Thinning a round violin bow


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If you are convinced this is needful .I would use a flexible vixen file, fine tooth (with the grain, not cross grain) ..With care, the octagon will come right up

The first four flats should be at 90 degrees and proceed from there

 

Good luck

 

Jim 

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By the time a new bow is fairly round, you should be close enough to get by with sand paper.  You're right that it is ridiculous to take off large amounts of wood with sandpaper.

 

It's unclear to me if you are talking about making a new bow, or trying to re-work a finished one.  Unless the bow in question is just junk, or you made it, I agree you shouldn't mess with it.

 

Maybe you should tell us a little more about your situation. 

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the only reason that I can come up with is - using a spring scale (grams) - pull the arch back to straight and getting a reading of over 1300 grams . there may be a case ... If it is under 600 grams I don't see much chance of success for a playing bow, as the stiffness (spine) will be way off

 

  In any event,  Its to light for a shovel handle

 

Jim

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Jim, where did you come up with the 600 and 1300 g figures?  Sort of make sense to me.

 

As to thinning, I have adjusted a few old cheap sticks with nice wood by first taking to normal non-lumpy bow specs.  Getting out the lumps.  Scraper, good light, compare to reference edges, feel a bunch, be careful.  That's the most I've needed to do, but were I going further, I would do small flats at 90 degrees, then again moved 45 degrees, and then in between, just to very slightly and evenly reduce.  Then sand to round carefully.  I have a hard time imagining wanting to do more than one tiny cut on a clubby stick with good wood.  Seems more cost effective to just get another stick.

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Steve

those are not from my work 

Another bow maker has tested many bows, as a bow maker, and has found that most bows good (or not so good) fall in the 600 to 1000 gram range and this was offered to me as advice (for which I am indebted) The normal sequence is to make the octagon, then go to round , and that transition to round will drop the defection by some 100 to 200 grams

 

I assume the transition back will be somewhat similar   kyklops is no rank beginner, having made some bows, and also is a competent player, seemingly  on a rational track (and obviously has not been trained to think only one way) 

 

He has asked for advice, hence, my use of a vixen file which tends to not leave humps and bumps, and is really a gang scraper, was my best thought   I like scrapers and not crazy about sand paper

 

If he is going to attempt this there isn't much room for error

 

Jim

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Makes sense - I have tested the other way, measuring deflection, must calibrate with this way, see how things relate.

 

I can see making round to octagon.  That seems a good deal of wood.  Round to round shouldn't be too difficult, but round to octagon would be fun.

 

I haven't used a Vixen style file.  I have seen them in use on metal, very aggressive and powerful.  I am more a scraper person, but now am curious about one of those Vixens on arching and anything else that needs shaving down.  Thanks for mentioning and explaining.

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The vixen that I use is an auto body file that is normally fastened in a holder   they are quite expensive ~40 to 80 dollars and works on metal like a plane works on wood - as aggressive goes - it depends on how it is used ... I would not use one on spruce or maple

 

High density resinous wood , just another good tool

 

Jim

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