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Problem Of My Carbon Fiber Bow


Fellow

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Hi all,

I don't want to create a disturb of my question. After bought a (not so cheap $400) carbon fiber

bow for 4 years, I realize a problem that won't exist on a wooden bow.

The problem is that the hair tension is too great (for CF bows). So the turning screw is hard to

turn and the slick (free movement) is narrow. Unless the rehair luthier is very good, to set the

bow hair just the right length (hair length) your CF bow is in trouble. where you find such a bow

re-hair luthier?

PS. I brought the bow back to my luthier who re-haired it a year ago. He said the weather

causes it. (shrunk)

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Yuen,

The problems you describe are not limited to carbon fiber bows. Wood bows can develop the same problems. Hair can shrink if humidity gets very low. It's not uncommon to rehair a bow (wood or carbon fiber) for no other reason than the hair length is no longer satisfactory; it's gotten either too long or too short.

Any good rehairer can give you exactly the hair length (within a mm or so) your bow requires, and that rehairer can also estimate what might happen to the hair length in the near future, according to the climate you live in, and accommodate the likely changes in hair length in the rehairing.

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True, but I rehaired two bows at the same time,($50 each, total $100) one wooden bow and one CF bow. The wooden bow still works perfectly, the CF has this problem. Both are expensive bows ($1000 vs $400).

It seems the only solution is to rehair the CF bow. The question is now " shuld I ?"

I am not to blame on CF bow (in general) It is my conomic question more than anything else.

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Yuen,

If I understand what's going on, you seem to prefer a bow that has the following two qualities:

1. The stick is fairly supple and flexible, and not stiff.

2. The hair, when tightened to your preferred tension, is removed quite a ways from the stick. That is, there is a fairly large gap (measuring at the lowest point of the stick's camber) between the hair and the stick when the bow is tightened.

A normal rehairing, regardless of length of hair (and we're talking about a difference of a few mm between a snug rehairing and loose one) will not change a stiff stick into a flexible one and will not increase the distance between hair and stick, when hair is at playing tension.

You can try asking for a loose rehairing. An extra 3 or 4 mm in hair length (compared to a snug rehairing) might make the bow at full tension feel a bit spongier because of the extra length, but I doubt you'll really get the results you want.

You can also try asking for a heavy rehair, more hair than usual. That will allow you to crank the bow hair tighter and move it away from the stick. You'll still have a stiff stick, though, and it may feel even stiffer for the extra tension.

An abnormally long or short rehairing may not work because (if too short) frog eyelet won't fit into stick slot, or (if too long) the frog can't be cranked back far enough to get enough tension into the hair.

If you really don't like the hair tension you get with your CF bow, then you probably want a different bow.

Not all CF bows are stiff. Many are, but I have one in the $300 range that really isn't stiff enough for my tastes. So, if you want to buy a CF bow, order 3 or 4 of them for trial. Even in the same brand and type, they will indeed vary in stiffness and weight.

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quote:


Originally posted by:
yuen

True, but I rehaired two bows at the same time,($50 each, total $100) one wooden bow and one CF bow. The wooden bow still works perfectly, the CF has this problem. Both are expensive bows ($1000 vs $400).

It seems the only solution is to rehair the CF bow. The question is now " should I ?"

I am not to blame on CF bow (in general) It is my economic question more than anything else.

I would say if the bow is still adjustable through the range of tension you need for playing, and the only problem is that the hair doesn't go fully slack when you loosen it fully, don't worry about it! As you noted earlier, it won't hurt the stick to remain under partial tension since carbon fiber doesn't lose camber like wood would. (My opinion only, but confirmed on the Arcus website for their bows.) -Steve

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A really stiff bow needs more hair than does a softer stick. Some rehairers know this, but some (who otherwise do a fine job) don't. They all should know this and abandon "atandard hanks of hair with precounted amounts of hair.

I did some "tests" back before 9/11/01 of a number of bows and came up with (what i think) is a relationship between the stiffness of a bow stick and the appropriate number of hairs.

If you go to http://members.aol.com/bowedstrings/ and select the "bow calculator.xls" you will see the relationships.

As far as I can tell, the problem seems to be that there are several parameters to be optimiized:

1- the tension (and actual stretch (or "strain")) in the individual hairs touching the strings

2. the total tension of all the hairs on the stick

3. the amount of camber (or curvature) left in the stick (to optimize its playing qualities) when the hair is optimally tightened for playing.

Andy

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It is interesting to realize that CF bows are different from wooden bows. I wonder a CF bow

camber of a carbon fiber bow never changes any way . The luthier seemed to know that he just

made it so tight once for all. If it is the rght tension, then it is the right tension.

The weather causes it too tight, not the luthier. Interesting situation. Something to learn.

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Yuen,

The next time you get your CF bow rehaired, let the rehairer know what problems you had with it and what preferences you have. I am sure he can accommodate you.

CF bows (all the ones I know) are rehaired just like wood bows. So there's nothing about a CF bow that will force a rehairer to do the job differently for a CF bow than he would for a wood bow.

However, because most people like snug rehairings (the hair as short as possible), the rehairer might be inclined to rehair a CF bow a bit shorter than a wood bow because, with the CF bow, there is little or no danger in losing camber and in having the eyelet gouge the front end of the bow stick slot, if the hair starts to shorten after the rehairing.

If you don't like snug rehairings, let the rehairer know that.

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