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Topic: MSA Classic -- Timing Pulls |
Al Evans
From:
Austin, Texas, USA
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Posted 29 Apr 2019 7:40 am |
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On my 1976 MSA D10 Classic, I am having a hard time getting the RKR lever to work like I want it to.
Just for reference, this guitar has round cross shafts, and the only positive stop for the RKR is an allen capscrew with a sleeve, going into the aluminum side panel in such a way that it blocks the lever that rotates the cross shaft.
I have four pulls on this cross shaft, for strings 2 and 9 on the E9th neck (lowering 2 to D and C#, 9 to C#, with a feel stop when 2 hits D) and for strings 4 and 8 on the C6th neck (raising both As to A#).
I've got it adjusted so all notes hit their targets, but 1) the feel stop is not working, and 2) the raise for the 4th string on the C6 neck is way out at the end of knee lever travel, and the note is in tune only if I jam the lever up hard against the stop.
I feel like I'm missing something fundamental in my efforts to adjust these pulls. Maybe something to do with the positions of the bell cranks on the cross shaft?
I would greatly appreciate it if somebody could give me an outline of how to approach getting all these pulls to work easily and right!
--Al Evans
_________________
2018 MSA Legend, 2018 ZumSteel Encore, 2015 Mullen G2, G&L S-500, G&L ASAT, G&L LB-100, Godin A4 Fretless, Kinscherff High Noon |
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Tommy Mc
From:
Middlesex VT
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Posted 30 Apr 2019 9:27 am
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My initial thought about the feel stop is that with 4 pulls connected to the lever, the point the D engages is getting lost behind the pulls on the C6 neck. Common wisdom is to stiffen the return spring on the D string (by shortening it) but with 2 other pulls engaging at different times, that may not work. Some people put the two changes on different levers rather than mess with a feel-stop.
As far as the timing goes, you may need to play around with which holes in the bellcrank each pull is connected to. If you aren't getting enough travel from the 4th string on the C6 neck, try moving that pull one hole farther out from the cross shaft. The different holes act like gearing. Close to the shaft isn't much travel, farther out gives more travel to the same amount of lever distance. |
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Michael Hill
From:
Arizona, USA
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Posted 30 Apr 2019 7:45 pm
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I have a tiny, tiny bit of experience so here's my 2 cents.
When you have multiple pulls that need to be synchronized, you have to do a dance of adjusting where the pull rod meets the bell crank and which hole in the changer the pull rod goes through.
The adjustment on the bell crank determines how much rod movement you're going to get. The adjustment at the changer determines how much of the pull rod's movement gets applied to the changer. There's not so many options that you couldn't just fool around with these adjustments and stumble upon something that works.
Mickey Adams sells a DVD download where he goes through setting up a half stop feel. |
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Tony Prior
From:
Charlotte NC
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Posted 1 May 2019 1:10 am
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it may be a situation where "close" is all you may get.
Bellcrank positions, string gauges etc..I don't recall how many positions are on the bell cranks , I think 5 were on my old MSA.
Newer designed instruments may have more bell crank positions , such as 14, which is a benefit for getting timings more precise.
That physics stuff keeps coming back to haunt us.
_________________
Emmons L-II , Fender Telecasters, B-Benders , Eastman Mandolin ,
Pro Tools 12 on WIN 7 !
jobless- but not homeless- now retired 9 years
CURRENT MUSIC TRACKS AT > https://tprior2241.wixsite.com/website |
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Charlie McDonald
From:
out of the blue
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Posted 1 May 2019 2:25 am
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| Al Evans wrote: |
| Maybe something to do with the positions of the bell cranks on the cross shaft? |
The beauty of round shafts on an MSA is that you can rotate the crank, making it possible to fine-tune the pull.
_________________
Those that say don't know; those that know don't say.--Buddy Emmons |
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Al Evans
From:
Austin, Texas, USA
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Posted 1 May 2019 5:21 am
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| Charlie McDonald wrote: |
The beauty of round shafts on an MSA is that you can rotate the crank, making it possible to fine-tune the pull. |
This is the part I don't get. Can someone explain the physics of it to me? How is it different from adjusting the free play by lengthening/shortening the rod at the bell crank or the tuning nut?
The bell cranks are either two- or four-hole (I've got both). The changer fingers are two-up/two down except for one that has a piece Jim Palenscar made that steals one of the "lower" holes for a raise.
Thank you all for your help!
--Al Evans
_________________
2018 MSA Legend, 2018 ZumSteel Encore, 2015 Mullen G2, G&L S-500, G&L ASAT, G&L LB-100, Godin A4 Fretless, Kinscherff High Noon |
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Tony Prior
From:
Charlotte NC
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Posted 1 May 2019 5:34 am
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physics: thick strings require a different pull distance to pitch than a thin string.
I'm sure there is some elaborate formula regarding this somewhere.
_________________
Emmons L-II , Fender Telecasters, B-Benders , Eastman Mandolin ,
Pro Tools 12 on WIN 7 !
jobless- but not homeless- now retired 9 years
CURRENT MUSIC TRACKS AT > https://tprior2241.wixsite.com/website |
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Ross Shafer
From:
Petaluma, California
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Posted 1 May 2019 6:06 am
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| Al Evans wrote: |
This is the part I don't get. Can someone explain the physics of it to me? How is it different from adjusting the free play by lengthening/shortening the rod at the bell crank or the tuning nut?
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Think of the bell crank straight as top dead center (TDC).....if the bell crank starts its pull before that (crank angled towards the changer) the pull will have a rising rate, meaning the amount of lateral pull increases as the rod attachment point approaches TDC. If the pull starts at TDC or after the pull distance will shorten as the rod attachment point gets further from TDC.
The amount of pull changes throughout the arc that is made by the bell crank. Keep in mind as rising rate will increase the pedal force as it goes though its motion and a falling rate the opposite. We're talking pretty subtle stuff here, but its happening and can be used for fine tuning, though its is not the same as have more holes in a bell crank.
Suspension nerds (car, motorcycle, bicycle, etc) will certainly recognize the terms, rising and falling rate. |
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Al Evans
From:
Austin, Texas, USA
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Posted 1 May 2019 8:03 am
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| Ross Shafer wrote: |
The amount of pull changes throughout the arc that is made by the bell crank. Keep in mind as rising rate will increase the pedal force as it goes though its motion and a falling rate the opposite. We're talking pretty subtle stuff here, but its happening and can be used for fine tuning, though its is not the same as have more holes in a bell crank.
Suspension nerds (car, motorcycle, bicycle, etc) will certainly recognize the terms, rising and falling rate. |
Thank you! So the max pull would start a little before TDC and end a little after, and the minimum pull would start and end as far away from TDC as possible.
Given a spherical pedal steel of uniform density, of course....
--Al Evans
_________________
2018 MSA Legend, 2018 ZumSteel Encore, 2015 Mullen G2, G&L S-500, G&L ASAT, G&L LB-100, Godin A4 Fretless, Kinscherff High Noon |
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Ross Shafer
From:
Petaluma, California
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Posted 1 May 2019 9:27 am
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| By Jove I think you've got it! |
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