Temperature Change and Tuning Stability on Pedaled Changes

[Jim Pitman]

I played the third gig (outdoors) that I've played all summer this Saturday. The temperature was ~ 50 degrees here in VT.
From experience I decided to arrive early to be able to dedicate a 1/2 hour to tuning. When I got home I set up the guitar in my 70 degree house and dedicated another 1/2 hour to tuning. It stimulated some thought.
I've owned four brands of all pull guitars.
They all have this in common:
1. The pedaled notes change pitch with temperature change.
2. The pitch falls if the temperature gets hotter, and the pitch raises if the temperature gets cooler.
3. Those changes requiring longer pull rods, ie A and B change the most. My right going right lever being the closest to the changer has the shortest pull rod and changes the least.
I have concluded that this affect is due to the thermal expansion of the material the pull rod is made of. The coefficient of thermal expansion describes how the size of an object changes with a change in temperature. Specifically, it measures the fractional change in size per degree change in temperature at a constant pressure. The type of thermal expansion we are concerned with is the "linear" type. Since all that material is formed into a skinny long rod, the degree of change adds up such that the amount of change will be proportional to the length of the rod as well as the temperature.
Ross Schafer has addressed this issue on the Sierra guitar by using a different rod material. I'm not sure what it is but I suspect it has a much lower coefficient of expansion than stainless steel.
I thought of another way - move the pedal stop closer to the changer. This is difficult to achieve with the typical all pull changer system due to space constraints and that's why it currently mounts to the axel and stops on the cabinet.
Correct me if I'm wrong but I believe the Kline guitar may be the only all pull type that has accomplished moving the stop close to the changer?
Another way would be to make a stop mechanism that changes in the opposite manner with temperature to cancel and is adjustable to address the pull rod length variability. (easier said than done)
Do any of you have an all pull guitar that has noticeably less pitch change than others with temperature?

[Earnest Bovine]

from 7 years ago:

My guess is that this temperature sensitivity behavior is due to growing and shrinking pull rods. The longest rods are more susceptable - our favorite 1st pedal.

Yes. A cold rod is shorter, equivalent to tightening the tuning nut. My pedals pull further in the morning when the house is colder.
It says here
http://en.wikipedia.org/wiki/Thermal_expansion
that thermal expansion of aluminum is about double that of steel. Apparently that explains why this problem is worse on some of my guitars.

[Jack Stoner]

I got zapped with the pedals/knee levers changing due to temperature on my Franklin. I attributed it to the aluminum pull rods. We were opening for a Marty Martel Opry Legends show at Silver Springs Park in Ocala Fl. We had to be there at 9am but didn't go on until Noon. As we were the first act our equipment was at the front and the steel set and got heated up by the Florida sun. They wouldn't let us touch our equipment until 5 minutes before we went on and I tuned the opens (they were all off) and when I checked the A&B pedals they were off too, along with the knees. I was able to "somewhat" get the A&B pedals and the knee that lowered the E's close but didn't have time for any others. I was able to squeak by with only using the A&B pedals and the E lower knee for the 1 hour set.

I learned my lesson. We opened several more of those Opry Legend shows at Silver Springs Park and I set the steel in a shaded location after that.

[Jim Pitman]

Yes Doug, as I get older I tend to repeat myself.

[Erv Niehaus]

This is one of the reasons that Emmons discontinued the bolt on changer.
Sitting on top of the metal neck, it was more subject to temperature changes.
I heard that Buddy Emmons would take a hair dryer and warm up his guitar when playing under cold conditions.
Erv

[Doug Palmer]

I think the temperature change on the strings is more of a problem. The Emmons compensator rubber O rings will cause returns to go sharp if very cold. The hair dryer is a good fix.

[Jon Light (deceased)]

I've been gigging (outdoors, exclusively) more, since July, than I'd hoped or expected....and sadly the cold end is in sight. The last couple of shows, chasing the physics of falling temperatures into the evening, have been......fun.

[Erv Niehaus]

I agree with the strings issue.
That's why I never tune up when I 1st sit down at the guitar.
I run through a few songs and then tune up.
I believe the friction from the bar and your hands on the strings warm them up and affect the tuning.
Erv

[Jim Pitman]

Yes, and then there's the affect of temperature change on the strings themselves. That's a tough one to design out.
In some cases it may not be the strings but the neck as Erv alluded to with the Emmons bolt on.
I can deal with changing the open string pitch with the twelve tuning keys conveniently on the top of my guitar. It's the 48 or so pedal/lever stops that are the big time consumer and, with some contortion required to find the correct nylon nut.

[Erv Niehaus]

An Emmons p/p is not dependent on the pull rods to stay in tune.
All the tuning on a p/p is done right at the changer.
And that involves direct metal to metal contact.
Erv

[Jim Pitman]

Yes Erv but I don't have a push pull.
(actually don't want one either)

[Erv Niehaus]

Jim,
Try it, you'll like it!
Mikey does.
Erv

[Jim Pitman]

Erv, I've actually got a D10 Emmons black PP sitting at the house that my friend John Braybant lent me.
I'm trying it!
...but, I'm not a D10 guy. In fact , it has helped my realize how much I'd miss my U12. Indeed the tone is great but my Infinity U12 has great tone too.

[Donny Hinson]

my2cents:

One of the main reasons for my last (new) guitar purchase was the fact that it had titanium pullrods. Titanium has a significantly lower thermal expansion rate than either steel or stainless steel, and far lower than aluminum. I happen to feel it's the ideal material for pullrods.

I do think that a half-hour is an awful lot of time to spend retuning when moving the guitar from one temperature to another. I don't spend that much time tuning after I change strings! I do agree that a player should always play the guitar for a few minutes before tuning, and that retuning due to temperature should involve only the tuning keys. The pedals and levers should not require retuning for such small relative changes.

[Jim Pitman]

Donny - great tip, Titanium.
In my case I'm talking a temperature change of 20 to 25 degrees, ie indoor vs outdoor. My U12 rods are stainless. You can definitely hear how out of tune the guitar was initially.
I touched all 50 pedal stop nylon hex nut adjustments. I may have been able to get away with only adjusting the rods that extend to the farthest left, maybe not. This is a half hour
job for me. That's ~ 30 seconds per adjustment. Yes, I probably can make that shorter.

[Marco Schouten]

my2cents:

One of the main reasons for my last (new) guitar purchase was the fact that it had titanium pullrods. Titanium has a significantly lower thermal expansion rate than either steel or stainless steel, and far lower than aluminum. I happen to feel it's the ideal material for pullrods.

I do think that a half-hour is an awful lot of time to spend retuning when moving the guitar from one temperature to another. I don't spend that much time tuning after I change strings! I do agree that a player should always play the guitar for a few minutes before tuning, and that retuning due to temperature should involve only the tuning keys. The pedals and levers should not require retuning for such small relative changes.

There was a post about titanium pull rods not long ago. I believe that the outcome was that titanium was not perfect because when the rods rub against each other a bit, the drag is much higher than with other metals. I believe that MSA doesn't use it anymore. At least, that is what I remember about it.

[Kelcey ONeil]

All pull guitars are particularly susceptible to such temperature/tuning issues, mainly due to the fact that the changes tune according to pedal/lever travel. Push pulls and certain pull release setup are virtually unaffected by temperature change on the changes, with only the open tuning affected. I’ve dragged on an old push pull out of storage, that was moved unceremoniously when we moved to a new house, brought it into my 70 degree house, tuned it open and the changes were still right on the money. The old gals can be finicky in some ways, but staying in tune is rarely one of them.

[Donny Hinson]

There was a post about titanium pull rods not long ago. I believe that the outcome was that titanium was not perfect because when the rods rub against each other a bit, the drag is much higher than with other metals. I believe that MSA doesn't use it anymore. At least, that is what I remember about it.

Well Marco, that may be true. Titanium is also harder to thread and bend than steel, stainless or otherwise. However, IMHO, a steel that's properly setup shouldn't have rods rubbing together in the first place! Rubbing means noise and wear, both of which should minimized in a pedal steel, as well as in most other things mechanical. One additional advantage of titanium is that it's about 40% lighter than steel.

I also feel that aluminum is a rather poor choice for pull rods because of it's excessive thermal expansion rate. Personally, I wouldn't own a steel that had aluminum pull rods, regardless of the sound.

[Larry Bressington]

I’ve spent years playing outdoor gigs, hot and Winter cold burrrrr, lol make sure you have enough slack in your pull rods, use a wound 6th will help settle it down, it should tune up and be ready in about 5 mins out of the case, I’ve played many brands and never had ‘brand’ tuning concerns. When tuning, drop below pitch, hit pedals, pull em back up, make sure it’s lubed good, and end play in nylons has some slack otherwise you’ll be chasing your tuning like a greyhound on a rabbit, especially in cooler weather, check that out Jim before digging deep.

Not to Buck heads with anyone but alloy vs steel pull rods Isent your problem, you’re not working with extreme temperatures to see thermal expansion rates on your rods, I loaded a sho bud one time with alloy rods to test that, there was no changes throughout the summer heat of 100f and 50f for the autumn, even in the vehicle at -20f showed no variance in pedal pulls. Personally I think she’s just tight chested and can’t breath, not enough slack in those nylons for Rod float, also check tuning keys to housing, 10mm.

[richard burton]

Get a ZB, they tune at the endplate, pull rod expansion has no effect, marvellous steels

[Erv Niehaus]

Richard,
You are correct.
They have a lot of similarity with the Emmons p/p changer.
Erv

[Marco Schouten]

There was a post about titanium pull rods not long ago. I believe that the outcome was that titanium was not perfect because when the rods rub against each other a bit, the drag is much higher than with other metals. I believe that MSA doesn't use it anymore. At least, that is what I remember about it.

Well Marco, that may be true. Titanium is also harder to thread and bend than steel, stainless or otherwise. However, IMHO, a steel that's properly setup shouldn't have rods rubbing together in the first place! Rubbing means noise and wear, both of which should minimized in a pedal steel, as well as in most other things mechanical. One additional advantage of titanium is that it's about 40% lighter than steel.

I also feel that aluminum is a rather poor choice for pull rods because of it's excessive thermal expansion rate. Personally, I wouldn't own a steel that had aluminum pull rods, regardless of the sound.

I completely agree. Alumuminium is a poor choice, it's thermal expansian coefficient is 21-24. Titanium is 8.5-9. Steel is 10.8-12.5.

[Lee Baucum]

It appears that the pull rods on my BMI are copper-coated welding rods.

[Jim Pitman]

Larry, I got slack. Been at this PSG thing for years. I'm certain I'm only experiencing rods changing length due to temperature affects.
Since purchasing a Peterson Strobostomp tuner I'm more sensitive to being out of tune also. The wider the temperature swing and the longer the rod, the faster that display rotates.

[Tommy Mc]

What materials are available that have lower thermal expansion/contraction? I'm wondering about something like carbon fiber or fiberglass rods. Is there a way the middle section of traditional metal rods could be replaced with a non-metallic material, retaining just the metallic ends for connecting to the bell cranks and changer? Not sure if it's practical, and it would make changing your setup a little less flexible, but it might address the thermal issue.