Another string to pitch issue

[Wayne Brown]

OK here we go again. I have a string that won't return to pitch after using the knee lever, however it is a little different in nature. I will explain all what I have done to correct the problem so we don't get posts explaining something I have already done. I am hoping you folks may come up with something I may have missed, as I am just shaking my head...LOL. The guitar I just built (see out west steel in builders corner) ...has a MSA style changer.
The problem I am having is this...It is 4th string on the LNR lower 4 and 8...after I use the knee lever the string returns about 5 to 8 cents sharp. When I use the LNL to raise 4 and eight come back in pitch. When I use LNL and pedal A. Same back to pitch. When i use C pedal and LNR it comes back 5 to 8 cents sharp. The problem is so small you can't really see anything going wrong.
If after using the lower or combination with the lower and it returns sharp, if I activate the LNL it will return to pitch. here's what I have done to correct the problem.
1 checked roller for burs and oiled it
2 pulled changer out and physically checked the changer. It seams to be operating normally.
3 pulled changer again and switched fingers and scissors around
4 checked and changed spacer washers on the fingers/scissors
5 pulled all the rods on that finger to isolate the changer, string, and roller...still does the same thing as stated above.
6 checked cross shafts, bell cranks, bushings for binding
7 check for rod center in the changer end so the collars don't bind
8 checked and exchanged lower hold spring in case it was week
9 there is free space before the rod engages the scissor so rod travel is not in the equation as well
As i keep thinking about this issue. If it was binding...physics dictates that if the string was coming from a raise down to normal it would be sharp...and coming from a lower to normal pitch it would be flat...

I know I have missed something...if you have any ideas please feel free to let me know.
I have taken some pictures to help associate with the issue.




thanks
wayne

[Ian Worley]

Is this a new problem on a guitar you've had for a while, or a new guitar? You didn't mention anything about the age of the strings. Plain strings tend to harden as they age, particularly along the end section where they remain in contact with the changer finger radius, they become less flexible. It's a common cause of this sort of issue.

[Wayne Brown]

Thanks Ian however the guitar can be seen in the builders corner (outwest rare wood steel) and has had 3 new sets of strings put on it in the last 5 days just to negate that problem. Also i have miked the Changer fingers themselves with another MSA and are all within specs. I thank you for your response though.
thanks
wayne

[Ricky Davis]

3 new sets of strings

What Brand??
I have encountered a tremendous inconsistency in certain brands wire "SAME GUAGE"; with their flexibility EVERY PULL.
I get to check out almost every brand; as I've been restoring ShoBud's for over 28 years, and the client always sends the strings he uses along with the steel. I always check out their brand(as I've already been around every block with every string maker; is also why I ONLY USE, and Endorsed by Jagwire, and customize my Artist Series with String gauges designed for he 24" scale ShoBud(what I work on and play). Also found the Consistency with only one other brand and that is D'Addario NYXL string. Also finding that a .015p in the high E position is even MORE consistent in going and coming back both ways from these two makers of their own String.
Good luck....> oh and it really seems you have looked and checked out every path in your quest....but the balance of Spring tension on "lower return spring and raise spring" can help a ton. Also; just try unhooking the raise spring and see if tuning of raising and lowering balance out more.
Ok good luck...
Ricky

[Wayne Brown]

Thanks Ricky. The strings are GHS GB-e9 as for the springs there are only the ones on the bottom of the changer that connect to the lowering part of the fingers. The raise tention is by the string it's self. I have some spare GHS 15s here i will try that in the morning.
thanks
wayne

[Bill Moore]

Try adding more travel to the lever. Or maybe move the rod to a hole at the changer that gives more travel. It looks like that is the only thing you haven't tried, and will probably correct the problem.

[Wayne Brown]

Thanks for the reply Bill however as stated in the original post there is space between the scissor and the tuning nut so travel cannot be the problem . Also it only happens when returning from lowering 4 and 8
thanks
wayne

[Ian Worley]

I found your other thread about the guitar Wayne, nice work! Based on the troubleshooting steps you described in your OP it sounds like you're certain that the fingers are returning firmly and consistently to their stops. If so, the source of the problem is almost certainly on the top of the guitar, something affecting the way the string itself is returning from a lower, somewhere between the tuning keys, roller nut and changer.

...As i keep thinking about this issue. If it was binding...physics dictates that if the string was coming from a raise down to normal it would be
sharp...and coming from a lower to normal pitch it would be flat...

In most cases the opposite is true, particularly if the roller nut is what is causing the issue. On a lower, the string tension present behind the nut pulls a tiny bit more of the string's length over the roller between the nut and tuning key. If, when the lower is released, that tension doesn't re-balance due to some added resistance in the roller or something, the changer is essentially pulling a slightly shorter string back to neutral, so the string will be slightly sharp until you engage a raise to pull the tension back into balance on either side of the nut. This is a fairly common issue. The elongated MSA key head with more string length north of the roller nut would tend to exacerbate this sort of problem.

Can we assume that the 4th string pulls very straight over the roller nut? If it was pulling slightly to one side, the outer face of the roller can bind slightly against the slot in the key head, or even on the axle, even if in spins freely and smoothly with no string.

[Wayne Brown]

thanks Ian that is food for thought. Tomorrow morning i will change out that roller nut to check that possible problem
thanks
wayne

[Bobby D. Jones]

Went to Builders Corner and looked through your pictures of the build, Great looking steel.

I played and gigged a MSA S10 Classic from about Jan. 1999 to 2017, When I went to a S12 Universal tuning. I had trouble with a string not returning too, When I got the guitar. When a 10 string guitar is built with a 12 string Key Head, It can cause problems, By the extra dead string in the key head.

When I had the problem with a string not returning, I traced the problem to the nut roller. The shaft that the roller turns on, I found some rust on the shaft. Polished shaft with 0000 steel wool.

Checked the slots and polished the sides of all the slots with Crocus cloth folded around a metal ruler.

I removed each roller, Polished both sides of the rollers flat on Crocus cloth laying flat on bench, Returned to same slot.

I lubed the rollers with Zebo Silicone Fishing Reel Grease. Best lube I found for under pressure parts.

When you put the strings on the tuner cap span maintain as straight a pull on the string to the key head across the nut roller as possible. Some strings may have to be rolled to the outside to maintain straightness.

Every 3rd string change, I would remove the shaft, and polish with 0000 steel wool, Clean the rollers and relube them. Strung the rollers on a string I had removed from the guitar to keep them in order.

This was my solution for the problem.
Good Luck and Happy Steelin

[Donny Hinson]

Wayne, the problem you describe is usually caused by the nut roller not being free enough. Bobby gives good advice, in that the string must pull in a straight line between the nut and the tuning key. Any sideways tension means that friction can be caused between the roller and the support ears on either side of the roller. I've also seen this problem caused by the string being wound backwards (on the bottom of the tuning key), which causes too much downward tension on the roller. Like Bobby says, the roller shaft should be clean and polished, and there should be either oil or light grease used on the rollers.

The only other problem I see in your pictures is that the 4th string is not centered on the top of the finger, but this seldom causes problems.

[Wayne Brown]

Well Donny and Bobby i took off the 4th string and there was some left over polishing compound in the rollers, that has now been corrected. However that was not the problem. It is still doing the same thing. I have now confirmed that the string is pulling straight on the roller. When i get home this morning i will try Ricky's suggestion and change out the string for a 15. I will check it out and inform you folks what i found.
Thanks
Wayne

[Bob Carlucci]

I have solved similar problems in the past by simply trying a smaller diameter pull rod from the bellcrank to the changer.. That rod can look and fit fine when placing it through the changer and into the bellcrank, but when activated by a pedal or lever, can deflect or bind ever so slightly and cause all kinds of headaches you will never find because everything "looks good"... I have repaired issues by either smoothing out the changer holes with a tiny round jewelers file, or simply putting smaller diameter pull rods in from the changer to the bellcrank. Seen this probably 3 or 4 times in the past few decades .

[Wayne Brown]

Folks you don't know how much i appreciate your input...I really do. However is what has me stumped is that it is not displaying normal physics. If there is a bind then it would come back flat...It is not ...it is coming back sharp. Then if i activate the raise on the same string it will come back into normal pitch and everything works properly.
thanks
wayne

[Donny Hinson]

However is what has me stumped is that it is not displaying normal physics. If there is a bind then it would come back flat...It is not ...it is coming back sharp. Then if i activate the raise on the same string it will come back into normal pitch and everything works properly.

It's not contrary to physics, not if the problem is at the nut! I will try to explain what normally takes place:

When you lower the string, there is equal tension in front of and behind the nut. Then, when you release the lower (and the nut roller isn't free enough) the tension on that part of the string behind the nut doesn't change. Since that part of the string behind the nut didn't "equalize", the effective string length (not scale length) is shorter, and the string comes back sharp. Then, when you activate the raise, the additional tension overcomes (breaks loose) the nut roller friction, and the string tension equalizes, which lowers the whole string to the proper tension when you release the raise.

The only other problem I can think of which might cause the issue you describe is that the finger stop plate has an irregular edge surface, and the fingers are not returning to exactly the same place after
the pedals/levers are activated.

[Wayne Brown]

Well Donny i think you hit the nail on the head. You came to the same conclusion as i did. I tried changing the size of string as Ricky advised to equalize the string tension a little more, checked every possible part that they were functionally properly. except one. When you build a steel using other parts DO NOT MISS A STEP. It WILL come back to bite you in the backside guaranteed. Here's what i missed.

Done
I will straight edge this and put it back together...CRAP. I wish to thanks everyone that offered up suggestions to try to help out a fellow forum member.
and with that said mod you can close this up.
thanks
wayne

[Ricky Davis]

Oh good on you Donny, that's usually one of the first things I check out when I'm having these problems is where are the fingers starting and resting and where they stop. and actually I check every moving part where it starts and stops, very important of the security of those places.
Ricky