From the DIYCorner: Increasing B-Pedal Travel and a Problem
Posted: 17 Oct 2007 7:46 pm
You are sitting at someone else's guitar and notice that the B-pedal has a relatively long, smooth feel while the one on your machine is short, jerky, and stiff. You want to match it with the feel of the A-pedal since the two are used together, constantly. Some guitars allow for minimal adjustments in attempting to increase pedal travel associated with the G# to A change. Described is a method for making the needed adjustment when others listed will not.
I had thought about making this change for a few years and had the workable remedy in mind. One day, I had the fortune of observing the underside of the guitar owned by Al Brisco and saw what was recognizable as the change for the desired effect. Originally, not knowing whether or not the change was worth it, I now had my immediate answer. I could hardly wait to get home to begin the modification.
There are about 5 methods of changing the amount of travel on a pedal:
1) Change the string; its gauge or whether it is wound or unwound
2) Change the location of the pull rod at the changer to a more desirable one (experimentation may be required here unless your are knowledgeable concerning the physics of the changer)
3) Change the location of the pull rod at the bell crank
4) Change the angle of the bell crank on its cross shaft (unfortunately, not generally available for square shafts) (the photo reveals many such on my machine)
5) Add an intermediate cross shaft with associated bell cranks, etc.
I shall be dealing with method 5) above.
Labeled Photo Parts
A - bell crank connection on B for connection to D
B - intermediate cross shaft
C - B-pedal rod
D - connection on B-pedal cross shaft
E - B-pedal cross shaft
F - connecting rod between B-pedal cross shaft and intermediate cross shaft
G - three G# to A bell crank pulls (the 12-string guitar has 3 of these)
We are applying the "law of the lever" on both the intermediate cross shaft, B (in photo), and the driving or B-pedal cross shaft, E. Pulleys and sprockets, essentially, obey this same law. I tend to think of a pulley as an "endless" lever.
As long as there is a greater distance between the cross shaft centre, B, and the connection point of the connecting rod, F, on this shaft compared to the distance correspondingly on the B-pedal cross shaft, we have increased the pedal travel required to pull the G#'s to A's. All three G# to A bell cranks are located on the intermediate cross shaft on my guitar. You need only place those pulls requiring more travel (than is possible on the B-pedal cross shaft) onto the intermediate shaft.
Without the intermediate cross shaft, we are left with adjusting from 1 to 4 above. Steps 1 to 4 above should be done prior to step 5 since they are relatively quick and easy modifications. If you have done steps 1 to 4 and still can't get enough desired pedal travel in their extreme conditions, step 5 offers almost unlimited access to more pedal travel. Also, increasing pedal travel reduces the force of the foot needed for activation.
Note, from the photo, that the intermediate cross shaft is a half shaft making room for the 20-degree pedal discussed under the heading, "The Comfortable LKL", on the Forum. I have discussed bell crank construction in one of the articles, if you wish to attempt making your own. You'll likely need some brass wristpin connectors as well. Start with the required diameter stock, drill a suitable hole crosswise for accepting the pull rod, drill out the centre with a lathe and tap thread for a short setscrew, then and only then, cut it to length (about 1/4") to match the thickness of the bell crank. Otherwise, contact you local steel guitar technician for required parts. Suitable setscrews can be obtained at specialty shops in almost any city. Phone around. Pull rods can be cut from 1/8" drill rod, available at specialty shops, also. Coat hangers are about 3/32" and ideal for the likes of Carter guitars or those requiring the 1/8" rods.
Fay
Considerations before making this change:
1) Check to see that increased travel of the B-pedal still allows for the foot to clear the B-pedal when depressing the A-pedal and coincidentally activating the LKR lever. Likewise, make sure that the foot can activate the B-pedal while moving LKL without interfering with the A-pedal.
2) Increasing pedal travel will increase the time to activate the pedal. Are you sure that the change will not “cramp your style”?
I had thought about making this change for a few years and had the workable remedy in mind. One day, I had the fortune of observing the underside of the guitar owned by Al Brisco and saw what was recognizable as the change for the desired effect. Originally, not knowing whether or not the change was worth it, I now had my immediate answer. I could hardly wait to get home to begin the modification.
There are about 5 methods of changing the amount of travel on a pedal:
1) Change the string; its gauge or whether it is wound or unwound
2) Change the location of the pull rod at the changer to a more desirable one (experimentation may be required here unless your are knowledgeable concerning the physics of the changer)
3) Change the location of the pull rod at the bell crank
4) Change the angle of the bell crank on its cross shaft (unfortunately, not generally available for square shafts) (the photo reveals many such on my machine)
5) Add an intermediate cross shaft with associated bell cranks, etc.
I shall be dealing with method 5) above.
Labeled Photo Parts
A - bell crank connection on B for connection to D
B - intermediate cross shaft
C - B-pedal rod
D - connection on B-pedal cross shaft
E - B-pedal cross shaft
F - connecting rod between B-pedal cross shaft and intermediate cross shaft
G - three G# to A bell crank pulls (the 12-string guitar has 3 of these)
We are applying the "law of the lever" on both the intermediate cross shaft, B (in photo), and the driving or B-pedal cross shaft, E. Pulleys and sprockets, essentially, obey this same law. I tend to think of a pulley as an "endless" lever.
As long as there is a greater distance between the cross shaft centre, B, and the connection point of the connecting rod, F, on this shaft compared to the distance correspondingly on the B-pedal cross shaft, we have increased the pedal travel required to pull the G#'s to A's. All three G# to A bell cranks are located on the intermediate cross shaft on my guitar. You need only place those pulls requiring more travel (than is possible on the B-pedal cross shaft) onto the intermediate shaft.
Without the intermediate cross shaft, we are left with adjusting from 1 to 4 above. Steps 1 to 4 above should be done prior to step 5 since they are relatively quick and easy modifications. If you have done steps 1 to 4 and still can't get enough desired pedal travel in their extreme conditions, step 5 offers almost unlimited access to more pedal travel. Also, increasing pedal travel reduces the force of the foot needed for activation.
Note, from the photo, that the intermediate cross shaft is a half shaft making room for the 20-degree pedal discussed under the heading, "The Comfortable LKL", on the Forum. I have discussed bell crank construction in one of the articles, if you wish to attempt making your own. You'll likely need some brass wristpin connectors as well. Start with the required diameter stock, drill a suitable hole crosswise for accepting the pull rod, drill out the centre with a lathe and tap thread for a short setscrew, then and only then, cut it to length (about 1/4") to match the thickness of the bell crank. Otherwise, contact you local steel guitar technician for required parts. Suitable setscrews can be obtained at specialty shops in almost any city. Phone around. Pull rods can be cut from 1/8" drill rod, available at specialty shops, also. Coat hangers are about 3/32" and ideal for the likes of Carter guitars or those requiring the 1/8" rods.
Fay
Considerations before making this change:
1) Check to see that increased travel of the B-pedal still allows for the foot to clear the B-pedal when depressing the A-pedal and coincidentally activating the LKR lever. Likewise, make sure that the foot can activate the B-pedal while moving LKL without interfering with the A-pedal.
2) Increasing pedal travel will increase the time to activate the pedal. Are you sure that the change will not “cramp your style”?