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Posted: 29 Aug 2010 9:01 am
by Bill Dobkins
Chris's last name isn't really Hankey is it ????
Posted: 29 Aug 2010 9:05 am
by Tony Glassman
Chris Lang wrote:NOW, add that "rise" and "fall" to the bent crossrod design and you have even more "rise" and "fall"|
....so what!
Additional rise & fall just spread the work load over a slightly longer distance. That results in an infinitesimally longer and EASIER pedal throw.
If that's not to your liking, there are plenty of changer/bellcrank choices to stiffen and shorten pedal excursion.
......
just out of curiosity, have you ever even tried a G2? 
Posted: 29 Aug 2010 9:05 am
by Chris Lang
b0b:
Not true. The elliptical path created by the bent crossbar creates less rise and fall of the pull rod at the point where it attaches to the rod puller (bellcrank). It's a very real, patentable advantage, in my opinion.
Frankly, Chris, I just think that you don't like the way bent crossbars look. Either that or you're just stirring up sheep for the fun of it.
No way!
b0b you know better than this. When the crossrod is actuated, the bell cranks
will in fact rise more than a straight crossrod. Anyone can see this. Folks may not want to admit it, but that does not change the fact.
Take a coat hanger and fashion it to scale identical to the "bent" Mullen counterpart. Hold it between your two hands, rotate the hangar a little with your finger. Watch what happens at the "bent" angles.... They "rise" and "fall", with an ever so slight twist!
Not rocket science!
However, it is science.
Physical Science!
I don't know what this
is about.
I like this one better:
Tony questions:
...... just out of curiosity, have you ever even tried a G2?
Glad you asked that!
Indeed I have looked closely at a G2, (at that time we were lovingly calling them the Mullen "crankshaft" model) and backed out of buying it.
Reason?
On it's back, I could see the crossrods "lifting", as they were being actuated.
As far as sound went, it sounded like a Mullen. As far as the mechanical aspect went, I was concerned about potential problems, so I did not buy.
The guitar sounded like a Royal Precision, which was what I wanted anyway. Thought I would look at a nearly new G2 to try.
Posted: 29 Aug 2010 9:21 am
by b0b
You're wrong, Chris. The up-and-down movement of crossbar counters the up-and-down movement at the ends of the rod pullers. The effect (and the advantage) is most pronounced on the low strings of the E9th, where the center of rotation is furthest from the crossbar.
Your coat hanger doesn't have anything attached to it. You're not looking at the whole system.
Posted: 29 Aug 2010 9:31 am
by Pete Burak
Why are you guys rehashing this?... (fwiw, can we get the You-Tube of the bent cross-rods back online?).
http://bb.steelguitarforum.com/viewtopi ... sc&start=0
With all due respect I'm not familiar with Chris Langs Pedal Steel credentials.
Any links?
Posted: 29 Aug 2010 10:07 am
by Earnest Bovine
The bent cross shaft pulls the pull rods exactly the same as a straight cross shaft. So in a sense this is much ado about nothing.
The axis of rotation is the same for a bent shaft as for a straight shaft. The axis of rotation depends only on the 2 points where you mount the shaft at each end.
And the motion of the point where the rod is attached is the same, regardless of the shape of the pieces that attach it. That point moves by an amount AR where A is the angle of rotation (radians) and R is the radius (distance from point to axis). Motion is circular in a plane perpendicular to the axis.
You can make the in any crazy shape imaginable, but the motion of that point will be the same (determined by R and A). One way to see this is to imagine that the cross shaft and rod puller are one huge hunk of material, big enough to contain the straight shaft and the bent shaft. You can cut away all but a straight shaft, or you can cut away all but a bent shaft, or you can cut away nothing, or anything, and it will still pull the same way (assuming it is rigid).
The amount of linear pull on the rod is just R times the difference in cosines of the start & stop angles. (ignoring very small 2nd order differences resulting from the slight change in orientation of the rod).
The bent shaft has the advantage that it doesn't rub against the body of the guitar. But it looks like extra work to do all that bending, especially bending the short bits at the ends that fit in the bushings.
Posted: 29 Aug 2010 10:23 am
by Bent Romnes
b0b wrote:you're just stirring up sheep for the fun of it.
I agree b0b.
Check back in Chris' previous posts from back whenever and you'll discover that this is
exactly the case.
Posted: 29 Aug 2010 10:35 am
by Chris Lang
b0b says:
You're wrong, Chris. The up-and-down movement of crossbar counters the up-and-down movement at the ends of the rod pullers. The effect (and the advantage) is most pronounced on the low strings of the E9th, where the center of rotation is furthest from the crossbar.
Your coat hanger doesn't have anything attached to it. You're not looking at the whole system.
Huh???
Think about what you just said!
The up-and-down movement of crossbar counters the up-and-down movement at the ends of the rod pullers.
Holy bent crossrods Batman!
Last time I checked, the crossrods were supposed to
rotate! Not move up and down!
Your coat hanger doesn't have anything attached to it. You're not looking at the whole system.
Quite the contrary. I
am looking at the whole system, and if you would make yourself a little model of the "bent system", you would see that the closer your bellcranks are mounted to the "bend", the more they will rise and fall.
Realise that the "shaft" is rotating on
two different axis (I should not refer to the bent crossrod as a shaft, since that would indicate the rod being straight, which obviously it is not)
It is really amazingly simple to see with just 6-8 inches of coat hangar.
Posted: 29 Aug 2010 10:45 am
by Richard Damron
The Mullen bent cross-rod is mechanically deficient.
Does it work? Yes - but only after a fashion.
Consider the following: - If only one end of the crossrod is inserted into a ridgedly mounted bearing and then rotated, the other end will NOT inscribe an ELLIPTICAL arc but, rather, a CIRCLE. It will PRECESS. Now - place both ends of the rod in ridgedly mounted bearings and attempt to rotate them. Pressure will build on one side of a given bearing with equal pressure on the corresponding, but opposite, side of the other bearing. The ONLY reason that any rotation is possible is due to the tolerances between rod and bearing at the rod ends
Given close enough tolerances and significant rotation - after assembly - the rod would bind up in short order, rendering the assembly useless. And therein lies the only saving grace to the design. Rotation is limited to only a very few degrees - the design tolerances allowing for the inherent misalignment of shaft and bearing with rotation. The rod ends cease to be concentric with the axis of the bearing - assuming that they were when originally assembled.
In an ideal design, measures would be taken to ensure that the concentricity between rod end and bearing be maintained. In this case, it is not.
In the strictest of terms, it is a flawed design. But does it work - and work well? Apparently so. There's an old saying that says that one cannot argue with success. This design is a success - in spite of itself - technically speaking.
Respectfully,
Richard
Posted: 29 Aug 2010 11:09 am
by Chris Lang
Richard says:
The Mullen bent cross-rod is mechanically deficient.
Does it work? Yes - but only after a fashion.
Consider the following: - If only one end of the crossrod is inserted into a ridgedly mounted bearing and then rotated, the other end will NOT inscribe an ELLIPTICAL arc but, rather, a CIRCLE. It will PRECESS. Now - place both ends of the rod in ridgedly mounted bearings and attempt to rotate them. Pressure will build on one side of a given bearing with equal pressure on the corresponding, but opposite, side of the other bearing. The ONLY reason that any rotation is possible is due to the tolerances between rod and bearing at the rod ends
Given close enough tolerances and significant rotation - after assembly - the rod would bind up in short order, rendering the assembly useless. And therein lies the only saving grace to the design. Rotation is limited to only a very few degrees - the design tolerances allowing for the inherent misalignment of shaft and bearing with rotation. The rod ends cease to be concentric with the axis of the bearing - assuming that they were when originally assembled.
In an ideal design, measures would be taken to ensure that the concentricity between rod end and bearing be maintained. In this case, it is not.
In the strictest of terms, it is a flawed design. But does it work - and work well? Apparently so. There's an old saying that says that one cannot argue with success. This design is a success - in spite of itself - technically speaking.
Respectfully,
Richard
Finally, someone steps up and acknowledges this. Richard did so in a very respectful way.
He has a lot more patience than I do..........
I never said Mullen was a bad guitar, only that their crossrod design was not physically correct.
With builders seeking innovation and precision to improve their guitars these days, I was surprised to find a major steel guitar builder take,
what I believe was, a step back, and resort to bending a "shaft" in order to allow the use of a single changer model, not considering that the use of two different axis would go against the basic, elementary physical laws!
Posted: 29 Aug 2010 11:17 am
by chris ivey
i object to the coat hanger being presented in a detrimental fashion. after all it was one of the first 'main players' in the technology of the pedal steel. i think we should hold it in high regard.
...funny, i just realized i fixed a friend's maverick with a coat hanger the other day.
by the way, chris lang...it's not lost on me what you are addressing. the ends of the mullen 'shaft' aren't on the same plain which makes it definitely 'wrong' in some respects. however, it doesn't matter as long as it works.
Posted: 29 Aug 2010 11:18 am
by Bill Moran
I guess we play a flawed instrument, if you want to get so technical. Look at your tuner sometime. +8 ,
-6 , +2 ect. Does it work ? Yes. Lloyd Green's bar slants. Does it work ? yes. Half pedal lick? It works. Strait or bent cross shafts ? They all work.
Until it is broken don't worry about it. You will find more flaws in the player than the guitar. I have yet had anyone wanting to inspect my guitar from the bottom. They wouldn't understand what was going on under there anyway.
You know, I have a red pickup truck . If yours is not red it might be flawed !! Just my opinion .
Posted: 29 Aug 2010 11:22 am
by richard burton
I have no problem with the slight joggle in the cross-shaft, there will be enough clearance in the end bearings to allow for a few degrees of rotation.
However, I do see another possible problem that no one has touched on:
There is no way to fit a centre brace, to stop the shafts from flexing slightly during activation.
It's quite possible that the shafts are of a large enough section that they won't flex, but I've noticed that steels with a centre brace have a very positive 'stop' feel, with no sponginess of the pedals.
Posted: 29 Aug 2010 11:23 am
by Mickey Adams
I cant stop laughing now...
Posted: 29 Aug 2010 11:27 am
by Pit Lenz
Gentlemen, please! All your points have been made a gazillion times now, everybody´s right in their own way:
Yes, it´s pink elephants to some,
and it´s not a bug, it´s a feature to others...
In my country, we have a name for this game that even made it to your language:
Kindergarten!
I can´t believe I did really READ all this...
Now let´s all get back and spend some "ass-time", can we?
...and b0b, where is the "Yawn!"-emoticon when we really need it?
Posted: 29 Aug 2010 11:33 am
by Earnest Bovine
Richard Damron wrote:
In an ideal design, measures would be taken to ensure that the concentricity between rod end and bearing be maintained. In this case, it is not.
Richard, are you saying that they neglected to make the bends near the ends of the shafts? I cannot see that from the photos. Obviously the two ends should be on the same axis like this
I don't think Mullen would forget to make those bends. If they did, the shaft ends would fit wrong in the bushing or bearing or whatever it is called, like this
However, this is a separate issue from what think was being discussed here, which is whether bent rods somehow pull differently. As I showed in a previous post, any shape of shaft pulls exactly the same as any other whose pull rods is attached at the same radius from the axis. The only difference with the bent shafts is the extra work in making the 4 bends. (To be honest I'm not sure what some of these posts are trying to say. I think Bill Hankey could explain it better than some of them.)
Posted: 29 Aug 2010 11:34 am
by Chris Lang
Richard says:
I have no problem with the slight joggle in the cross-shaft, there will be enough clearance in the end bearings to allow for a few degrees of rotation.
However, I do see another possible problem that no one has touched on:
There is no way to fit a centre brace, to stop the shafts from flexing slightly during activation.
It's quite possible that the shafts are of a large enough section that they won't flex, but I've noticed that steels with a centre brace have a very positive 'stop' feel, with no sponginess of the pedals.
Indeed. That is a valid point! I thought about that earlier. That bend in the center will not allow the use of a center brace.
Mike says:
All I can say is lets all get bent, and have a G2.
Oh no thank you. As a teenager I used to drink and get "bent", and it always led to trouble.
I think I'll play it straight!
Mickey reveals:
I cant stop laughing now...
Oh no! You're not getting "bent" are you?
Posted: 29 Aug 2010 11:36 am
by chris ivey
ahhh...yesss...everything is beautifullll (everyone now!) ..in it's own wayyyy...
even ahab the arab....ray stevens...
even taliban joe...banjo terrorist..
Posted: 29 Aug 2010 11:38 am
by b0b
Whether the shaft is bent or not, the axis of rotation is a straight line between the ends. There are not "two different axis".
Posted: 29 Aug 2010 11:44 am
by Chris Lang
Ivey sings:
ahhh...yesss...everything is beautifullll (everyone now!) ..in it's own wayyyy...
even ahab the arab....ray stevens...
even taliban joe...banjo terrorist..
Yeah..........................
Warm and fuzzy physics...............
Cum-bye-ya-my-Lord..............
We're all a part of this great big world, where wrong is not really wrong. Black is not black, and white is not white, but rather gray..............
We're
all right, in our own
special way..........
NOT!!!
Those crossrods are not correct!
Now say it with me, it will liberate you!
Seriously........
b0b says:
Whether the shaft is bent or not, the axis of rotation is a straight line between the ends. There are not "two different axis".
Shazam!
Again, false.
The last time I looked at a G2, the axis point on end of the rods
were at two different heights!!!!
This would not matter, if the Mullen had swivel bearings, and the crossrods were not "bent"
Sadly, this is not the case.........
Posted: 29 Aug 2010 11:50 am
by chris ivey
..oh wow..cow-man has just shed an interesting light on the subject. i never considered that the bushing ends could be bent at angles to put the whole axis on the same plain, which would indeed solve this 'physics' concern. is this how they are designed or not? thanks earnest for the use of your high iq...
if so this could elevate mullen right back to their 'top of the innovative design technology' perch from 'corner cutting cheapskates'!
Posted: 29 Aug 2010 11:54 am
by Travis Hillis
Reading this really makes me appreciate the simplicity of the lap steel!
No offence, just a joke, gentlemen..
Posted: 29 Aug 2010 11:55 am
by Chris Lang
Ivey tries:
..oh wow..cow-man has just shed an interesting light on the subject. i never considered that the bushing ends could be bent at angles to put the whole axis on the same plain, which would indeed solve this 'physics' concern. is this how they are designed or not? thanks earnest for the use of your high iq...
if so this could elevate mullen right back to their 'top of the innovative design technology' perch from 'corner cutting cheapskates'!
No, still no good, and wouldn't be on the same plane. You still would have that nagging rise and fall at the "bent" part of the crossrod.
Friendly word of advise:
We need not resort to name calling. Those Forum rules, ya know.
Posted: 29 Aug 2010 12:10 pm
by Rick Collins
Chris Lang, you are not biologically correct __ you have a design flaw.
Your blood pump (heart) is located on one side of your symetrical body and too high up.
It must pump blood to your toes which is much farther away than your finger tips.
The earth is in an elliptical orbit around the sun instead of a true circle.
I just e-mailed God about these two "design flaws".
I just got his reply which said:
Rick, those are not "design flaws". I had every intention of creating them that way.
Now, be quiet about it.
Chris: Get a clue!
Posted: 29 Aug 2010 12:13 pm
by chris ivey
