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[QUOTE=Mike Dotson] Seriously, an interesting idea and ya never know till ya try! [/QUOTE]

Exactly!
I applaud the effort, and even hope it works well and stays on there solidly. Pushing the envelope is always a good thing in my book, and anytime someone does something out of the ordinary, I think they are being a lot more brave than I am, and therefore it causes me to admire what they're attempting or doing.
Look at Mike Doolin's guitars...they're way different than anyone else's and that makes them all the more cool.

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Well thank you for the nice comments, and a big thanks for the engineering input. If I proceed with trying to refine the idea I will need to study the design as close as I can and your input may open my eyes to things I am missing.

As far as the pulley being fixed or moving. I believe it may move a small amount(if the soundboard compresses, and but it does not seem that it is a cut and dry model). If it was a fixed pulley and it had a mechanical advantage of 1. The friction generated by the saddle and wrap would be significant, thus reducing that value(I suspect pretty drastically). The fact still remains shear must be higher than a pinned bridge. However with the reduction of the peeling effect on the glue joint would be seem to make the trade off a good one. I would really like to hear what your thoughts are taking these factors into account.

On a possitive note: It is still looking good, and holding it's tune .

I have been putting a little thought into a bracing pattern that may be better suited for this type of bridge. If anyone has thoughts. I would sure appreciate the input.

Thanks again for all your comments!
Peace,Rich

Rich
it is always refreshing to see experiments. If we all
built everything identical nothing could ever be improved. Someone has to walk the other path.
So I pat you on the back for that.
I took a very carefull look at the pic of your bridge.
I can't see a pulley effect where the strings exit
the rear of the bridge. Im sure there is a slight one.
But the picture showing the front section with the ball
ends has very little tension, The low e string almost looks loose where it enters the front of the bridge.
Your second pic (blown up)makes it looks like some of
the ball ends are not pulling tight on there mount.
The reverse bend in the strings exiting the rear of the
bridge is where the bulk of the tension is.
I hope you can find these views as a helpfull observation, I have no intent to critcize your efforts.
I just hope this helps!

Tom

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[QUOTE=Tom Morici] .......The reverse bend in the strings exiting the rear of the bridge is where the bulk of the tension is.....[/QUOTE] That is what I'm thinking also. The wound strings (EADG) probably exert very little force after the bend. The non wound strings (BE) are probably slick enough to put some force after the bend. I wouldn't expect there to be much dynamic changes when played. especially with the wound strings. When you are making tight bends like that, a bearing is needed if you want the tension to transfer past the bend. Just thinking out loud and offering a suggestion - take it or leave it.
Pretty cool looking design.
Keep up the inovation!

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[QUOTE=Tom Morici] Rich
it is always refreshing to see experiments. If we all
built everything identical nothing could ever be improved. Someone has to walk the other path.
So I pat you on the back for that.
I took a very carefull look at the pic of your bridge.
I can't see a pulley effect where the strings exit
the rear of the bridge. Im sure there is a slight one.
But the picture showing the front section with the ball
ends has very little tension, The low e string almost looks loose where it enters the front of the bridge.
Your second pic (blown up)makes it looks like some of
the ball ends are not pulling tight on there mount.
The reverse bend in the strings exiting the rear of the
bridge is where the bulk of the tension is.
I hope you can find these views as a helpfull observation, I have no intent to critcize your efforts.
I just hope this helps!

Tom[/QUOTE]
Tom,
      Thank you for the kind words. I think the pictures may be deceptive. I am absolutely sure the ball ends are seated, and that the strings are all tight from the bridge to the stop piece. I have had the guitar tuned up for several days and it is holding it's tune very well. If there was a binding issue it would have been painfully obvious due to tuning issues. I had a great deal of concern about that very problem while I was shaping the bridge. I had even thought about laying a brass pin or inserting a piece of graphite. After shaping the radius at the wrap. I thought it had a good chance of working(so I gave it a go, with fine results). I think it would be a good idea to address this area if I used a different wood(say mad RW vs the Blackwood I used here).

From the comments so far... I have noted the concern about the tail piece footprint being a potential week link, Possible issue with the bridge glue joint(footprint being reasonable), concern about binding at the wrap around area, concern that the wrap around area is a movable pulley with a mech. advantage of 2(doubling the shear on the bridge glue joint).

I guess the biggest variable to me when designing was the effect of the wrap. It seems that is kinda what I am hearing from some of the respoces also. Mechanical advantage is diminished with friction, and extream friction would lead to binding. From my observations friction is absolutely present, but not so much that it has caused binding issues. I wish I could quantify the shear as that would probably tell me a bit about the level of friction also. Maybe a test model could shed some light(I just have to figure out how to put one together.

Peace,Rich

I too am an engineer. The force on the bridge to shear it off would not be double. The strings do not suddenly pull twice as hard due to the way they are terminated. But, the string ends are sharing in holding the load, so they would be providing half of the full load. And since they come out of the bridge at a point closer to the soundboard, the moment arm would be less. Wouldn't this lead to less rotational force on the bridge?

[QUOTE=BarryDaniels] I too am an engineer. The force on the bridge to shear it off would not be double. The strings do not suddenly pull twice as hard due to the way they are terminated. But, the string ends are sharing in holding the load, so they would be providing half of the full load. And since they come out of the bridge at a point closer to the soundboard, the moment arm would be less. Wouldn't this lead to less rotational force on the bridge? [/QUOTE]

Would this lead to less rotational force? Oh yes, That is my main motivation in doing this("Balance").

Peace,Rich

[QUOTE=BarryDaniels] I too am an engineer. The force on the bridge to shear it off would not be double. The strings do not suddenly pull twice as hard due to the way they are terminated. But, the string ends are sharing in holding the load, so they would be providing half of the full load. And since they come out of the bridge at a point closer to the soundboard, the moment arm would be less. Wouldn't this lead to less rotational force on the bridge? [/QUOTE]

It does make a difference, because your strings terminate at a different anchor point than the bridge... You will have to carry the full string tension between the bridge and the string anchoring plate. So the bridge has to resist the pull from the bridge-to-nut part of the string, and from the bridge-to-anchor part of the string.

You're also going to actually have more torque from the tension of the strings from the bridge to the anchor plate. Not as much torque as the strings to the nut, since it's closer to the sound board... But in the end you have both sets of strings pulling on the bridge, above the soundboard, applying a torque in the same direction.

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Jonathan Kendall, Siloam Springs AR

Here's a pic to clarify (or confuse some more) what I'm talking about.



M is the moment, or torque, that is being applied to the bridge.

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Jonathan Kendall, Siloam Springs AR

I've been watching this thread with interest, but have not had the time to provide useful input. Unfortunately, I still don't have the time in the near future, but I can say this. Jon (letseatpaste) has the right general idea, but you have to remember to crank in the sines and cosines (horizontal and vertical pressures) at the bearing point on the saddle.

It may help in understanding to refer to a section I wrote for the book "Left Brain Lutherie" by David Hurd. Look up the section on bridge forces and there's a page or two of analysis that should help you. My analysis does not depict the bridge configuration in question, but could easily be expanded to do so. Though I wish I did, I unfortunately do not have the time to look into it myself right now.    Sigh ....

Jon,
   You drawing is a very clear picture of movable pulley with a mechanical advantage of 2(very easy to follow). What does friction on a pulley do to the mechanical advantage? This is what muddys the water for me. Also your drawing does not show how the strings actually have an upward break angle at the front of the bridge. I am not sure what effect that may have on the shear. I am going to attach a link to a PDF I had made a while back that shows the basic concept in section.

For the sake of argument. Assume the bridge itself is bolted down and has no chance of being pulled off. Would I be correct in saying the soundboard is still going to see the typical string tension(or close to normal, abviously the twisting will alter how the tension is seen normally).

What do you think about the reduction of twisting force that normally supplies a non linear pull on the soundboard(distorts soundboards, peels bridges off). My initial thinking was that getting a more linear pull on the soundboard would allow it to react more effectively(from a less distorted or pre-loaded position). This was my main motive in trying this experiment. I hope I am describing this effectively.

Peace,RichPDFfryovanni39051.6242476852

There is of course a lot of friction in the bridge. This means that the tension between the bridge and tailpiece will be lower than the tension between bridge and nut. I couldn't understand Barry's post, but if the bridge were an ideal fixed pulley the string force is doubled. Were you talking about friction, Barry, or about the anchor points? You seem to be treating the design as one in which the strings pass through the front of the bridge and anchor against it. But this is an independent anchor.

What this means for the design is a double-bind: to the extent that it works as intended to counter the torque by pulling up on the front of the bridge (I'm not commenting on whether I agree that this is desirable), it increases the shear on the bridge's glue joint. The original post said Rich was trying, in effect, to approximate a pulley by reducing friction in the string through the bridge, so I have been granting that he succeeded in this for purposes of discussion.Howard Klepper39051.5956944444

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http://www.klepperguitars.com

When all else fails, clean the shop.

Howard,
    If my understanding of how a string works is correct. The tension is equal throughout it's length unless you bind it. If you have friction around a point the string will try to overcome this friction. If it is not bound it will overcome that friction and equalize. If the friction at the wrap was too great I would have tuning issues(much as with a poorly made string nut). Friction is most definately going to be present, but it was not great enough to bind the string(thus tuning has been fine). Every pulley does have friction. If I tried to lift a load across a pulley with as much friction as the wrap on this bridge I would have no where near a mechanical advantage of 1. I suspect if I attached a load to the bridge(assuming the bridge was free to move with the load attached to it) and tried to lift the load. I suspect the friction would give me a mechanical advantage less than 2(which requires the pulley to have no friction).
Also maybe I could get a confirmation on my thinking about how a movable pulley gets it's advantage. When you have a movable pulley with a load attached and a length of rope with one end fixed above the pulley. Then you pull the rope 12" the load is lifted 6" thus giving you a 2 to 1 advantage. Is that correct?

Peace,Rich

There is friction, but I would say it's relatively insignificant... And besides, you would want to have equal tension all the way to the tail piece... Or else the guitar is going to go out of tune all the time, like it would if the string were binding at the nut.

There is no way to eliminate the strings torque on the bridge and still keep the string anchor above the top of the guitar (unless you anchor at the tail piece).

Pete mentioned something important, which is that the string tension as it wraps around the saddle is going to also add some torque on the bridge causing it to want to tip towards the soundhole... Not from the direct pull/tension of the strings, but because the strings will apply pressure to the saddle because the string "wants" to be straight. This applies to a traditional bridge, or the bridge this thread is about.

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Jonathan Kendall, Siloam Springs AR

I think I may have been wrong. The diagram appears to indicate the force is doubled (assuming the stated frictionless pivot) and I think I agree with this.

Yes, the force pulling the bridge toward the nut is double, But don't forget the force on the triangler string anchor. It has normal string force on it pulling toward the end pin. That means the overall force on the top is in line with a standard bridge.

The issues as I see it are, are the footprints of the bridge/string block big enough to produce an adequate glue joint?
Should the glue be epoxie?
Does the arrangement produce an Acoustic Advantage?

Other than that it is pretty cool and shows some real innovation

Joe Beaver39051.8860763889

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Maker of Sawdust

Rich
Thanks for clarifing my mistake about seeing the ball
ends of the strings not being tight to the mount.
I must ask how your design is that much different
to the last one we all commented on. Please look at this
picture that clearly shows the A and D string ball ends
not snug against the front of the bridge.
Your design is similar,even though you have less binding
of the string as it exits the rear of the bridge.
It would still have to reduce the pull on the ball end.
I also see 3 other points that I feel reduce the pull
on the string ends. Comments please.
Great Post,

Tom

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Rich,

It is amazing just how many of us will sit back admiring a great new idea and pondering the question, "now why did'nt I think of that".

The fact that you are prepared to get off your behind and commit your time, material and efforts into researching your ideas insures that you will not remain among the ponderers.

When you do crack that egg, we shall all understand why it was you who did it.

Well done mate.

Cheers

Kim   

Tom,
   I suspect that picture could also be a little deceptive. However I recall looking at the bridge you are showing, and the strings took a hard turn into a metal sleeve. I could imagine it would have the potential to bind a string(especially a wound string). The strings wrap around a much larger and smoother radius on my bridge(more akin to a wrap around TOM). Like I mentioned before. As long as the strings can overcome the friction at the point they wrap(not bind)friction will be equal throughout the length of a string.

      The biggest difference between the bridge in your picture and mine. Is that I am attempting to counter some of the twisting force that lifts the rear and pushes down on the front of a normal bridge. I am attempting to do this by having the strings break at an upward angle from the bridge to the stop piece(lifting the front of the bridge). At the same time I am countering the twisting force I am also trying to clamp the saddle harder between the the two oposing forces. The hope would be that a better coupling or grip on the strings would improve energy transfer to the soundboard.

    There are a few other things I am doing with this guitar. Hoping to see improved performance. My neck is raised and has positve angle. I have a few little mods in the box also, but I didn't really want to muddy the water much more with those elements.

    If it fails tomorrow I will be happy. It has been fun, and it sounds and plays great. I will definately try to use what I am learning on the next build. I really appreciate all you guys sharing your knowledge.

Peace,Rich

Rich
Thank you for your response. I did consider that your design had the rounded exit point vs the sharp one in the pic I posted. I am glad you allowed us to express
what we felt we where seeing.
Keeps us thinking and that can never Hurt.
(Unless Im tired )

Tom

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