Violin bow flexibility
Is it helpful to know a bow's flexibility and/or stiffness? Is there any type of measurement that is made for comparison purposes? Would wood bows be more flexible than carbon fiber ones?
You can balance the flexibility or stiffness of the stick to some extent by the amount of hair used to rehair the bow.
You might be able to get an idea of the stiffness/flexibility of a stick if you know its weight, thickness, and density. You can tell most easily by playing.
Andrew-- less hair for flexible bows? How much did you find yourself changing the amounts?
Stephen, if you send me your email address I can send you the spreadsheet with everything I did back then (20+ bows).
Thanks. I am at stephen[dot]symchych[at]sant[dot]ox[dot]ac[dot]uk
Unless the stick is way too hard or way too soft, I don't think the player has any business fretting about the stiffness of the bow stick. You'll feel it if it isn't right, anyway---I played on a cruddy German factory bow for a while that could be pulled totally straight with the absolute minimum of force. I hate that bow! Using it feels like trying to hammer a nail with a pillow.
I'm finding that there are a few borderline cases. Many 19c sticks, whether because they were designed that way, or because they have too many miles on them, are much softer than what is considered normal now. If rehairing correctly can get more use out of them, that is all to the good. And even with bows of a more conventional spec, it doesn't follow that the same wad of hair will do equally well for all.
All (maybe almost) the bows I worked with had a range of hair diameters so any numbers I came up with and worked with were averages over the "hank" of hair.
Stephen, it's my understanding that some 19th C bows were designed that way. You might notice in my EXCEL "bow calculator" the first two bows (F.N. Voirin and R. Weichold) are both 19th C bows one soft (63n/m) and one stiff (90n/m). but the 20th C (~1950) Holzapfel bow that we bought new in 1952 is also soft (63n/m) - by design. It is my understanding that Tourte made soft bows too.
It's not uncommon for bow makers to measure deflection when making a bow, comparing bows, or evaluating a bow. A 1lb weight is used for violin/viola bows, which is hung in the middle of the stick and the deflection is measured in thousandths of an inch. Violin bows fall between 160 - 220. Scroll down to the bottom of my article on bow making tools to see the deflection jig I use: https://adbowsllc.com/2018/10/21/bowmaking-tools/
JUST SAW THIS:
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