Will a thicker pedal bar cure "walking"?

[mike small]

My guitar wobbles and walks around the stage due to the pedal bar flexing
as the pedals are pressed. Will a thicker, stonger, less flexible pedar bar cure this and if so,
will it then create other problems ie the guitar flexing somewhere else? My fear is
that I will then have more cabinet drop.

SLIM

[Bent]

Mike I believe it can make a small difference. However, if your pedals and Kl's are on the hard side to operate, this might be a bigger reason for "walking".

[Dave-M]

I had a similar problem when I used nylon feet instead of rubber.

Rubber gets harder as it ages. Maybe softer feet are called for.

Possibly get larger OD feet, or ones with circular indents on the bottom (act like tire treads on your car).

I never tried it, but maybe a rubber mat under the PSG would help, or a little mat for each foot, or one for left and right pair!!!

A piece of steel or aluminum angle could reinforce the bar.

[mike small]

They are on the hard side to operate and that is why the flex is happening. It takes so much effort to engage the pulls that the pedal bar flexes thus causing the legs to flex in and out with it. Thereby creating the wobbling. I have soft rubber feet on there now. Stopping the steel from moving on the floor with a mat does not solve the flexing of the legs which is why the guitar wobbles when A and B are pushed.

Maybe I was not clear. Due to the pressure downwards pushing the pedals, the pedal bar is flexing so much that the legs are being pulled inwards and then pushed outwards as the pedals are released. When I reduce the pressure needed on the pedals by changing the bellcrank attachment points then the pedal rack does not flex as much and the guitar does not wobble as much. Since that option is does not balance the pulls like I like them, I want to reduce the flexing occuring on the rack and legs. A rubber mat would prevent the legs from sliping on the floor but would not prevent the flexing and subsequent wobbling of the guitar while playing.

So the question again would be whether or not a stronger, less flexible pedal rack would transfer the force that would have gone into the rack and legs and just create more cabinet drop? I mean that force has to go somewhere right?

[Bent]

Again, yes, it would help some. The pedal bar flexes because your pedals are too hard to operate. Making a sturdier pedal bar would cure the problem to a degree, but you are still stuck with hard pedals. Is there any way you could fix this by, say, installing raise help springs and softer return springs? Before you do that, make sure that all moving parts are free from dirt, old hardened lube and then lubed with a lightweight oil.
What make of guitar and how old is it?

BTW...measure the wall thickness on your pedal bar

[mike small]

The guitar is a "one off" all pull guitar so the brand is not relevant. I have adjusted everything to the lightest force I can get away with and still have the pulls balanced. The pulls are all about the same as with any other all pull guitar I have. The force required can only really be changed by a re-design of the changer finger pivot points as all other remedies have been applied. So I'm stuck with the force required, just trying to eliminate the wobble and flexing.

That being said, the pedals are not hard to push because the pedal rod bell cranks have been lengthened thereby giving me better leverage on the push. Without that leverage though it is too hard to push the pedals.

In my mind, if one part of the equation stops flexing,the next weakest point in the equation would then start to flex unless you get you get to the bottom of the pedal push first. Right now both the cab and the rack are flexing. Let's just say 1 degree. If I stop the 1 degree on the rack, won't the cab now have more force and possibly flex up to 2 degrees?

The pedal bar is stock is 1/8" thick.

[Bent]

Maybe the one-off is flexing too much over all. I have no way of knowing. Like I said at the outset, a flexy bar might be part of the problem. You say the cab flexes as well. That compounds the problem. So now we are at not only the bar any more.
Typical pedal bars are 3/16". Have one machined to 3/16" walls.
Still you have the flexing body problem.
What are your leg tips made of? Are they slip resistant? Are they intact so the leg doesn't stick thru and slide on the floor?
Are your leg threaded inserts solid without wobble? What does the guitar weigh in working mode?

[richard37066]

Mike -

My friend, Bent, will probably agree with a quick fix to your problem.

Since it's a one-off and you're willing to experiment would it be out of line to pop-rivet a 1/8" piece of aluminum to the front of the pedal bar? Might look a tad ugly, at first, but you could gussy it up to the point where it would be half-way presentable. Ten or twelve 1/4" pop rivets, evenly spaced, should stiffen it considerably. A quick fix as opposed to changing out the entire bar.

Short of changing out the changer or making major alterations to it, the most certain way to ensure minimum pressure on the pedals or levers is to approach a "linear" condition to the pulls. That is, all bellcranks, levers, etc., should move through the top of the arc when in motion. For example, if a bellcrank has to move through, say, 10° of rotation, then its' starting point will be at 5° below top dead center and end at 5° above dead center. Any other configuration only increases the force required to activate the change. Such "misalignments" are cumulative from the pedal to the changer. They add up. Once you've gotten to the point where "it's as good as it gets" as regards the most "linear" of throws, then you'll have to look in another direction should you still deem the effort to be unacceptable.

Take ALL of Bent's suggestions to heart. He ain't no fool.

Richard

[Bent]

hehe Richard, sometimes though I feel like the Biggest fool of all, to quote the Connie Francis song...
Thanks for backing up my suggestions. Yes, a 1/8" plate in the channel stiffens up the structure considerably

About your bellcranks/ rotation...I am likely silly to question you logic, which is based on science at all times but...Let's take the 10 deg rotation.How about this: Would it not be any good to start at -10 and end at 0 as opposed to starting at -5 and ending up at +5 deg?
Your way...Things start, move and end up always in an arc. My way... starts in an arc but ends up linear (it gets progressively better and better)
whereas your way gets better to a point and then worsens, ending up as bad as when it started.
What are your feelings on the fact that the movement really is minuscule and doesn't matter a whole heck of a lot anyway?

[richard37066]

Bent -

Your last statement has much merit but ONLY if things are as "linear" as one can get them.

By way of example, let's assume that a bellcrank is "leaning" to the left at a 45° angle and the pullrod is to be moved to the right. At the initiation of the pull, there are two force components at work: - A horizontal component to the right and, also, a VERTICAL component which tends to pull the bellcrank down into the crossrod. This vertical component is a function of the angle of the bellcrank. The larger the angle, the more force required to satisfy the need for that vertical component - or "moment" as the eggheads would say. As the angle approaches zero, (my "top dead center" description) this vertical component disappears and becomes zero at 0°, leaving only the horizontal (rotational) moment to overcome. If the bellcrank is displaced to the right, then the same two moments are encountered EXCEPT that the vertical moment is a PULLING function away from the crossrod. Needless to say, should the bellcrank be at a rediculous 90° then things come to a fast, screeching, halt.

In answer to your question, one might have to mathematically integrate the aggregate force required to move the crank through that 10° and do the same for my preference. I haven't done that. Intuition tells me that my scheme requires less effort.

"Think" the break angle of a string across a bridge. The greater the break angle, the greater the force down upon the bridge. It's a rough analogy but you see the similarity 'twixt the two.

In attempting to achieve a semblance of "linearity", (though it's definitely NOT linear), it follows that the closer one can get to rotation along the tangent of the arc - about the 0° mark - the lesser the force required to move the crank. It is under this condition where the vertical moment becomes truly "miniscule" and is of no consequence. Having said that, I must reiterate that - in the simplest of circumstances - there are four "moments" to be considered in the train from the pedal to the changer. The first is at the pedal itself, the second at the lever (or arm) attached to the crossroad, the third at the bellcrank and the fourth at the changer finger. If everything is close to being "linear" then the sum of the moments is at the minimum to, say, raise the pitch of the string. If, however, things are really cockamamie then the sum of the moments can be considerable. Let me qualify the term "considerable" - it will most likely manifest itself solely in an increase of the required force necessary to activate the change. For some, an increase in, say, pedal pressure is a desired personal preference. For myself, I prefer things to have the resistance of greased owl-crap. If I could use brain waves to activate a pedal, then I'd be happy. For others, not so.

Needless to say, the required force can be altered (reduced) by changing the position of the pullrod at the bellcrank and/or the changer finger but, inevitably, at the expense of greater pedal travel. We do this all of the time when attempting to have things start and end at the same time.

Can anyone say "compromise"?

I have no doubt that you, Bent, make every effort to optimize everything on your instruments and is evidenced in the final product. Why not, then, optimize the pulls - the minimum moments - when setting up the instrument? If it's "as good as it gets" then no one has a quarrel.

Richard