Pedal...force and throw

ed packard · Post by **ed packard** » 17 Nov 2005 11:02 am

If you could have your choice of the extremes = pitch change proportional to applied force only, or pitch change proportional to pedal throw at very minimal force, which would you choose?

How much force, and what distance throw?

How easy is too easy, and how hard is too hard?

Pete Burak · Post by **Pete Burak** » 17 Nov 2005 11:18 am

In a perfect world, I'd take short (very little pedal travel) and fast (very little pressure requiered to push pedal(s) all the way down).
This is one place that I noticed (at steel shows) that the Carter S12U was good at.

richard burton · Post by **richard burton** » 17 Nov 2005 12:03 pm

My world must be perfect, then.

Jerry Roller · Post by **Jerry Roller** » 17 Nov 2005 12:19 pm

Medium travel, medium pressure with a very solid stop after 1/16th inch pedal travel past the cross rod stop.
Jerry

Charlie McDonald · Post by **Charlie McDonald** » 18 Nov 2005 4:46 am

I think your perfect world comes from much experimentation and development, Richard.

I wish the force applied could be progressive--or perhaps I should say finger travel should be progressive, with the last half of pedal arc moving the finger more than the first half, giving the effect of progressive force.

What are you developing now, Ed? ;
(I don't think this guy asks merely hypotetical questions.)

richard burton · Post by **richard burton** » 18 Nov 2005 6:16 am

Charlie,
Your idea could be achieved, after a fashion, by using round cross-rods.
The bell crank could be mounted so that it was well over top-dead-centre.
Then, when the pedal or lever was activated, the amount of linear travel (of the rod going to the changer finger) would decrease as the bell crank became more and more horizontal, even though pedal/lever travel would remain uniform.
R B

ed packard · Post by **ed packard** » 18 Nov 2005 6:32 am

rb...right you are... on the older Sierras (and probably others) with round cross shafts, that trick was used to changes "timing".

Charlie...is it a particular force applied curve that you want, or is the desired result a pitch change curve?

It is probably dangerous to give piclers another adjustment = control of the force/throw curve, but good for the repair people. There are some things that can be done re that issue (if it is one).

Charlie McDonald · Post by **Charlie McDonald** » 19 Nov 2005 4:17 am

VERY interesting, Richard. I might have known you'd run into the idea.
But it's a force curve I'd be after. Thus, I would position the cranks so that they pointed to the changer, so that they have some lift before that turns into pull, increasing the mechanical advantage as the pedal travels.
But it was a thought experiment, and now I'm not sure if the actual effect would be desirable.
But watch it, you guys are making me want that old Sierra SE, round shafts and all.

ed packard · Post by **ed packard** » 19 Nov 2005 7:06 am

Charlie...think CAMs to get the curve you want. I don't know of any instruments using cams, but it is there to be done. The changes activation is already complex considering all the connecting points, stops, springs, et al, so what is 10 or 20 cams added?

The halftone stretch (strain) on a 0.011" string tuned G# on a 25" keyless neck is something like 0.040", and the tension on the string is something like 30 pounds. The throw at the tip of the pedal might be about 0.875 inches, and the force on the pedal (at the tip) might be about 1.5 pounds for that single string.

With the alternative holes, slots, pedal lengths, etc. along the path, the pedal throw might be adjusted to range from 3/8" to 1.5", and the pedal force required for that one string from 3/4 to 2.5 pounds...round numbers; more strings per pull = more pedal force required.

There seem to be two types of players (the extremes)...one wants to speed pick and chromaticize the notes in the changes (wants short and quick), the other wants to gliss between the notes in a very controlled manner (wants longer throws and quite noticable force).

Should all pedals exibit the same throw and force or not?

Tom Campbell · Post by **Tom Campbell** » 19 Nov 2005 8:05 am

The Sierra Session, which has square shafts, has an adjustment for changing the pitch(arc)of the bell cranks. Very nice feature.

Charlie McDonald · Post by **Charlie McDonald** » 19 Nov 2005 9:21 am

An interesting idea, Ed; at first I was thinking of a sophisticated device until I read Richard's simple solution. A cam is a wonderful thing--one where the pedal lever would contact it on the end of the cross shaft, giving a progressive pull? It wouldn't be too complex, and would make for a smooth interaction.
I fit in the glissando category; I'll bet a poll would show that most players aspire to be 'speed pickers.'

You know, the more I think about it, the more a Session seems like the right choice.
The seven levers on an SE might be ridiculous; and pedals can be added, right?

ed packard · Post by **ed packard** » 19 Nov 2005 9:29 am

Pedals and levers can be added.

The round shaft allows setting the arc of each bell crank, and to extremes...I fooled with that back when on the SIERRA pre SE models...nice for those that needed it, I did not.

The SESSION square shaft bell crank arc adjustment is limited in arc, and ALL belcranks on a shaft would have the same amount of arc (unless I am missing something...Tom?

Lee Baucum · Post by **Lee Baucum** » 19 Nov 2005 10:36 am

ed - How about designing some adjustable bell cranks, whereby the angle of the crank could be adjusted? Of course, they would have to be extremely stable. Perhaps with interlocking teeth, like on some adjustable amp stands.

Lee

Michael Barone · Post by **Michael Barone** » 19 Nov 2005 10:37 am

Charlie & Ed, your ideas reminded me of an earlier topic, where there is a pretty good discussion about modifying pulls on rounded cross shafts: http://steelguitarforum.com/Forum5/HTML/010799.html

Mike