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U-12 question (Page 1)
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| This topic is 2 pages long: 1 2 This topic was originally posted in this forum: Pedal Steel |
| Author | Topic: U-12 question |
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C Dixon Member Posts: 5912 |
posted 24 November 2000 02:12 PM
I have a question about something that is happening on my U-12. This is not the first time this problem has been spoken of on the forum. But I really need help if anyone knows the answer. Here is the problem: If, I engage the knee lever that lowers the E's and then engage the equivalent C6-6th pedal and release it, the 4th string (Eb)will be flat. This phenomenon is quite similar to the old "hysterisis" problem that we have kicked to death on this forum. Remember my Excel is keyless! I also experience this problem with other changes that are similar in action. Does ANY one have a known cure for this problem? I sure hope so. The only way I can stop it is to bump the knee lever that lowers the E's. But this is NOT awlays feasable while playing. Thanks and God bless you, carl |
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db Member Posts: 680 |
posted 24 November 2000 06:37 PM
I had this problem for a while and I spent some time looking at the way that the rod for that pull (and the 'F' lever) is positioned at the changer. It looked like it was hanging-up on the threads of the rod right at the changer. I fooled around with how the rod was "centered" as it was activated and released. It has gone away, but, I am not sure that what I found really fixed it or the weather or phase of the moon changed and made it better. [This message was edited by db on 24 November 2000 at 06:39 PM.] |
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Jim Palenscar Member Posts: 1566 |
posted 25 November 2000 08:02 AM
I checked this out on my guitar Carl and have not found the same problem- but obviously have the same changer as you. So- it is not the changer design that's the culprit. I did have a burr or two on my changer when I received it and took care of that before installing it. You might try looking at what db was talking about as I had a few problems like that when I originally set mine up. Also check the raise helper spring tension and back that off a titch. I'm confident that you'll find it. Jim |
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Bill Stafford Member Posts: 1347 |
posted 25 November 2000 02:18 PM
Carl, what other pulls do you have associated with this change? I lock my Es and have no problem with this change at all. And my EXCEL is the prototype keyless with a different keyless head than you specified for your guitar. (That is not the culprit with your problem, though). Listen to Jim. Take care and have fun. Bill Stafford |
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Michael Johnstone Member Posts: 2535 |
posted 25 November 2000 02:26 PM
I had that problem on my Sierra and traced it down to cross shaft flexion.What's happening is this: You are engaging a pedal or lever and activating a series of mechanical linkages ultimately raising or lowering one or more strings.This puts tension on the aluminum cross shaft-slightly flexing it - and if you hold it(or lock it)you're holding the cross shaft in the flexed position.And because the flex is infinately repeatable,you tune your lower to it.BUT! Then...you activate another(independantly tuned)lower on the same string-except that this time,you are starting from the flexed position of the first cross shaft.In my case,I was lowering my E string FROM and attempting to return it TO an already lowered note.When you relieve the tension from the first flexed cross shaft by lowering the string further with a DIFFERENT different pedal,linkage and cross shaft - and then release it back to the first lower,the first cross shaft never fully regains it's initial flex(and therefore string intonation)because the pressure to restore that initial flex is not coming from a knee lever-it is now coming from return springs,etc at the other end of the linkage where all the tensions,frictions,forces and leverages are slightly different.The fix? I tried reverse helper springs and other indescribable gizmos,doodads and hodaddies and then finally,I had Don make me a hard steel cross shaft for that E-Eb lever which has practically zero flex.Does it work? Mostly,but not 100% - it's now no worse than a dozen other intonation and temperment problems of a few cents here and there that will always plague ANY pedal steel.But it's fixed enough to go on with my life and get down to playing music. Lap steel anyone? -MJ- |
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C Dixon Member Posts: 5912 |
posted 25 November 2000 03:55 PM
Bill, Here are my pulls associated with the problem: 1. LKR lowers 4 and 8 a half tone 3. RKR raises 4 a half a tone and lowers 8 a whole tone. 3. LOK holds the E's lowered a half a tone. And lowers the 2nd string a whole tone. Whenever I use either LKR or the LOK lever, and at the same time, engage, then release RKR, the 4th string comes back flat. Upon close observation underneath the guitar I have noticed that the bell cranks on the LKR rod actually move further a little bit (when the E's are lowered) when RKR is engaged and then released. John Fabian of Carter Guitars was nice enough to call me and try to explain to me what is happening. He verifies what Micheal said. Apparently, the cross rod attached to LKR is flexing BEYOND its "stopped" location. John tryed to explain to me why this happens. And said all U-12's have this problem more or less. I listened to him very attentively. I do not know that I am smart enough to understand his explanation. For the life of me I cannot figure out why a cross-rod held hard against a stop can be flexed by something emanating from another change on another knee lever at the changer. It just does not seem to make sense to me. Yet I sit right here and see it happen. NO question but what it IS happening right in front of my eyes. But I cannot understand it. I can counteract it I am sure. I just wish I could understand why it is happening. God bless, carl [This message was edited by C Dixon on 25 November 2000 at 04:01 PM.] |
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Michael Johnstone Member Posts: 2535 |
posted 25 November 2000 04:51 PM
Another knee lever change is not causing it to flex.....it is causing it to unflex.Think about it. Besides,all the stops in the world cannot stop a cross shaft from flexing-it's two different things.A stop will put limits on a shaft from turning in it's bearings.But the only thing that will stop a shaft from flexing(maybe I should call it bending or bowing)is how stiff it is.Therefore,it should be as stiff as possible - which is why mine is hardened steel instead of soft aluminum.I suggest you try it.If that fellow at Excel is as accomidating as he is said to be,and has a machine shop,I see no reason why he would not make you one or several hard steel cross shafts.Once he sees how well it works,I'm sure he will start putting it on all his U-12s with this potential problem.And if he won't do it,any competent machinist could create hard steel copies of one of your existing shafts for a few bucks.After all,it's just square or hex bar stock with the ends turned round. -MJ- |
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C Dixon Member Posts: 5912 |
posted 25 November 2000 09:31 PM
Oh Michael, You just cleared it up for me. I read your earlier post but still did not understand it. But with your last post, it suddenly makes sense to me. Check me out if my thinking is correct. When I engage my LKR which lowers my E's to Eb I am able to tune the Eb's with the nylon tuners. But this tuning is WITH the LKR cross rod already "flexed" because of the pulling pressure. Now when I raise one of those lowered E's, it removes some of that pulling pressure. Now, when I release that raise there is not enough torgue (ya might say)to re flex that LKR cross rod as much as it was flexed before. Is my understanding correct now? If it is, you just made the lights come on in my brain. I was looking at it from the WRONG point of view. And I am indeed greatful to you. I shall fix that sapsucker. What a load off my mind. God bless you Michael, carl |
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Bobby Lee Sysop Posts: 14849 |
posted 26 November 2000 11:33 AM
How many cents are we talking about here, Carl? Just curious. |
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Michael Johnstone Member Posts: 2535 |
posted 26 November 2000 11:49 AM
Yeah Carl- It sounds like you got the picture.I suppose it's possible to devise a system of linkages that would do away with this problem,but it probably wouldn't look much like a steel guitar undercarrige as we now know it.By the way,some U-12 players espouse a more simple copedant to avoid just such complications - maybe something like Jeff Newman's 7+4 setup. Where if you want to raise the Eb back to E,just release the dang knee lever that lowered it in the first place. -MJ- |
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C Dixon Member Posts: 5912 |
posted 26 November 2000 11:58 AM
b0b, I would say around 8 cents. I have a solid fix for it. Mitsuo sent me a mod for something else. And it is adaptable for this. As I have studied it in depth now and with the wonderful help of John Fabian (Carter Guitars) and Michael Jonstone, I now have "rethunk" ( It may very well be that PSG's made in the distant future will have case hardened steel crossbars and bell cranks. And I am going to start with putting "STOPS" at both ends of all my crossbars. There is just no way that flexing (twisting) crossbar and possibly bellcranks has not caused problems all along. I am kind of excited about this. Because again with John's and Michaeal's help I for the first time now have found a definite "cause" for some of the problems we have talked about on this forum. And as any truly professinal person in the service industry knows, the second step in solving any problem, is to find its "root cause". The rememdy is usually quites simple once the true cause has been determined. Of course the FIRST step is to admit that there is a problem. It is this step that most often times prevents a cure. It is human nature to defend wrong and oft' times say it does not exist, IMHO. Thank you again John and Michael. This is great. God bless you, carl
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Pete Burak Member Posts: 2750 |
posted 26 November 2000 12:16 PM
Carl, Is this a new problem or an issue you've had since day one? |
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Jim Palenscar Member Posts: 1566 |
posted 26 November 2000 12:42 PM
Maybe the reason that I don't have the problem is that I used all stainless material for the cross-shafts- not because I specifically wanted to but more because 5/16" square was available in SS and not aluminum at the time when I wanted to make them at the place I was doing the work. Every once in a great while serendipity smiles on me- but rarely~~ [This message was edited by Jim Palenscar on 26 November 2000 at 12:43 PM.] |
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Ken Lang Member Posts: 2467 |
posted 26 November 2000 07:56 PM
Just as a side note, the hardness of a shaft has no relationship to how it will flex. The flexture is a function of the strength of the material. Aluminum has about 1/3 the strength of steel, therefore will flex far more. Stainless has about the same strength as steel with the added property of not rusting. Various alloys of each material will increase what is called moment of inertia..ie..resistance to bending. The process of heat treating a steel alloy will not make it more resistant to bending. It will make it more resistant to wear. If you apply force to two steel shafts, one heat treated and one not, they will both bend the same amount. The difference is, when the yield point is passed, the plain steel shaft will bend and be deformed permanently. The heat treated, hardened shaft will break. |
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Jim Smith Member Posts: 6399 |
posted 26 November 2000 08:28 PM
Carl, before you go hog wild putting stops at both ends of all your cross shafts, please try it on just one. We noticed the same problem at Dekley when we first started making universals and determined that the cause was the shaft bowing in the middle. When we added a center strip with bushings to support the center of the shaft, the "detuning" was significantly reduced. ------------------ |
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C Dixon Member Posts: 5912 |
posted 26 November 2000 10:33 PM
Pete, The problem has been there since day one. Jim, The cross rod is NOT bowing in the middle. It is in fact twisting (flexing). You can actually see the bell cranks on LKR pivoting further when RKR is engaged. Ken, With much respect, I thought that heat treating metal reduced the amount that metal would flex and/or twist. And this was backed up by what several builders have told me. As a matter of fact I was taught that before case hardened steel would flex it would break. Are we incorrect in our thinking? Thanks so much for all the responses folks. Luv ya all, carl |
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Jim Smith Member Posts: 6399 |
posted 27 November 2000 06:55 AM
Carl, given your extreme passion and knowledge on these issues, I'll defer to your knowledge. It's been over 20 years since I was involved in steel guitar manufacturing, so some of my memories have become clouded over the years.  In fact many of them have been proven to be so.  I'll be very interested to learn the cause and cure, should you find one. ------------------ |
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Bobby Bowman Member Posts: 1271 |
posted 27 November 2000 11:49 AM
Carl, I've scanned over all of these posts to a degree and unless I missed it somewhere, there are two things not mentioned that have, in my opinion, more affect than the crossrod/bellcrank issue. Not to say that the crossrod does not come into play here at least to some extent, but the two main culprits are the string itself and especially in the case of double lowers, the lower return spring. I don't know if there is anything that we can do to completely resolve this problem. We have such little control over the string and spring tolerances without spending a fortune to have these made to certain specifics. I have had some guitars with more of these problems and some with less. I've been able to help it some through tedious spring adjustments and trying different strings and gauges. Nothing so far, has been a definite cure. There is also the ever present aggrevation of friction to contend with. Good luck my friend and may God bless. BB ------------------ |
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Ken Lang Member Posts: 2467 |
posted 27 November 2000 07:51 PM
Carl: I am afraid you have been led astray by those who say heat treating keeps a shaft from bending. In case hardening, only the outer 1/32 of an inch or so is hardend, usually by adding carbon. The center of the shaft is still soft, and together they still follow the rules of deflection. In fact, a case hardened shaft is far more likely to bend than break. A thru hardened shaft is more likely to break, again, when past the yield point. Without getting into boring details, I'm afraid that a hundred years of tests..etc..by the American metal societies have proven the facts. That Jim Palenscar use stainless from the beginning and had no problems sorta proves the point. I'm sure the problems indicated are more than just replacing a shaft, but I'll leave that to those more familiar with it than I. It would be interesting to do some calcs. on the deflection of a given steel cross shaft say, alum vs steel, and maybe I'll do that, but I would guess it would bore more people than it would help. Ken |
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HowardR Member Posts: 5735 |
posted 27 November 2000 08:18 PM
It's not boring me. I find the evolution of this thread interesting and educational. By all means continue....... ------------------ |
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Jim Smith Member Posts: 6399 |
posted 27 November 2000 09:12 PM
Back to the Dekley days again...I guess the problem we saw is still happening and the solution is still in question, so here is what we did waaay back then. Once we saw the problem we tested aluminum, regular steel, and stainless steel shafts. I believe we tested hardened steel shafts too, but I honestly don't remember for sure. The tests we performed were to set up the same pulls on the same guitar with the same pedal and the same force. The only change was the cross shafts. We used a hanging scale to ensure the same force and set up a dial indicator to measure the deflection of each shaft. Stainless steel won hands down for minimum deflection (amount of bow when the pulls were applied), lack of deformation (meaning they returned to their original shape) and with no plating necessary, cost us just a little more than regular steel. Aluminum shafts were obviously the lightest but had very visible deflection and deformed very easily. Regular steel deformed very little but the deflection could still be seen with the naked eye, and would need to be plated to prevent corrosion. ------------------ |
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Ken Lang Member Posts: 2467 |
posted 27 November 2000 10:40 PM
Guess I'll go ahead with the calcs. I'll use my MSA as a target. 3/8 dia cross shaft with about 7-1/2" between frames. Simple deflection is easy, given the forces involved. Not actually knowing what those forces are, I'll use 200 lbs. String pull should be about 50 lbs max, but the pedal forces are more difficult. 200 lbs should more than cover it for straight deflection. Torsional forces are more difficult as they involve the distance from the center of the shaft to the end of the link arm pivot. One thing at a time I guess. At the very least it will provide a comparison between aluminum and steel (or stainless steel)and we can go from there. Another part of this is the bearings used at the shaft ends. I doubt there are many ball bearings used and I suspect most use a composite or nylon bushing for the shaft to run through. Clearances with a ball bearing may run to .005 thousands of an inch and nylon the same or more. I suspect those clearances may have more effect than shaft bending. The real question may be: What movement of a shaft in thousands of an inch translates to cents flat or sharp? At any rate, let's look at deflection first. |
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Don McClellan Member Posts: 882 |
posted 27 November 2000 11:54 PM
Aloha folks, One of you said that this problem is common to ALL universals. That is not true. It might be common among universals that employ that type of copedent and/or a lock but not all universals work that way. Just thought I'd clearify that. Don |
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Jim Smith Member Posts: 6399 |
posted 28 November 2000 07:10 AM
Right, we're not talking strictly universals. The problem occurs on EVERY change. However when a pull affects a string only once, it's tunable. Changing a string pitch twice exposes the problem, as in the case of lowering the 8th string E-D# on a knee lever then lowering the same string to D on a pedal. Any tuning that uses a double lower (or raise) will show the same effect. I haven't tried the 4th string E-F followed by raising to F# (that's not a combination I use) but I assume the same thing will happen, the F will be sharp after letting off the C pedal. ------------------ |
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C Dixon Member Posts: 5912 |
posted 28 November 2000 09:58 AM
Correction because I was wrong again! It would do NO good to install a stop at both end of the shaft. Reason? The flexing never allows the distant end to get to the stop!! In fact that IS the problem. However there IS an easy fix. But it will clutter the rod area under the neck. I say fix because that is purely what it is. It is NOT a cure. The cure would be to find a material for the crossrod that did NOT flex. Whether I can find one or not is debatable. But the discussions on aluminum versus steel/stainless steel is most interesting. One thing is for sure, the problem is NOT a myth. It is not the string! IT is NOT in the changer. It is NOT the cabinet. The dang crossbar is flexing (twisting) when it pulls the two E's from E to Eb. I sit right here and SEE the two bell-cranks move FURTHER when The equivalenat C6-6th pedal is engaged while holding the E's lowered. I also see them NOT return to the position they were in BEFORE additional change was made. Also, NO amount of adjusting of the "return springs" has any appreciable affect without making LKR so dang stiff it would be unnaceptable. And even here, the amount of help is only 1 or 2 cents. I need a lot more. The problem IS caused by the cross bar twisting (flexing) when it initiates the pull. Then when something else pulls one or both of those strings further, that twist is lessened. And remains there even after that other pull is removed. So from my limited knowledge, it must be concluded that a shaft that did NOT twist (or flex) would stop it cold in its tracks. Now I am going to try and find a material that will fit the above "specs" May God be with me as I do, carl |
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Michael Johnstone Member Posts: 2535 |
posted 28 November 2000 10:27 AM
It's not so much twisting as it is bending or bowing in the middle where the bellcranks are attached-that's where the tension is coming from.It may be twisting also,but that's of minimal concern compared to bowing.Another thing I've done is put seperate stops on the pedal and knee levers themselves-then I syncronize the cross shaft stops so they all bottom out at the same time.Once properly adjusted,a little drop of "Locktite" on the set screws will put that issue to rest.Which leaves the issue of bowing and like I said,the fix is steel cross shafts or some other inflexable material-carbon fiber or maybe some kind of polymer plastic? I'm always hearing about some new material that is supposed to be "harder than steel" any metalurgists out there? -MJ- |
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Bobby Bowman Member Posts: 1271 |
posted 28 November 2000 07:52 PM
Carl, If you've a mind too, you can make up a prototype from old parts you probably have laying around. Make a crossrod as short as possible (which will have less twist, flex, bend and or bow), put the changes you have in question on the prototype. You will find that the problem still exists. Maybe not quiet as bad, but nonetheless, still there. When you stretch the spring a given length and then release that tension only partially, or increase it even more and then release it partially again, the pitch of the string will not be true to what you need to be in tune. I don't know the proper term to call this effect, but I've done the experiment several times over the years and always had the same results. Whatever law of physics this is also applies to the string. It has something to do with changing the molecular structure within the metal. I'm not formally educated in this field (or even informally), but I know through years of dealing with most of the problems associated with the pedal steel, and having such respested teachers as Bud Carter, Tommy Morrell and several others, as well as probably hundreds of discussions with other builders and repairmen, that it's not just the crossrod and/or bell crank by themselves. All of these things combined together is the problem. But, I assure you, that if you have success with the crossrod problem, and I surely hope you do, that the problem will still exist to some degree. Perhaps if there was a definite consistency in the materials used we could have a lot better luck in these matters, But to this day, there is not that consistency and we are fortunate to be lucky enough from time to time to get the right combination together at the same time on the same guitar. To me, this explains why every once in a while you have a guitar that has less problems than others or vice-vercy (sp?) You know as well as I or anyone else, that you can have ten guitars of the same brand set up identical to each other and be lucky if two of them are exactly the same. Each and every guitar has its' own individual personality. And Carl, I say none of this as an argument, but only meant to share our thoughts and experiences together. Again, good luck my friend. BB ------------------ [This message was edited by Bobby Bowman on 28 November 2000 at 08:12 PM.] |
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Ken Lang Member Posts: 2467 |
posted 28 November 2000 08:32 PM
Well, I ran some numbers today. I used the formula for a beam fixed at both ends with the weight in the middle. The cross bar is not truly fixed at both ends as it runs in bushings that allow it to turn, but it's close enough to compare. ! (---------------------------) Picture the dotted line as the cross bar and ( representing a fixed point at each end. The ! in the center above the line represents weight pushing downward. I presume no one is interested in seeing the actual formula, but it's straight out of The machinist handbook. I used steel as a base; remember aluminum is 1/3 as strong. Taking a shaft 3/8 in diameter and 7-1/2" between fixed points, these are the results. With a 200lb load the shaft would bow .007 thousands of an inch. Aluminum would bow .021. At 50 lbs the shaft would bow about .002 ; aluminum about .006 or roughly twice the thickness of a human hair. My guess is the actual amount is more because the shaft is not fully fixed. For example, a shaft only supported at the ends would bow 1/16 of an inch under a 200lb load. I also ran some calcs on torsion-or twist. Guessing at a lever 1" from the center of the cross shaft and pulling 50lbs, with one end of the shaft at a stop, the other end would Twist about 1 degree. In aluminum-that would be three degrees-enough to see for sure. I guess I haven't convinced everybody that hardness has little to do with bowing but that remains the fact of the matter. The modulus of elasticity for steel is 30 million,and for aluminum 10 million. If someone used a material with a modulus of 60 million, then---the shaft would bend half as much. By the way MJ, there are materials harder than steel, cobalt being one. The good part is it wears very well and is used as cutting tools. The bad part, other than expense, is it shatters easier under load. The ultimate solution, use bigger diameter cross shafts. I hope I haven't bored everyone to death. Do I hear snoring out there? Ken |
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Michael Johnstone Member Posts: 2535 |
posted 29 November 2000 07:16 PM
Bottom line: steel shafts bend 2/3 less than aluminum and so they will fix 2/3 of the problem. I call that better than nuthin' -MJ- |
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Jim Smith Member Posts: 6399 |
posted 29 November 2000 07:48 PM
Except that no builder I know of uses aluminum cross shafts, probably for that very reason. I think we're now into finding a type of steel or synthetic that bends less than what is used now. I'm not sure if any current builders are using stainless shafts or not, but stainless bends a lot less than regular steel. |
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ToneJunkie Member Posts: 245 |
posted 29 November 2000 11:41 PM
Interesting thread. It has occurred to me on more than one occasion that it would benefit the crossrod bow problem substantially if multiple bearings could be spaced along the span of the rod (like between each string pull or every other string pull). The suggestion for a larger diameter rod also sounds promising. But if you could devise a series of narrow bearings to span the rod and support the rod between the bell cranks, then the rod would be prevented from bowing just like the crankshaft in an engine is prevented from bowing by the bearings periodically spaced between the cylinders. Narrow width bearings though, not much space between those pulls. Also anchoring and fixing the bearings such that they stayed put with respect to the shaft end bearings - kinda leads you to thinking of a milled metal under chassis... Is this a wierd instrument or what? Cheers all ------------------ |
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C Dixon Member Posts: 5912 |
posted 30 November 2000 06:39 AM
Jim, My Excel and my Sierra has (had) aluminum cross shafts. Tone, Supporting the cross shafts between each bellcrank, or even every other bell crank would in fact prevent bowing. However I see two problems here: It would not stop the shaft from twisting, which is what is happening more so than bowing in my case. Secondly, one of the serious constraints for PSG manufacturers from day one has been the limited space width for bell cranks. In most cases there is just enough room for the bell-cranks themselves and two cases I know of where there is not enough room, if the pull rods are to be kept parallel to the front apron (the desired method). These two are the P-P Emmons and the Linkon. They are both wider than the spacing between strings. (Note: I am referring to cases where bellcranks are located on adjacent strings such as the C pedal, the 5th, 7th and 8th pedals, etc). And if you just put them in the spaces where there were no bellcranks, they could very easily get in the way of possible future set-up changes. Thanks to both of you for your comments. God bless you, carl |
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Jim Smith Member Posts: 6399 |
posted 30 November 2000 07:08 AM
quote:Carl, you may have just given a partial solution to your problem. I think the shafts are both twisting and bending. If you have aluminum shafts now you will see a huge improvement just by going to steel (preferably stainless) shafts. I'm no metallurgist by any means, but I can visualise aluminum twisting and bending much more than steel. |
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Marco Schouten Member Posts: 920 |
posted 30 November 2000 07:17 AM
Very interesting thread, I wasn't bored at all. Question: does the shape of the cross shafts have any influence on bending or twisting? e.g. square, round or hex? ------------------ |
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HowardR Member Posts: 5735 |
posted 30 November 2000 09:34 AM
I agree. I find this a most interesting and informative thread.Even though I don't play pedal yet,and am lost in trying to conceptualize the exact workings of the undercarriage,I am absorbing some knowledge here. Certainly more fascinating than "what color should the leg caps be if I order a 19 string guitar" ------------------ [This message was edited by HowardR on 30 November 2000 at 09:36 AM.] [This message was edited by HowardR on 30 November 2000 at 09:39 AM.] |
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Jim Smith Member Posts: 6399 |
posted 30 November 2000 09:41 AM
I believe the theory is that round shafts bend and twist less, but I don't recall what theory that is, or where I heard it. If nothing else, round shafts are the only way to go if you want to use bearings, bushings, or braces to help prevent unwanted movement.  |
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rhcarden Member Posts: 140 |
posted 30 November 2000 10:50 AM
Carl, I think you can fix this problem by using one ------------------ [This message was edited by rhcarden on 30 November 2000 at 11:06 AM.] |
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Jim Smith Member Posts: 6399 |
posted 30 November 2000 11:14 AM
Bob, have you tried Carl's scenario from his first post and do your changes come back in tune? I don't see how or why your setup would make any difference. Carl, after all this back and forth posting, I went back and read your original post. You're complaining about your 4th string, yet I see it much more on the 8th string. Does your 8th string come back to D# in tune after lowering it to D? |
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Michael Johnstone Member Posts: 2535 |
posted 30 November 2000 12:31 PM
From all that's been discussed here and in a similar thread from around a year or so ago in which someone actually ran calcs on the surface tension of round vs square vs hex vs oct cross shafts,etc,etc.- I think the one design mod a manufacturer or aftermarket rebuilder could make which would have the best result with the least impact on other elements of their basic design is to go to somewhat larger,stainless square or hex cross shafts riding in hard bearings that are as slop free as possible.And I'm not so sure that Delrin is the last word in bearing material. -MJ- |
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Jim Smith Member Posts: 6399 |
posted 30 November 2000 12:55 PM
Michael, could you post that surface tension link if it's still around? At Dekley we used Delrin for blocks to mount the foot pedals in because it could be molded. My 20 year old Dekley has no slop or wear from the pedal shafts at all. We used nylon cross shaft bushings because they were available pre-made and thus cheaper. The reasoning was that the shafts rotate much less that the pedal shaft itself. |
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