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From The DIY Corner: The Comfortable LKL

Posted: 14 Oct 2007 9:06 pm
by Fay Reid
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Explanations and Rantings

Posted: 14 Oct 2007 9:08 pm
by Fay Reid
I had been practising my guitar for a few hours/day (say, about 6 or so) for weeks on end. The outside of my left knee was becoming very agitated and sore, the result of the constant rubbing of the knee against the associated lever. The first job in finding a solution to a problem is defining the problem itself. The problem boiled down to the latteral rub of the lever on the knee. The solution, then, would be to eliminate this latteral rub. It soon became apparent that the knee and the lever were moving in two different directions. Since I couldn't change the direction of motion of the knee, I had to look at the guitar. The solution resolved itself very quickly; just rotate the action of the lever a few degrees to accommodate the direction of motion of the knee. Since the player tends to be seated to the right of centre of the guitar, the right knee does not share the same problem. Even the rightward motion of the left knee has no ill experiences with this problem since the motion of the left knee to the right is tending to correct for the problem angle.

The angle of my left upper thigh was 20 degrees from the knock-kneed position, so I simply rotated the lever, in question, 20 degrees. Photos of the underside of the machine should be self-explanatory.

If there is no room for the modification, one of the crossrods will have to be cut off and a bearing supplied if it doesn't already exist. I was lucky since MSA had supplied it whith the centre bearings down the middle. A setscrewed aluminum doughnut can be inserted to the inside of this bearing to keep the half-shaft from sliding out. I was lucky to be able to use a functional bell crank. (See photo.)

There may be extra nylon bushings with you guitar that you can use to construct the end bearings for the 20-degree shaft. Drill a couple of holes in two short lengths of angle aluminum to accept the two bushings. Add the lever with any bell cranks to the two shafts, as in the photos, along with brass wrist pins and bent pull rod.

I made a jig for forming the outside of the nylon bushings on a metal lathe, then the bushing on the lathe ,as well. Since I had used the extra supplied MSA bushings in other projects on the guitar, extras were required. Worn out snowmobile runners are good sources for any nylon required.

Bell Crank Construction
Bell cranks can be made from 5/16" aluminum plate or 3/8" in a pinch. All you require is a drill press, hacksaw, and an appropriate threading tap for the setscrew that holds the bell crank on the cross shaft. Cut out the reqired shape, drill all holes, then with two blades in your hacksaw, position the bell crank in the vice such that when using the vice jaws as a guide, you cut one inner surface of the slot that accepts the 1/8" pullrod. Reverse the bell crank in the vice and as before cut the other inner surface. By using two blades instead of one, you'll have very little material to remove in the centre. Use the same two blades to make the cut for the friction fit on the cross rod. Since you've already drilled the hole for accepting the setscrew and countersunk the upper half of hole slightly over-size, tap the lower half. The setscrew will twist down and hold the bell crank to the cross rod. (Be extremely careful not to snap the tap, since you are on the last step of construction!)

It's amazing what one can make with a drill press and a hacksaw! I think each bell crank takes me about 3/4 of an hour to make, or about the time it takes to get ready to head for your local machineshop.

I must admit that I am very disappointed with modern steel guitar manufacturers on two fronts. One is that steels are not being made with the 20-degree lever. This is an absolute must; what could make more sense? I realize that some put an angled face plate on the LKL lever, but it does not address the real problem. A friend and fellow player stated that all steels should be made with this modification. He has a modern machine that is next to imposible to modify without commercially made parts, if he can find them.

The second is the construction of guitars with square cross shafts. Now any modifications, such as that described above, are next to impossible for the average owner/player. How does one make bell cranks for these machines or cut a shaft in half and support the cut end with a square-bushed bearing. Your purchase was sold as a quick method for modifying the guitar compared to a round-shafted machine. I guess it depends on the type of modification being made, doesn't it? The wheel has been invented, let's use it.
Fay

Take a close look at the photos. You may be able to see other modifications such as; half stop, tuneable splits (2 on this guitar.), a third raise on a changer that was only made for two. There was a 4-raise on it at one time until the copedant was changed to eliminate it.

I have discussed most of these modifications before on the Forum, but am doing so again since I have diagrams and/or photos to better explain.

Some people are hesitant to modify their guitars, etc for fear of making a mistake. Thankfully, some people in the past as well as manufacturers have done so to give us the great instruments that we play today. My phylosophy..."If I happen to make a mistake, the educatonal experience that I gain from the error is well worth the cost to repair the damage". Anything can be constructed; it's just a matter of the amount of time to do it. Go for it!

Posted: 15 Oct 2007 5:08 am
by David L. Donald
My ol 82 Pro II Shobud has that angle also.
Seemes to make perfect sense.

Posted: 15 Oct 2007 10:23 am
by Bent Romnes
Fay,
Eddie Fulawka told me he angles the knee levers...just the lever itself mounted on a straight shaft as I remember it.
On my homebuilt I didn't angle any of them. Funny thing is, LKL works as smooth as butter and can't see the sense in angling it. Might be a different story for the other ones.

I don't really get the beef you have with square cross shafts. Everyone that I have read about, uses square or hex cross shafts. I contend that you don't need center support as long as you use 5/16" steel stock. Cutting a bellcrank is easy; just takes a bit more elbow grease. Instead of drilling a hole, you have to hacksaw a 5/16 slot.
By the way, there is a way to make a bellcrank that goes on a round shaft without having to dismantle the shaft.
Look here:
http://bb.steelguitarforum.com/viewtopi ... ht=blanton


and a pic of the bell crank:

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From this pic, all you need is to drill/cut a half-round hole and use a set screw. I can't see any reason why these crank holes can't be applied to any type crank, not only the Blanton type.

The only 'bad' thing about a square cross shaft is that you of course have to turn the ends round. In other words, it makes it a job for the lathe, something hacksaw guys like you and I normally don't own. But that was the only thing I had to farm out when I made my home built :-)

Blanton Bell Crank - Reply for Bent

Posted: 15 Oct 2007 11:53 am
by Fay Reid
If manufacturers applied the Blanton bell crank to their guitars, I could live with it since it overcomes the problem of trying to make pull rod starts, on the same shaft, all occur at the same time. The first attempt I saw to allow for this adjustment was on a Russ-ler (I think) guitar played by Jeff Newman in the mid to late '70's. The construction of the bell crank was a little cruder and did not allow the effective force distance (distance from crossrod centre to pull rod) to fall to zero as the Blanton does. However, I noticed the construction those many years ago and determined their intended use. It didn't take long to figure out that I could accomplish the same by angling the bell crank on its shaft. The Blanton has the added advantage of making minute adjustments and in the desired direction. I'm relegated to diong the angle adjustment by trial and error. And, I have to get under the guitar with an Allen key each time I do it. I wish that I had thought of the Blanton...a lacking of the grey matter? I though that I had solved the problem, so wasn't looking for a better solution. ( I think I already mentioned something about defining the problem. If you don't recognize that there is a problem, no better solution is ever forthcoming.)

A slight misunderstanding of the centre support... I agree that a centre shaft support is not necessary as long as the cross shaft is consistant in its flex. MSA probably overdid this aspect but it did give me a convenient method for cutting one of the shafts off to make a half-shaft giving room for the 20-degree LKL lever. The bearing was already there, but it would be a relatively simple procedure to fabricate the supporting structure with nylon bearing (same as for the 20-degree pedal). Performing this on a square-shafted guitar is a little meaner. The end of the shaft would have to be turned round.
Fay

For Bent

Posted: 15 Oct 2007 12:00 pm
by Fay Reid
Sorry, Bent. I missed your last comment concerning the machining of the square shaft to round. You had already covered the issue.
Fay

Posted: 15 Oct 2007 12:03 pm
by Steve English
That's some radical positioning of many of the bell cranks underneath your guitar! :whoa:

What's the benefit of that?

Reply for Steve

Posted: 15 Oct 2007 1:30 pm
by Fay Reid
The angling of the bell cranks is an attemp to make all pulls on the same cross shaft (pedal or lever) start at the same time. (Pulls all inherently stop at the same time.) All strings do not start their pulls at the same instant because of the varying string parameters such as material, diameter, etc. Strings are not identical so require different distance of travel to get them to the desired pitch, say, G# to A. Strings are also pulled (neg or pos) through different musical degrees; some a half tone, others a full tone or more, all activated by the same pedal (lever).

The real question is...Why do I want all pulls to begin at the same time?

It feels smoother under foot. One string's starting half way through anothers travel make the pedal feel as if its a half-stop because of the extra force required once the second string starts it pull. In fact some manufacturers use this idea for construction of the half-stop. No problem here, but I wouldn't like this feel on all pedals!

The force required to pull the lagard is more since according to the law of the lever, a shorter distance over which a force is activated reqires a larger force...Half the distance, twice the force. The larger diameter strings tend to require vary little pedal travel (force distance) to get them to pitch, so they start much later in the pedal travel. This makes the force to move them rather large campared to, say, the high G# string. Your foot has a tendency to stop, particularly as it gets near the end of expected pedal travel when it feels the increased resistance. If it stops prior to the true end of travel, all associated strings are out of tune. I have had this happen, not under these conditions, but where there is a little bit of extraneous resistance in the mechanism. As a corollary, the least amount of pedal force to activate the specific pull occurs when all strings on a pedal start at the same time.

Lets imagine that the 6th string doesn't start until the 3rd string is partially through its travel. The first part of the pull is so slight that it may be hard to perceive. If your foot is resting even lightly on this pedal, the high G# string will be a little higher! Adjusting your guitar to make the 6th string start with the 3rd string has a tendency to prevent this since there is more force needed to start two strings than one. So, starting the lower G# string sooner must be compensated by making its bell crank have a diminished rate of pull. Of course, this can be done by angling the bell crank from the 12 o'clock position down towards the 9 o'clock position. 20 degrees of effective pull at the 9 o'clock position has a much smaller horizontal component to the pull than that at the 12 o'clock position. Most of the motion at 9 o'clock is vertical while that at the 12 o'clock position is hoizontal...the direction of pull rod travel.

To answer your question: I angle the bell cranks to get the smoothest and, perhaps, easiest possible action from the machine. I don't need any physical handicaps while playing, the mental ones are sufficient! It's analogous to driving with seven cylinders funcional on a V8. You'll get to your destination but you'll be disturbed by the engine's performance because you are able to recognize the lack of performance. There are some folks who don't recognize the difference and still others who do but don't care. I want my machines all working at peak potential.
Fay