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A word of warning about brass hinges...

Last night i was alone in my work room / studio minding my own business when i was suddenly startled by a very loud "twaaannngggg..." that really made me jump...first thing i thought was the old poltergeist was up to its old tricks again (they do exist, you know...) and wondered what else i was going to hear that night....

This morning i found the culprit - my early build "The Captain" had its strings all wrapped around the neck in a most bizarre fashion, and i realised the brass hinge they were anchored to at the tail had snapped through metal fatigue, this "antique" hinge i used only on this 4 string build, another on a 3 string build, i wondered what would have happened if i'd been playing the thing and all four strings had recoiled in my face - doesn't bear thinking about, though brass is soft and i guess can only take a certain amount of strain after a few months! I guess the loud twang noise was the strings, still connected to the remains of the hinge, hitting another guitar, though sounded really spooky ...

Others may have years of use with brass butterfly hinges but i will not be using them again in future... (-;

Brass butterfly hinge taking the strain....until !

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Permalink Reply by Clock The Wolf on November 19, 2011 at 9:58am

According to the Codex vel Spiritus Maleficium (Olaeus Cretorius, University of Darmstadt, @ 1510), "Thee dread spirits condemned to stride about thee earth, by thee everlasting mercy of Our Lord and Saviour, wax wroth on all that is of thee metal called brass, even unto thee point of becoming most unhinged. Make of this great and terrible knowledge as you will, oh my brothers..."

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Permalink Reply by Lonman on November 19, 2011 at 10:51am

That is interesting and first I have headr fo this happening. Could you show us a pic of the broken hinge. I am not clear what part came apart. Thanks for sharing.

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Permalink Reply by Ron "Oily" Sprague on November 19, 2011 at 9:17pm

The new all-acoustic CBG album by Slowpaw Steve and The Captains of Industry:

Unhinged

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Permalink Reply by Slowpaw Steve T on November 19, 2011 at 10:14pm

snapped off, can't find the other bit gone in the rubbish...

(-: lol..!

Oily "Strat-O'-Nine-Tales" Fool said:

The new all-acoustic CBG album by Slowpaw Steve and The Captains of Industry:

Unhinged

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Permalink Reply by Roadkill a.k.a. John Maw on November 19, 2011 at 11:07pm

I think I know what the problem is. You were using four strings in what is clearly designed as a three string hinge. A clear case of misuse, whoever she is.

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Permalink Reply by Ron "Oily" Sprague on November 20, 2011 at 1:31am

That's funny. I was just getting ready to say that it was because this was a left hander's guitar, the hinge was upside down, and therefore all the curls in the hinge end pulled out from the string tension. >;-E

Roadkill a.k.a. John Maw said:

I think I know what the problem is. You were using four strings in what is clearly designed as a three string hinge. A clear case of misuse, whoever she is.

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Permalink Reply by Dan Sleep on November 20, 2011 at 1:46am

Since most hinges just have a tab of metal that is bent into a circular shape to wrap around the pin, I would guess that the total string tension just pulled the circular shape back open again. If it is a 4 string model, you very likely have over 100 pounds of total string tension when it is tuned up to pitch.

It would be as if you attached the same hinge to a piece of lumber and tried to suspend a 100 pound weight from it. Brass being a somewhat soft metal, it just wasn't up to the task.

Like you said, good thing it happened when it did instead of when you were playing it.

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Permalink Reply by Mark on November 20, 2011 at 2:11am

Hmmm, first time I've heard of this sort of thing happen with a hinge. Nevertheless it's a useful warning. I think the problem was obviously that the hinge in question was just not substantial enough for the load you put on it. I'm sure hinges are fine if they're not overloaded. Unfortunately these things aren't sold with a load rating printed on the pack because they're not intended for our uses. So you just have to judge by eye what sort of load they'll take. And if in doubt then over-engineer.

I guess this should be put down as a learning experience. Thanks for sharing the knowledge.

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Permalink Reply by Ron "Oily" Sprague on November 20, 2011 at 3:32am

But in true CBN Super Advanced over-thinking mode, this interesting bit o' math is submitted for your perusal:

http://www.ganter-griff.net/web/Querverweise/EN%5Cbelscha.pdf

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Permalink Reply by Dan Sleep on November 20, 2011 at 3:54am

Great information. I review it, and here is what I took away from it:

Blah blah, blahbity blah Blah blah, blahbity blah Blah blah, blahbity blah Blah blah, blahbity blah

Oily "Strat-O'-Nine-Tales" Fool said:

But in true CBN Super Advanced over-thinking mode, this interesting bit o' math is submitted for your perusal:

http://www.ganter-griff.net/web/Querverweise/EN%5Cbelscha.pdf

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Permalink Reply by Ron "Oily" Sprague on November 20, 2011 at 4:19am

Dan,

But of course! That is what CBN Super Advanced over-thinking mode leads to:

The Blahs.

However, should anyone actually wish to calculate the hinge load, as proxied by string tension, it CAN be done.

Then one can go to a variety of websites, with which I will not bore you, and select the proper hinge type. Just for those who don't mind being blah'd, it is of minuscule interest to note that the load from a 4-string guitar will indeed be slightly larger than 100 lbs - which means that the appropriate hinge size is something akin to what is used to hold up a building fire door. Those are pretty massive!

But what you SHOULD take away from this aspect of the discussion is:

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Permalink Reply by Slowpaw Steve T on November 20, 2011 at 4:29am

Found the other piece of the hinge! Comments appreciated folks, indeed a clear case of hinge misuse....amazing how much pulling power those slinkies have!!