ivan Funk]

Thanks Mark.
Very cool.

[J D Sauser]

From what it says on that spec sheet the rod is annealed.

All Tool Steel, Also commonly called Drill Rod is annealed.
So it can be threaded, Holes, slots or keyways can be machined into the part.

Then be heated to a certain temperature, Quenched in oil or water to be hardened, Then Heat Soaked in an oven to reduce brittleness and make it tough.

I would worry more about the annealed soft rod bending under the string pressure more than I would about the fingers wearing the rod.

Just to clarify for those who read along without commenting:

HEAT TREATING "HARDENING""
Heat treated steel is heated to glowing red and rapidly "shock"-cooled down in cold water or cold oil. The molecular structure changes to extremely hard but also brittle. Steel treated like that won't permanently bend anymore and will instead break leaving a brake-section that seems "porous".

ANNEALING:
To mitigate this in some cases and retain reasonable "hardness" with less risk of breakage or chipping, heat treated ("hardened") steel can be reheated to some oxidation colors (brown, yellow or ALMOST blue) to soften it back some. If you pass blue, the hardening of the previous heat treatment will be all but gone.
This post-heat treatment is called "annealed".

I DOUBT heavily that a heat treated un-annealed shaft of the typical diameters used on changers only supported on the ends would break under the string's and their changes' tension. It would just be very unlikely to bend or "give"... a phenomenon often suggested in steel guitar circles to the point that some built "countermeasures".
They can rather break or chip on impact... like being hammered into a tight fit. But that's just my opinion.

... J-D.

[Ivan Funk]

My understanding is that the order is:
1. Annealed to soften for working/ shaping, (how this stock I have is sold)
2. Heat treated for hardness
3. Tempered to reduce brittleness

Annealed and tempered are similar but for different purposes.

So the piece I have is only annealed. It was easy to cut to length and grind the ends nice and sand and polish etc...

It's not hardened so we'll see what happens.

[John Hyland]

In Relation to hardness it think the question is: Q: What do you want wear out last? Fingers or axle. A: fingers of course.

[Ivan Funk]

Great point John!
I had the same thought.
Much easier to replace the axle than find new fingers.
Thanks.

I'll report back in 20 years with an update.

[Mark McCornack]

Very true! And in my case, I'm sure that my fingers will wear out before my guitar's