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Josh Henry

Broken bow screws

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I had something happen to me this week that has never happened before—I was tightening up a bow to apply rosin on it after a rehair, and the screw broke. It broke in half at the eyelet, such that the frog became stuck, and wouldn't move forward or backward. At that particular moment, the spirit of cuss entered my shop…<_< I was able to free it and replace the screw before the owner arrived (yes, I did tell them what happened), but I've never had a screw break on me before. The bow was a nice, fairly new German handmade bow that I had rehaired several times in the past, and there was no significant wear on either the screw or eyelet.

Additionally, over the last several weeks, I have had 4 other bows in my shop to repair this very same damage. They all had broken screws at the eyelet. This is usually an occasional repair in my shop (maybe 6 times a year), but I've never seen such a flow of broken screws concentrated into such a short time period. On all of the bows, there was no particular reason (like crooked screwholes) to merit a broken screw.

My question is this—Could the breaking of screws be due to the cold weather/low humidity season that we are in? I know metal get brittle in extreme cold, but we're talking about bows that are used by professional players, and treated with the same care as their instruments. Is the breaking of screws coincidence or cold-weather related?

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Sounds like a very wild coincidence, sabotage, or (more probably) a manufacturing defect.

Have you noticed any pattern of failures by bow maker names and/or screw manufacturing styles?

If you still have any of the broken screws, it might be well to have a local metallurgist look at them under magnification and make hardness tests.

There has to be a cause but it will take some detective work to find it. Anyone on MN who has had this problem should save the evidence and inform you.

Good Luck Josh!

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Low numbers like 4 or 6, compared to the number of bows you see, could simply be a statistical fluctuation. If you note a seasonal/temperature pattern over a few years, that would be a stronger indication.

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Sounds like a very wild coincidence....

I don't see how it could be anything else. I have rehaired or worked on thousands of bows over 20 years, and I have never had a screw break on me or had anyone bring me a bow with a broken screw. If it were temperature or humidity related, it would happen every year at this time, just like the hair always shortens in the winter in New England.

Don't tell any environmentalists about this. They will call it more evidence of global warming or, even worse, climate change.

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Sounds like a very wild coincidence, sabotage, or (more probably) a manufacturing defect.

Have you noticed any pattern of failures by bow maker names and/or screw manufacturing styles?

If you still have any of the broken screws, it might be well to have a local metallurgist look at them under magnification and make hardness tests.

There has to be a cause but it will take some detective work to find it. Anyone on MN who has had this problem should save the evidence and inform you.

Good Luck Josh!

I do agree that it is probably a wild coincidence. There was no correlation at all between the bows--a couple cello bows, several violin. One circa 1880 old French bow, one Chinese bow, several newish German bows. All of them were iron screws, although one looked like it could have been stainless steel. I've haired a couple of them before, the others--first time in the shop. I don't think it likely that there would be any manufacturing defect that would be consistent with the variation of age and origin. I've just never such a rash of broken screws before.

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I do agree that it is probably a wild coincidence. There was no correlation at all between the bows--a couple cello bows, several violin. One circa 1880 old French bow, one Chinese bow, several newish German bows. All of them were iron screws, although one looked like it could have been stainless steel. I've haired a couple of them before, the others--first time in the shop. I don't think it likely that there would be any manufacturing defect that would be consistent with the variation of age and origin. I've just never such a rash of broken screws before.

COuld it be a matter of lack of lubrication on the screw or eyelet?

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COuld it be a matter of lack of lubrication on the screw or eyelet?

Lack of lubrication would most likely cause the eyelet threads to become worn and stripped, or possibly the same for the screw threads, but I can't see how it could cause the screw to break.

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Perhaps the the eyelets had been adjusted with the screw? I see a lot of those tell tale marks on frog linings, sometimes from the factory, that show someone adjusted the depth of the eyelet by turning it with the screw. I saw a nice frog that had an upper corner broken off because the player adjusted the eyelet in that manner. John Norwood Lee gave me an eyelet adjuster, a simple, convenient tool for safely adjusting the eyelet.

Back to your problem of the broken screws, that's the only thing I could think of that might stress the screw at that specific point to induce a fracture. I doubt lack of humidity could cause that problem. At my shop I've seen three broken bridges come in within a weeks time, presumably from being exposed to overly dry air. Yup, winter is here...

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Perhaps the the eyelets had been adjusted with the screw?.... that's the only thing I could think of that might stress the screw at that specific point to induce a fracture....

Not a chance.

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I believe metal can become brittle in cold weather.I went into my workshop today ,was 14F last night and picked up my plane to straight a cello neck block .Adjusted the blade depth and the `y` shaped piece broke in half with hardly any pressure.

On a slightly different note just had an earthquake in Northern England !! The whole ceiling shook ,i thought a bomb had gone off somewhere. :o

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Hi,

How do you remove the broken part from the button ? Is there a particular way to do it ? I mainly do rehairs in addition violin repairs, but I have not learnt this so far...

Thanks for your tips.

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Are these all bows you have worked on previously?

If so, perhaps whatever you are using for lubricating the threads is breaking down or seizing up in the threads.

I've always just used a quick swipe of bee wax on the threads, rather than messy grease.

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I don't see how it could be anything else. I have rehaired or worked on thousands of bows over 20 years, and I have never had a screw break on me or had anyone bring me a bow with a broken screw. If it were temperature or humidity related, it would happen every year at this time, just like the hair always shortens in the winter in New England.

Don't tell any environmentalists about this. They will call it more evidence of global warming or, even worse, climate change.

But this is evidence.

Shattering metal will create heat.

This heat is cumulative.

Slowly, over millennia, as billions of bow screws add to the effect - the atmosphere warms and the polar caps melt.

Earth becomes a veritable hot box unfit for human habitation.

Thanks, Brad, for ruining the planet for everyone.

My immediate supposition would also be manufacturing error first, wild coincidence second (but still very possible).

Were the bow screws alike, or possibly from the same lot or manufacturer?

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But this is evidence.

Shattering metal will create heat.

This heat is cumulative.

Slowly, over millennia, as billions of bow screws add to the effect - the atmosphere warms and the polar caps melt.

Earth becomes a veritable hot box unfit for human habitation.

Not to mention the heat generated by the friction of the threads as the screw turns in the eyelet.

This is devastating! I'm going to remove all those screws, destroy them and retrofit cremailleres. We must all be diligent in saving the planet!

Al Gore may even give me a commendation!

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Not to mention the heat generated by the friction of the threads as the screw turns in the eyelet.

This is devastating! I'm going to remove all those screws, destroy them and retrofit cremailleres. We must all be diligent in saving the planet!

Al Gore may even give me a commendation!

This is true green thinking - I see a Noble Prize in the future, or, perhaps the queen will knight you!

Sir Bill.

It has a nice ring to it...

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I'm not going to just stop there. A significant amount of heat is generated by the friction of the hair against the strings. I shouldn't divulge too much before the patents are applied for, but I'm going to develop a frictionless rosin to combat global warming. As a happy byproduct, this rosin will also make even the most raw beginner sound better.

Sorry Josh,

I couldn't help myself.

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I'm not going to just stop there. A significant amount of heat is generated by the friction of the hair against the strings. I shouldn't divulge too much before the patents are applied for, but I'm going to develop a frictionless rosin to combat global warming. As a happy byproduct, this rosin will also make even the most raw beginner sound better.

Sorry Josh,

I couldn't help myself.

Already done, have you ever heard of the "ebow" for guitars. We'll just have to get the players to adapt....right :P

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I think the heat created by bow friction is a good thing for the planet ... instead of having an electric heater in the room we could just get someone to play the violin. We might need a small ensemble on genuinely cold days but that way we could be subsidizing the arts while also caring for the environment.

Killing two birds with one stone.

Sorry, bad choice of homily, no-one should be killing any birds, forget I said that ....

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Lots of solar flares recently. I'd attribute the breakage to the metal becoming brittle due to increased radiation levels.

Of course, there's always the possibility, however slim, of a local anomaly of some sort. My Dad had a bottle that contained a sand picture, which he agitated until the pattern was degraded. Whenever it began to reassemble itself into its old form, he would take precautions. (Of course, he had to shake the bottle to see if it would regenerate a pattern. These things do not move on their own, you understand).

The OP might be well advised to rotate his bow stock 90 degrees; change in magnetic flux lines will alter the flow of charged particles, and should result in less embrittlement.

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I think the heat created by bow friction is a good thing for the planet ... instead of having an electric heater in the room we could just get someone to play the violin. We might need a small ensemble on genuinely cold days but that way we could be subsidizing the arts while also caring for the environment.

Killing two birds with one stone.

Sorry, bad choice of homily, no-one should be killing any birds, forget I said that ....

How much bowing energy would it take to cook two birds, say Cornish Game Hen size?

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How much bowing energy would it take to cook two birds, say Cornish Game Hen size?

In BTU's?

(Bowing thermal units)

Oh, I'd say, somewhere in the neighborhood of 1 - 1.5 Beethoven's violin Concerto in D (The Pearlman one...)

Sorry, Josh, once I get started, I don't generally know when to stop...

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In BTU's?

(Bowing thermal units)

Oh, I'd say, somewhere in the neighborhood of 1 - 1.5 Beethoven's violin Concerto in D (The Pearlman one...)

Sorry, Josh, once I get started, I don't generally know when to stop...

There seems to be enough hot air at the moment. :D:P

It’s OK, I’m a hot air expert. ;)

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I don't know what a Cornish Game Hen is exactly, but I think 2 pheasants would require about 2 hours 30 minutes of "Flight of the Bumble Bee". CT is vastly underestimating the BTUs required - you have to remember that in any concerto the violinist stops playing a lot of the time. This makes for inefficient cooking and also increases the risk of salmonella.

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