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Topic: pedal and knee lever ratio |
Dwight Lewis
From:
Huntsville, Alabama
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Posted 4 Oct 2008 3:00 am |
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| I dont know how to word this but I can say this that I like to have my pedals and knees leverage ratio as short as possible to change my string note. with a double raise double lower changer and 3 position bell cranks( MSA Classic) how would I set this up? |
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 4 Oct 2008 4:37 am
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You realize, of course, that making the pedals and levers have a shorter throw makes them "stiffer", or harder to actuate?
That said, you'll want to change the pull rods to the holes that are farthest from the crossrods, and then you'll probably also have to reduce the pedal travel, which is done by adjusting the pedal-stop allen screws which are in the strip along the front apron.
Balancing out the pulls and getting the changes in tune with a minimum of slop could take quite some time. |
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Richard Damron
From:
Gallatin, Tennessee, USA (deceased)
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Posted 4 Oct 2008 11:48 am
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Dwight -
Donny's post is on the money but I might inject one or two things to consider. When you get things too "tight" and instantaneous then finding a "1/2 A pedal" (E9) or "squeezing" a raise or lower can become problematic. In addition, accidentally leaning on a pedal or lever may cause things to seem slightly out of tune. A compromise just might be in order as I found out - the hard way. If you play with it long enough then you'll find that which suits you. Donny also aludes to the notion that you shouldn't be afraid to experiment - Just take your time in doing so.
Respectfully,
Richard |
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Dwight Lewis
From:
Huntsville, Alabama
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Posted 4 Oct 2008 11:55 am pulls ratio
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Richard you are right and I am considering this compromise. Thanks you guys.
Dwight |
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Ulf Edlund
From:
Umeå, Sweden
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Posted 4 Oct 2008 12:56 pm
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I've never understood this "as short travel as possible" thing.
I have been through hours of field testing and i found that i defenitively prefer a smooth pedal with a slightly longer throw before a stiff one.
One of my delusions (spelling?) was that shorter throw would play faster, but it didn't, not for me anyway.
Remember to write down a rodding chart before you change anything. It will save you a lot of time if you want to go back.
Ulf
_________________
1983 Emmons D10 SKH, Carter SD10, Nashville 112, Session 500, ProfexII, Lapsteels, GT-Beard reso, guitars of all kinds...
http://www.myspace.com/ulfedlund |
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Tony Glassman
From:
The Great Northwest
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Posted 4 Oct 2008 2:20 pm
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| Ulf Edlund wrote: |
I've never understood this "as short travel as possible" thing.
One of my delusions (spelling?) was that shorter throw would play faster, but it didn't, not for me anyway.
Ulf |
Shortening the throw at the cross-shaft is done by moving the pullrod further away from the cross-shaft at it's connection to the bell crank.
This in effect moves the fulcrum (cross shaft bracket) proportionally closer to the effort (knee lever) and further from the load (pullrod). You lose leverage, which means a shorter (faster) throw requiring more force to accomplish......It's basic teeter-totter physics. |
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Ulf Edlund
From:
Umeå, Sweden
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Posted 4 Oct 2008 3:33 pm
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Oh.. I'm well aware of HOW you do it.
I don't understand WHY. 
_________________
1983 Emmons D10 SKH, Carter SD10, Nashville 112, Session 500, ProfexII, Lapsteels, GT-Beard reso, guitars of all kinds...
http://www.myspace.com/ulfedlund |
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Roger Shackelton
From:
MINNESOTA (deceased)
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Posted 4 Oct 2008 3:53 pm SHORT & EASY PULL?
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This is very possible on a BLANTON PSG, due to the unique All Pull System.
Again the shortness of a pull is not in your best interest when doing a 1/2 pedal pull. 
Roger |
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Doug Seymour
From:
Jamestown NY USA (deceased)
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Posted 4 Oct 2008 7:01 pm
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| I thought the old MSAs were 4 hole bell cranks not 3?? |
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Ulf Edlund
From:
Umeå, Sweden
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Posted 5 Oct 2008 8:24 am
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Mine had a few 3 hole bellcranks among a majority of 4-holers.
_________________
1983 Emmons D10 SKH, Carter SD10, Nashville 112, Session 500, ProfexII, Lapsteels, GT-Beard reso, guitars of all kinds...
http://www.myspace.com/ulfedlund |
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C Dixon
From:
Duluth, GA USA
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Posted 6 Oct 2008 5:55 pm
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Moving the pull rod further from the crossbar indeed shortens the "throw" and "stiffens" the pull. We learn this in "leverage 101" if we listened in school!
However, just the opposite is the case at the changer. Here the closer to the changer the shorter the throw and the stiffer the pull.
This has tripped up more than one over the years. But there is MORE.
You may not be able to do it in every situation. In addition, "timing" of pulls can be critical if one wants a very smooth acting pedal or knee lever. But this may not be possible in all situations either, due to specific "holes" already being used. etc.
It is this quagmire that is often a builder's nightmare, especially on more complex copedents, not to mention what can happen when someone gets under there "messin" around.
So be careful. There are just so many possibilities and just about as many problem possibilities as well. As one poster said, "write down" what you have. And do it BEFORE you get into trouble. Then you can always get back to where it was before ya "messed" with it.
And may Jesus guide you in your quests,
c.
_________________
A broken heart + † = a new heart. |
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