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Carbon Fiber Cello bridge


twcellist

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Bridge makers are all about giving the customer what he thinks he wants. If he believes red cars are faster, they don't argue, they sell red cars.

I prefer blanks with wider grain, or at least medium width. I think my failure rate is quite low, even from the rental fleet(!) because the bridges are cut properly, and customers like the sound, so where am I wrong?

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2 hours ago, Andreas Preuss said:

I don’t think so. Very cheap bridges have ALWAYS very wide grain and there is a reason for it. 

Maybe, maybe not. I have some very narrow-grained violin backs, and some with grain that is really wide, and stiffness and density are about the same.

I also have some bridges with widish grain, and also some with quite narrow grain, and the weight and "rocking frequency (measured) are about the same.

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Physical/acoustic properties of wood are not strongly correlated with grain width.

Perception of quality (and ability to command higher prices) IS correlated with grain width, which may also be related to more limited supply of close-grain wood.  There's lots of wide-grain stuff.

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2 hours ago, Don Noon said:

Physical/acoustic properties of wood are not strongly correlated with grain width.

Perception of quality (and ability to command higher prices) IS correlated with grain width, which may also be related to more limited supply of close-grain wood.  There's lots of wide-grain stuff.

Close grain relates to age, thus if a business, the customer pays for the added years. Like many red wines.

Also the mill likely ( with known woods ) has to travel farther and take greater resources to retrieve the wood.

Currently, given economic models shown in undergraduate schools, makes sense.

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On 4/15/2024 at 2:04 PM, Andreas Preuss said:

Sure.;)

I'm going to vigorously agree with David on this, and not just because today is his birthday, with the caveat that the top of the bridge is maintained in a position which supports it staying straight, which may not be at the angle it was originally cut.  For example, bridges which have a pronounced curve on their front (which I often reduce) and are flat on the back I will leave biased with a slight lean toward the fingerboard.
For a long time I've provided customers with a gauge that, if used, can provide the player with a very accurate way to position the top of their bridges.  For those who use it properly..., warping stops.  Many players don't however, no matter how often I demonstrate that it's worth doing.   The reasons seem to be varied..., fear, laziness or lack of awareness etc.

 

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19 minutes ago, Mark Norfleet said:

I'm going to vigorously agree with David on this, and not just because today is his birthday, with the caveat that the top of the bridge is maintained in a position which supports it staying straight, which may not be at the angle it was originally cut.  For example, bridges which have a pronounced curve on their front (which I often reduce) and are flat on the back I will leave biased with a slight lean toward the fingerboard.
For a long time I've provided customers with a gauge that, if used, can provide the player with a very accurate way to position the top of their bridges.  For those who use it properly..., warping stops.  Many players don't however, no matter how often I demonstrate that it's worth doing.   The reasons seem to be varied..., fear, laziness or lack of awareness etc.

 

I tried as well the method with giving customers a gage to check the right bridge position, taught them how to move it, if needed. Success rate was rather low which made me think of other solutions. 

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Wood's cross grain direction bending stiffness and strength is much lower than in the longitudinal direction.  So if you wanted to reduce bridge bending it would be much better to have the bridge's grain running vertically rather than horizontally.

This is never done so there must be a good reason why.  Anybody have some ideas why?

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40 minutes ago, Marty Kasprzyk said:

So if you wanted to reduce bridge bending it would be much better to have the bridge's grain running vertically rather than horizontally.

This is never done so there must be a good reason why.  Anybody have some ideas why?

It would at least have to be redesigned, otherwise:

Carving the feet would be a pain, and the toes would snap off

Legs would snap, or at least bend

Strings would slice into the wood and perhaps split off the outer parts

 

But mostly: because it is never done.  Tradition rules.

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53 minutes ago, Marty Kasprzyk said:

Wood's cross grain direction bending stiffness and strength is much lower than in the longitudinal direction.  So if you wanted to reduce bridge bending it would be much better to have the bridge's grain running vertically rather than horizontally.

This is never done so there must be a good reason why.  Anybody have some ideas why?

Perhaps because the strings would split the wood. 

 

There are three rotations of grain from which you could slice a bridge if you weren't paying attention. I had to rotate a cube of wood by hand to help me visualise this. I'm interested in the slice you get if you rotate the wood 90' on the axis which goes from side to side parallel to the soundboard. IE flip the cube forwards, towards the nut. The medullary rays will then go through the bridge from the front to the back face appearing as dots on each face. and the grain rings will be vertical when vuewed from the side.

 

If I had time I would cut one like this.

Maybe tomorrow ...

Edited by LCF
Cleaned up my act
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If we start this discussion, we could also look at rotations that are not 90 degrees.

For me, bending bridges are a non-issue. My violins have a 2002 bridge and one that is more than 100 years old, both straight. The only reason I ever had to replace bridges were either related to changes on the fingerboard, wishes to change the setup tonally, or the strings cutting the bridge. I look at my bridges regularly, putting them back in position is not that hard, especially not on a violin. 

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On 4/16/2024 at 10:10 AM, Michael Darnton said:

On wood cellos it's usual that a bridge cut to the correct angle will almost immediately lean forward because that's the way the top moves under string tension. So someone who knows what he's doing cuts the bridge leaning back a bit farther than he wants. Also, if you want to dig even deeper, the two feet do something different under string tension, so that can be compensated for in advance as well.

I notice the same effects on violins and violas and can feel it while fitting, and suspect you do as well.  When done fitting and the bridge is just sitting on the instrument without string tension, it would rarely look like it fits to someone who didn’t know what was going on.

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I'm pretty sure that this has been discussed before, and a quick search pops up in 2003. Have we discussed torrefying (heat treating) bridge blanks to harden/strengthen them more recently? Back then, Michael D. commented that the treated ones kind of fell apart under the knife.

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7 hours ago, Marty Kasprzyk said:

Wood's cross grain direction bending stiffness and strength is much lower than in the longitudinal direction.  So if you wanted to reduce bridge bending it would be much better to have the bridge's grain running vertically rather than horizontally.

This is never done so there must be a good reason why.  Anybody have some ideas why?

In this arrangement strings would sit on an end grain surface and would eventually split the bridge. Especially if the E string goes through the parchment there is nothing which could prevent that. 
 
Another weak point are the ears. The outer strings are trying to bend it down and could break the portion above the ears off. 

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The Carl Sandner German cello I bought in 1964 still has its original bridge and it is still straight. All it takes is regular checking its posture. I have checked all my bridges pretty much every time I removed then from their cases (or "stand" for the cellos for about 20 years).

Looks as though the fine tuners of that cello have been overworked without concern.

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On 4/17/2024 at 3:03 AM, David Burgess said:

Maybe, maybe not. I have some very narrow-grained violin backs, and some with grain that is really wide, and stiffness and density are about the same.

I also have some bridges with widish grain, and also some with quite narrow grain, and the weight and "rocking frequency (measured) are about the same.

One thing which can be different between wide vs narrow grain wood of the same type is the curvature of the grain, with larger spacings usually associated with larger diameters. Perhaps these are less likely to curve if the cut is not exactly quartered across the bridge.

The alternate wood orientation I described above would be slab cut with the strings resting  on the side grain so it might be more prone to bending, so what happens if you make a laminated bridge from 3 layers of maple? Does it throw the stiffness to weight ratio too far out for the usual range of bridge tuning manoeuvres? Could one design a bridge to suit? Or select tge wood accordingly? What is so special about maple that it is the preferred bridge wood?

Marty, you're excused from answering these questions :P 

Edited by LCF
Claritas
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15 hours ago, iNeedAnswers said:

Getting better customers?

 

I don’t think I had bad customers. Some of them were simply too scared to pull the bridge straight.

If I think about it, in Japan humidity in summer is pretty high, something between 80 and 90 percent. I think this is also a factor that bridges bent more easily when not kept absolutely straight. 
 

 

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8 hours ago, Andreas Preuss said:

If I think about it, in Japan humidity in summer is pretty high, something between 80 and 90 percent. I think this is also a factor that bridges bent more easily when not kept absolutely straight. 

No doubt that is a huge factor!
You say you've thought about better solutions, but have you arrived at one?  If so, would you be willing to share what they are.

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6 hours ago, Mark Norfleet said:

No doubt that is a huge factor!
You say you've thought about better solutions, but have you arrived at one?  If so, would you be willing to share what they are.

A bridge reinforced with two carbon fiber rods, mentioned before. 

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22 hours ago, Andrew Victor said:

The Carl Sandner German cello I bought in 1964 still has its original bridge and it is still straight. All it takes is regular checking its posture. ( ... )

I am not sure this stressed enough. Who do we blame?

This comment is important as the bridge has withstood a lifetime. If it is possible to stress checklists, bending bridges being one, then we ( thank you, Mr Victor ) might discuss educating the players.

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