Leverage Selection
Theory
To change your guitar tuning you have to know a little something about selecting proper leverages at both the changer and bell crank ends of your guitar. Figure 3 shows these two parts as the guitar is upside down.
Changer: raise holes are rows A, B, & C. Row ’ÄòB’Äô is easier to pull than row ’ÄòA,’Äô but it also requires more movement to move a siring a given distance than does row ’ÄòA.’Äô
Lower holes: ’ÄòE’Äô is easier than ’ÄòD,’Äô but does not pull as quickly.
Bell crank: slot 1, that nearest the cross shaft, is the easiest but longest pull. As you move upward, slots 2, 3, & 4 become progressively stiffer but quicker; usually slots 2 & 4 are best suited for whole-step changes. All slots will accommodate half tone changes. The goals for selecting optimum leverage are synchronization of all changes on a pedal or knee lever and attain desired effort.
Procedure for selection
Determine which change on the pedal takes the most distance to be achieved.
General rule is that of the two strings tuned an octave apart, Figure 16, 5th and 10th strings B’Äôs, making the same change (Figure 16, pedal 1), the higher pitch (lighter gauge) string will require more distance to change.
In Figure 16 next to each pedal change there is a circled number. These tell you the factory-set leverages on a SCO-10 crown. Pedal 1 on this chart, both changes are B to C#.
By each C# is the recommended leverage. On the 5th string (A3) and on the 10th string (B3). This means the pull rod passed through row ’ÄòA’Äô of the changer and slot 3 for the 10lh string. Note: we already know, as discussed earlier in this section, that row ’ÄòA’Äô in the changer is a quicker throw but stiffer feel than row ’ÄòB.’Äô
Now in Figure16, pedal #1, both changes are positioned in slot 3 of the bell crank. To compensate for the greater distance the 5th string B requires to reach C# [than doesihe 10th string] we place it in the faster traveling row ’ÄòA’Äô and the shorter 10 string change in slower row ’ÄòB.’Äô This equalizes the two changes and allows them to pull as evenly as possible. At times equalization will have to be compromised on a certain pedal, either for quantity of changes or better equalization on a more used pedal. There are no ironclad charts that will cover ail tunings. When making changes, experiment with leverage and using the above guidelines; you will be able to obtain almost anything on your Sierra.