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What about a CF bridge?
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=14683		 Page 1 of 1
Author:  erikbojerik [ Sun Nov 25, 2007 12:01 pm ]
Post subject: 
Any problems with a bridge made mainly of CF in an effort to lighten
the load?  I wouldn't want to epoxy one to a top, so I was
thinking of maybe laminating some CF to a thin wood base that would
then be attached to the top with HHG.



What say ye?
Author:  Rick Turner [ Sun Nov 25, 2007 12:18 pm ]
Post subject: 
Actually CF bridges have been around since about 1979. David Russell Young made them, LMI at least used to sell them.

If you hadn't noticed, they've swept the nation and are being used by every luthier but yourself...

Seriously, though, do it and let us know how it works out...You don't have to ask our approval to try anything!
Author:  grumpy [ Sun Nov 25, 2007 12:25 pm ]
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as Rick says, they've been around for a good while.

BUT! Don't go using one, expecting a mass savings. CF weighs more than any wood....
Author:  JohnAbercrombie [ Sun Nov 25, 2007 12:27 pm ]
Post subject: 
Shaping a CF bridge is not my idea of fun- the dust is nasty stuff, so wear a good mask.
Or, make a mold and laminate the bridge into it....

Let us know how it turns out!

Cheers
John
Author:  Jim Watts [ Sun Nov 25, 2007 12:41 pm ]
Post subject: 
I think everyone pretty well summed it up myself.
Author:  Hesh [ Sun Nov 25, 2007 1:23 pm ]
Post subject: 
I would not think that a CF bridge is a good idea.

In the high performance aircraft/fighter/helicopter industries CF is known to have good vibration insulator properties, particularly very high frequency vibration.

Add to this a layer of epoxy to laminate it to wood and epoxy, IMHO, cannot compare to say HHG for transmitting vibration freely.

Of course I have never tried this on a guitar and don't intend to either for the above reasons.  It just does not make sense to me.

Rick I am a huge fan of Ken Parker and spent some time with him at HGF.  I wanted to ask you if you know what he is using for his white fret boards and white bridges on his new acoustic line?  Although this may seem like a high jack depending on the answer it may be related.

Thanks
Author:  erikbojerik [ Sun Nov 25, 2007 1:45 pm ]
Post subject: 

[QUOTE=grumpy]as Rick says, they've been around for a good while.

BUT! Don't go using one, expecting a mass savings. CF weighs more than any wood....
[/QUOTE]



Right you are grump, I really should have looked up the specific
gravity of CF before attempting to germinate this kernel of a
thought...around 1.5 compared with most woods being <1.0...so I'd
need to reduce the size of the bridge by more than 33% in order to
start seeing any weight savings. 



Interesting that the fibers themselves are around 1.7, so the epoxy
medium actually serves to reduce the overall specific gravity of the
composite.



Hesh I've definitely noticed the kind of high-freq damping you're
talking about, after trying out a set of graphite piezo saddles on a
recent electric build.
Author:  Jim Watts [ Sun Nov 25, 2007 2:26 pm ]
Post subject: 
[QUOTE=Hesh] I would not think that a CF bridge is a good idea.In the high performance aircraft/fighter/helicopter industries CF is known to have good vibration insulator properties, particularly very high frequency vibration.
[/QUOTE]

First let me state that I think CF is probably not a good bridge material, at least not in the way we design standard bridges for the reasons stated above.

But I see this thing I cut out of Hesh's post quite regularly and can't help but wonder, in compared to what?
The aircraft industry is not comparing it to wood. I'm not so sure you can apply this information in the way it's meant here, at least the way I thought it was meant here.

It's true it does have good dampening characteristics, could be a plus, but I'll bet wood dampens even more. Also the speed of sound transmission through the fiber is much higher than wood.   
Author:  grumpy [ Sun Nov 25, 2007 2:30 pm ]
Post subject: 
Other than mass, I don't see any reason why it wouldn't be a great choice. It's relatively low damping, as Jim says, when compared to most woods.

Jim, while we have your attention, would bridge pins of CF be feasible?
Author:  Hesh [ Sun Nov 25, 2007 2:38 pm ]
Post subject: 
Jim buddy you may be right and knowing as I do what you do for a day job I am sure that you know much more about this than I do.

But.....steel also transmits vibration very well as well but look at the weight?

Carbon as a tonewood material may very well indeed transmit vibration very well, it's super strong, dense, and ultra light weight in and of itself.  But then mix in the epoxy resin which I believe is probably the issue in using a CF bridge.

But again, I am guessing and recalling all the Bell Helicopter parts where CF is used to fight high frequency vibration.  My stint with GE aircraft engines it was the same story - vibration kills and even titanium was replaced where it was safe to do so with CF to damp vibration.
Author:  Jim Watts [ Sun Nov 25, 2007 4:22 pm ]
Post subject: 
Hesh, I think maybe I didn't state myself very clearly, sorry about that. I just think we should state what material we're comparing the dampening to. And you right, it has a lot to do with the matrix for example a layup with very high resin content would dampen more, not be as stiff and be much weaker.

Mario - I think Cf bridge pins could be interesting, but I'm not set up to turn them. Interesting idea though.
Author:  Sam Price [ Sun Nov 25, 2007 9:09 pm ]
Post subject: 
The CF splinters are pretty nasty too. They kinda break in your skin when you're trying to pull them out. Gloves may prevent that, but make sure you clean up well afterwards.
Author:  Michael Dale Payne [ Mon Nov 26, 2007 1:47 am ]
Post subject: 
I suspect removal would be a headache
Author:  Billy T [ Mon Nov 26, 2007 6:00 am ]
Post subject: 
   There's more than one kind of CF. The standard form is the weave but there are unwoven strands as well as various length chop fiber(vis-a-vis tennis racquets).

   The advantage of CR would be to keep it hollow while maintaining appropriate glue area to soundboard. This would keep weight way below any wood while maintaining strength.

    The advantage of even aluminum(aluminium for you Brits ) is also a possibility which has a much higher strength/weight ratio, but engineering the bridge as well as production would be more than most in the luthier field would care or may be able to undertake easily.

    Any material stronger than wood could be used even steel, but it would seem quite flimsy. One has to get the mind out of the common mass/strength perceptions.
Author:  Jon L. Nixon [ Mon Nov 26, 2007 12:36 pm ]
Post subject: 
The old LMI "handbook" suggested that the CF bridge be laminated to a piece of maple veneer with epoxy, and then glued to the top with Titebond or whatever. Prior to gluing, you can stain the veneer line black with a magic marker. I never tried it.......
Author:  Kevin Gallagher [ Mon Nov 26, 2007 2:27 pm ]
Post subject: 
    I've inlaid a 1/4" X 1/4" CF insert into Ebony bridges an then cut the
saddle slot into the CF insert on a few prototypes. My intention was
simply to see what the tonal dfferences would be with that material
surrounding the saddle instead of the wood of the bridge.

   Not a big enough difference and not necessarily a major improvement
so it was abandoned quickly. The work nvolved could never justify the
change for me.

   I've also made bridges entirely from CF by both shaping them (not
recommended for anyone) and by laminating them into a ceramic mold
that I had a friend make in his dental ceramic lab. Both were nice even the
the laminated mold was much nicer in my opinion. Again, not enough of
an improvement for me to make the switch.

   Let is know how it works for you, though.

Regards,
Kevin Gallagher/Omega Guitars
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