If there was a logical way to make a carbon fiber bridge work well on a double bass, I think Luis and Clark would do it. 
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Double Bass Carbon fibre bridge...?
- Thread starter swingingoodtime
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If there was a logical way to make a carbon fiber bridge work well on a double bass, I think Luis and Clark would do it.
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Really? They don't seem to have figured out a logical way of building a carbon fiber bass.
If there was a logical way to make a carbon fiber bridge work well on a double bass, I think Luis and Clark would do it.
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+1
They went to all the trouble of making a CF bass, yet stuck with a wooden bridge. Theres likely an untold story about failed experimentation with a CF bridge. I suspect (aside from the fabrication challenges) that the CF doesnt perform well as a medium for transferring string vibrations to the top of the instrument. And this all speculation, of course.
But in WWII years they made aluminum basses. Even in those, the bridges were maple.
Bottom line wood is a versatile material that is cheap, easy to use and works well for the application since it is easily modified. If you want to mess w/bridges and material density you could try fabricating a series of bridges made from various woods similar to the folks that mess w/endpins. Then there are luthiers that remove the wings and dial in the bridge by removing material etc.
- Aug 1, 2005
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Ah! Here let us indulge for a moment in a tangent which might be interesting. The luthier fits the bridge feet to an uncompressed top. No matter how well he carves the feet, the fit will change when string tension is applied. Of course corrections can be made if there are obvious discrepancies, bend can be anticipated, and also the maple feet are flexible and will adjust themselves, but if the foot to top fit is done with a thin layer of some very viscous epoxy paste, then it could be done on a sprung top, possibly better matching its surface.
I can already shoot holes in this idea as I'm writing it, but it is nice to have a fun thread to "what if" on
Hi.
Hypotetical, obviously, but...
When I fit the bridge, I always pre-spread the feet and I also always re-shape the feet after checking the fit with a strung and tuned to pitch bass. During the tuning, I also make sure that the top or the bridge doesn't bend as much as to dent the top. Obviously.
Granted, I have had no formal training to do so, and I have only fit a couple of bridges, but it just makes sense.
Shaping an unsprung bridge OTOH doesn't.
The "epoxy method" works well also IMLE, on pizz/slap BSO's anyway
.
Regards
Sam
Hypotetical, obviously, but...
When I fit the bridge, I always pre-spread the feet and I also always re-shape the feet after checking the fit with a strung and tuned to pitch bass. During the tuning, I also make sure that the top or the bridge doesn't bend as much as to dent the top. Obviously.
Granted, I have had no formal training to do so, and I have only fit a couple of bridges, but it just makes sense.
Shaping an unsprung bridge OTOH doesn't.
The "epoxy method" works well also IMLE, on pizz/slap BSO's anyway
.Regards
Sam
If there was a logical way to make a carbon fiber bridge work well on a double bass, I think Luis and Clark would do it.
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I reckon it's more a case of: "If there was an economical way to make a carbon fiber bridge work well on a double bass, I think Luis and Clark would do it."
On mold fitting (aka 'the epoxy method'): if done well, that gives an absolutely perfect fit to the un-loaded top. Half a year ago I gave a guideline for doing that, but that was considered 'probably the worst advice on the internet', so I removed that post. However, doing it stressed is practically difficult to give the desired result.
On CF-epoxy composite as bridge material: there may still be, after hundreds of years, improvements possible to a violin/db bridge. Particular areas of improvement could be: strength (wooden bridges break), but maybe also tonal improvements are possible. However, if you make a composite bridge with the same dimensions as a conventional one, it will be heavy and VERY hard. Typical values for E [GPa] & SG [g/l] are:
maple, along grain: 10 & 0.665;
maple, across grain: 0.6 & 0.665;
CF/epoxy (unidirectional): 150 & 1.780.
An important aspect of a violin bridge is filtering-out unwanted high frequencies, particularly coming from slip-stick interactions between bow & string. The eigen frequencies of the vibration modes of the bridge should be tuned to these high frequencies, and the eigen frequency of these oscillation modes is typically proportional to SQRT(E/SG). So I suspect that for a CF bridge you'd have to make the parts that are bending in these oscillations substantially thinner (typically a cross-sectional area reduced by a factor 2 - 3). The bridge should then still be stronger than a wooden bridge though.
Another aspect is absorption of energy, or damping. This too is frequency dependent, but I haven't a clue about quantification.
So it may be possible to make a better db bridge out of CF composite, but I suspect quite a bit of trial & error will be required in the development phase (or it will be a dud). Hence high development costs, and a mediocre Possibility Of Success. And then there are all the advantages of wood, as easy fitting, low cost, ... as mentioned earlier.
On CF-epoxy composite as bridge material: there may still be, after hundreds of years, improvements possible to a violin/db bridge. Particular areas of improvement could be: strength (wooden bridges break), but maybe also tonal improvements are possible. However, if you make a composite bridge with the same dimensions as a conventional one, it will be heavy and VERY hard. Typical values for E [GPa] & SG [g/l] are:
maple, along grain: 10 & 0.665;
maple, across grain: 0.6 & 0.665;
CF/epoxy (unidirectional): 150 & 1.780.
An important aspect of a violin bridge is filtering-out unwanted high frequencies, particularly coming from slip-stick interactions between bow & string. The eigen frequencies of the vibration modes of the bridge should be tuned to these high frequencies, and the eigen frequency of these oscillation modes is typically proportional to SQRT(E/SG). So I suspect that for a CF bridge you'd have to make the parts that are bending in these oscillations substantially thinner (typically a cross-sectional area reduced by a factor 2 - 3). The bridge should then still be stronger than a wooden bridge though.
Another aspect is absorption of energy, or damping. This too is frequency dependent, but I haven't a clue about quantification.
So it may be possible to make a better db bridge out of CF composite, but I suspect quite a bit of trial & error will be required in the development phase (or it will be a dud). Hence high development costs, and a mediocre Possibility Of Success. And then there are all the advantages of wood, as easy fitting, low cost, ... as mentioned earlier.
I made a EUB using very dense materials including a composite material (dymondwood) bridge. The result sounded more like a fretless BG. I then added cork under the bridge and neck/body joint for dampening which improved the sound. My simple experiment showed me that dampening is essential for a DB sound at least in an EUB. MY hunch is a CF bridge might be too bright and harsh sounding on some basses and may improve clarity on dull basses??
The biggest difference between an EUB and a acoustic DB is that the latter emits energy in the form of sound. Therefore each tone decays faster on a DB than on a EUB, where the energy stays in the instrument. The pickup takes a bit, but very little (your LH fingers take much more). The cork may simulate the acoustic decay, to some extent, particularly with a low breakover angle.
Rotating the grain in the bridge (so that it is perpendicular to the table) also helps in brightening-up a dull instrument, because of the substantial difference in stiffness (E) between the two directions. However, arco suffers badly (but I tested this on a db that was not dull at all). For such a bridge, still recommend conventionally oriented feet or soles for strength & to prevent wear on the table, and on basses with a strong curvature in the table (so that the legs get spread apart) you run the risk of cracking the bridge lengthwise. You can prevent that by including a tension patch in the top of the leg arch. Otherwise, a bridge with a grain orientation like that is a lot stronger, a conventional break with a crack parallel to the table will not occur. But just to share my experience on this, I consider that test bridge that I made a dud because arco is worse (admittedly with spiro's). Pizz has more brights too, but there it is not so bad, and you could view it as a bit more presence. But I don't need it.
Edit/add: Robo & T-Bird, with a "sprung top" and a "sprung bridge" I suppose you mean that the top is loaded (or stressed) with the downward force of the strings? I feel that is difficult to do with a mold fit because of the following 3 reasons. Firstly I use a protective film over the top, cause the last thing you want is to glue a bridge to your top. But I fear the protective film will break because of the high point loads between the highest points of the feet and the table. Secondly, even if the film does not break, you will deform the top (= the mold) at those highest points, so the shape you create will still not yield a constant surface pressure over the contact area. The low areas remain virtually un-loaded, because the viscous epoxy paste will continue to flow (viscously) away, just until all pressure is gone. So then it will not bear any load. It will do that even if it has a very high viscosity, only with a high viscosity it will take longer (that's the third reason). It is practically extremely difficult to time the setting (or gelling) point so that you end-up with an even pressure profile (unless that pressure is 0, so un-stressed). Maybe you could improve by doing it iteratively, starting off with an un-stressed fit and gradually increasing the load. Or re-work the un-stressed fit mechanically, if required.
Rotating the grain in the bridge (so that it is perpendicular to the table) also helps in brightening-up a dull instrument, because of the substantial difference in stiffness (E) between the two directions. However, arco suffers badly (but I tested this on a db that was not dull at all). For such a bridge, still recommend conventionally oriented feet or soles for strength & to prevent wear on the table, and on basses with a strong curvature in the table (so that the legs get spread apart) you run the risk of cracking the bridge lengthwise. You can prevent that by including a tension patch in the top of the leg arch. Otherwise, a bridge with a grain orientation like that is a lot stronger, a conventional break with a crack parallel to the table will not occur. But just to share my experience on this, I consider that test bridge that I made a dud because arco is worse (admittedly with spiro's). Pizz has more brights too, but there it is not so bad, and you could view it as a bit more presence. But I don't need it.
Edit/add: Robo & T-Bird, with a "sprung top" and a "sprung bridge" I suppose you mean that the top is loaded (or stressed) with the downward force of the strings? I feel that is difficult to do with a mold fit because of the following 3 reasons. Firstly I use a protective film over the top, cause the last thing you want is to glue a bridge to your top. But I fear the protective film will break because of the high point loads between the highest points of the feet and the table. Secondly, even if the film does not break, you will deform the top (= the mold) at those highest points, so the shape you create will still not yield a constant surface pressure over the contact area. The low areas remain virtually un-loaded, because the viscous epoxy paste will continue to flow (viscously) away, just until all pressure is gone. So then it will not bear any load. It will do that even if it has a very high viscosity, only with a high viscosity it will take longer (that's the third reason). It is practically extremely difficult to time the setting (or gelling) point so that you end-up with an even pressure profile (unless that pressure is 0, so un-stressed). Maybe you could improve by doing it iteratively, starting off with an un-stressed fit and gradually increasing the load. Or re-work the un-stressed fit mechanically, if required.
Hi.
Can't speak on robobass's behalf, but my answer is yes.
I waxed the top, with beeswax IIRC. No problems.
Obviously I tried beforehand that the epoxy I was using didn't dissolve the wax
.
You lost me there.
My intention was to even out the differences (sloppy carver) between the bridge feet and the top under load, I wasn't worried or concerned about the necessity to decouple the bridge from the top with a thickness of epoxy.
In fact, I'd rather have as much wood to wood contact and let the epoxy just correct the sloppines.
IMO that's still a band-aid solution since carving the feet precisely isn't THAT difficult.
Thanks for posting, but why take a look?
Looks like someone hand-laid CF cloth on the face of a wooden bridge with clear epoxy and epoxied the sides black.
Looks nice, but probably doesn't do much. Aesthetics aside of course.
Now, if it was a hollow/foam core CF bridge, color me interested.
Regards
Sam
Can't speak on robobass's behalf, but my answer is yes.
I waxed the top, with beeswax IIRC. No problems.
Obviously I tried beforehand that the epoxy I was using didn't dissolve the wax
.You lost me there.
My intention was to even out the differences (sloppy carver
) between the bridge feet and the top under load, I wasn't worried or concerned about the necessity to decouple the bridge from the top with a thickness of epoxy.In fact, I'd rather have as much wood to wood contact and let the epoxy just correct the sloppines.
IMO that's still a band-aid solution since carving the feet precisely isn't THAT difficult.
Thanks for posting, but why take a look?
Looks like someone hand-laid CF cloth on the face of a wooden bridge with clear epoxy and epoxied the sides black.
Looks nice, but probably doesn't do much. Aesthetics aside of course.
Now, if it was a hollow/foam core CF bridge, color me interested.
Regards
Sam
Sorry to be clear, this was a bridge I had installed recently. It had a plastic frame, graphite core filling and a cf shell.
^Nailed it.
^Nailed it.
Hi.
Ok, that makes way more sense.
Did You make the bridge?
What's graphite core filling?
Divinycell?
Edit:Just did read Your PM, jumped the gun by asking did You make it.
Edit #2: That second pic is priceless.
Regards
Sam
Ok, that makes way more sense.
Did You make the bridge?
What's graphite core filling?
Divinycell?
Edit:Just did read Your PM, jumped the gun by asking did You make it
.Edit #2: That second pic is priceless.
Regards
Sam
