Double changer idea

[richard37066]

Mac -

I'm with you, Buddy! If designed properly, the strings should fall naturally on the center of the fingers. String tension is such that - only occasionally - one may displace the string from the center - except - when one gets careless and ends up with a ball of wire on a conventional tuner and displaces the string to one side or the other. This IS the reason for the grooves, isn't it? In my design, I'm going to turn the diameters of the rollers - to "guage" them - as opposed to grooving them. With all other things being equal, there should not be a problem with centering the string on the fingers. You'll no doubt put a small hardened steel pin in place of that little screw on the top of the tuner finger to locate the string.

Do you currently own a "keyless" guitar? I may be preaching to the choir here, but I'm mindful of the fact that, when changing strings, as hard as I might try to initially tension the string by hand and before tightening down the locking screw there are times when things just schlupp and I end up having to take up a bunch of slack before the string comes up to pitch. I mention this since your tuner finger might take a nose-dive resulting in the large adjusting screw being at an acute - and bad - angle to the tuner finger in operation. I might be jumping at ghosts here but its' something to consider. If the string in the picture is up to pitch then it would appear that your configuration is optimum.

Then all ya have to do is to take a file to some of the burrs and yer good to go! Instant tuner-changer!

Good thinking, my friend!

Richard

[Farmer]

Mac, you realize that you will be pulling both ends toward the middle, no biggie, just a little finaggling with the rods....Mike

[mac639]

Good morning Richard!
Now... rollers. I think I'd always groove the rollers a bit since they're narrow and the string would want to slip off rather easy. Now whether you make the groove gauged to match the string diameter that's up to you. Yes I have a keyless 12 string guitar I made last fall. The actual finger is the same as I put in the picture but it's a pull release guitar so it doesn't have the fancy lowering arm in the picture. I did put a pin on the finger since the string when secured under the securing bolt is way off to the side. The pin makes sure it's centered on the finger. Speaking of pins for use here or at the other end to put the string ball over, I use pieces of bicycle spokes. One used bicycle wheel will give you enough spokes to last a lifetime. You just have to make sure the ball will fit over the spoke wire as there are different sizes of spokes on bikes. I think the size is .075 inches diameter.
Mac

PS. Yes Mike I have to pull both ways but that's not a problem, just put the bellcrank bottomside up, some knee levers are actually pulling that way anyway so the bellcrank can go on the top as usual.
Mac

[richard37066]

Mac -

Bicycle spokes! Hooda thunkit!

Richard

[Bent]

Richard,
Regarding grooved rollers here are my 2 cents worth. I have done some research into this and have come up with the following...
The man who gave me the mill is an engineer, electrical engineer and machinist. During his university years he wrote a paper on audio properties for musical instruments as applied to metals and sonic relationships thereof.
He found that to get maximum sound transference and sustain from the string, it had to make contact with the roller at two points - one on each side of the groove, and NOT in the bottom of the groove.
Enter Richard Burton(Burt on this forum) He is an engineer as well. He sat down and figured out the groove angle and depth to make all the strings, regardless of their thickness, end up on a level plane. The formula is: On your lathe plunge a 60 degree cutter to a depth of 1.5 times the gauge of the string. Example: for a .012 string you plunge to a depth of .018.

I had heard other formulas for this which differed from Richard's. Therefor, thru my turner, whose son is a bit of a mathematician, I laid this problem on him. He came up with the same result as Richard. I will add that I didn't tell him about Richard's formula.

FYI, in case you would want to try it.

[mac639]

Bent... Burt's math makes a lot of sense. And your practical application of that makes it easier for us to actually make the slots right. In the last 40+ years I've repaired/restored many hundreds of acoustic and electric guitars. On acoustics I often make new bone saddles. I NEVER put any grooves in them, it'll kill the sustain quicker than anything. I have a set of nut files which I use to groove the nut...and doin' it right makes quite a difference in the sound.
I don't think any guitar repairman goes to great lengths to accurately file the nut. I try to get it so that the strings sit about halfway down in the slot, and let it go at that. Why would steel guitars be any different I wonder. I think it's mainly because of string rattle with the bar on the first fret. My Dobro has of course the same problem and grooving the nut alleviates it.
My 2 cents worth
Mac

PS.. Don't laugh at the bicycle spoke idea. They're made of pretty good steel, but not too brittle. You can cut them with a jewellers saw the best.

[Bent]

Mac, I believe the steels are different because here we are chasing the sustain...always preoccupied with sustain and tone. Never in my life have I seen a bunch of players who are such tone freaks as the pedal steel guitar player. That is why, if we figure we have one more thing that gives us better tone and sustain, then we go for that and apply it to our building process. Fact is...if the strings aren't at equal height, then the very real potential for buzz against the bar on the 1st fret is there.And where there is buzz..we can imagine what that does to shorten the sustain...or eliminate it. I'm not saying that every steel that don't have the gauged rollers buzz. But if we do something to bring the strings up to the same level, then we can rest assured that this problem is taken care of...and one more issue is dealt with to the best of our ability. Paul Franklin told us "the steel is as good as the SUM of all its parts." If there is a weak link there we seek to improve said link.

I agree that Burt's math "makes a lot of sense" as you put it. I believe it makes even more sense when I have got it verified independently by a math expert as well as an engineer.

No sir..I m not laughing at your bike spoke idea, just like I don't laugh at anything that comes from you

[Pat Comeau]

Just curious... what happens when you raise and lower the same string at the same time?...will it pull back the knee lever?, looks like a back and forth changer system!

Pat C

[mac639]

Pat...I'm not sure what you mean by a back and forth system, or if you're refering to something else altogether. Anyway, a double changer system, if you can get it to work right is way better than anything else in my opinion. As far as having a raise and a lower on the same string and getting it to be accurate on the middle note is probably easier with the double changer since the raises and lowers are totally independent and you can adjust the middle note with a simple screw in the linkage somewhere.
I could make it (the lowers) a push rather than a pull so that all the pedals and levers would be going the same way. I don't care much for "pushing" a rod rather than pulling it since pushing allows for flexing of the rod especially if it's very long. No problem pulling from either end towards the middle of the guitar. RKR and LKR normally pull towards the right so lowers on either of those doesn't require any reversing or anything.
Mac

[richard37066]

Bent -

I checked Burt's formula when he first posted it on the SGF some time ago. It's on the money.

As to the groove versus no groove quandary: - Show me the research. Provide a link to the paper that your friend published. I'll then compare his methodology and results to a couple of published papers regarding essentially the same subject. In a reference that I made to Georg some time ago it was determined that ANY obstruction to a vibrating string - even a changer finger - has a deleterious effect on BOTH sustain and tone - a true "knife edge" being the ideal. It would appear that a grooved roller provides the opportunity for twice the negative effect as opposed to a flat-topped roller. The angle across the "nut" would also come into play here.

That quote from Paul Franklin is most apropos here. Tone and sustain is the SUM of all of the parts. To make a blanket statement saying that a grooved roller is better than a roller without a groove implies that everything else is perfect, thus enabling one to make precise measurements which prove the hypothesis and, therefore, a superior instrument. I'd love to see your friend's laboratory model and review his measuring techniques - in particular, how he isolated the roller such that the measurement were restricted to that, alone. Without really knowing, I suspect that a "knife edge" or a fixed collet (your mill part) would afford a greater transfer of energy than a roller of whatever configuration. PSG's are far from perfect as we all know. Were they truly perfect then we wouldn't even consider things such as how the changer housing is fixed to the cabinet, a traditional tuning head versus a "keyless", materials from which to make the cabinet, the dimensions of aluminum side rails, etc., etc., etc..

I have maintained, from day one, that NO ONE knows what makes the PSG tick - because NO ONE has done the research in an effort to determine the contribution of the many constituent parts. This assumes, of course, that there is a sizable audience for such esoteric information thus the tacit need for the research. Given the myriad variables in the overall construction of the instrument, I find it challenging to accept the notion that a grooved/ungrooved roller nut has a MAJOR role in the overall tone/sustain equation. If, for example, a grooved roller contributes but much less than 1% to the aggregate sum of everything else, then it is something which is hardly worthy of consideration. In my case - and based upon published research - I believe the ungrooved roller to be closer to the ideal "knife edge". Will this generate a pronounced difference in the ultimate tone/sustain of the instrument? I hardly think so. The impetus for this is simply to make an attempt to design something which is the "best" that I can do - in all aspects of the design.

Given the above, I really think that we're making much too much of this roller thing. If one wanted a maximum transfer of energy (to where?) then it appears that all of the parts need be fused together into one homogeneous mass such that, when a note is struck, it jiggles itself merrily across the floor. In the absence of irrefutable evidence that "this" is better than "that" I concede to the idea that certain things fall into the category of "it makes me feel better". No good reason. No proof. It just "makes me feel better".

To each his own - as some are oft wont to say.

Regardless, I enjoy the bejabbers out of these discussions - whether I'm right or dead wrong. Doesn't matter. If I didn't enjoy all of this then I wouldn't be here and saying -------

Keep on truckin', my friend!

Richard