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I have a client who wants me to build him a collapsing acoustic guitar for a gag in his show. The real problem is that it needs to reset so he can do it all over again in subsequent shows. I've thought about doing kind of a faux Spanish heel and cutting slots in the neck and tail blocks for the sides to slide into. I could use magnets embedded in the top of the slot and in the side to keep things in place. I could use the same magnet premise to attach the top and back (embed magnets in the linings).

Obviously there won't be any string tension on it at all. It needs to be loose enough so that it crumbles when he attempts to strum the first chord, but it needs to be solid enough that it doesn't fall apart while he's handling it.

Any ideas?

Strong magnets

http://www.soss.com

Invisible hinges

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My memory is so good, sometimes I remember things that never happened.

K & J Magnetics has great prices on small surplus neodymium magnets (as well as lots of fair priced non-surplus magnets). Use them in pairs. lots of people use them in model airplanes, for example you cut little recesses into the wood of the wing mount and glue three or four tiny magnets in the recesses with superglue. Then you stick magnets onto those magnets. Carefully, using a toothpick and magnifiers, put a tiny drop of superglue on each second magnet. position the wing on the magnets and hold motionless untill the glue cures. The wing is held on by the magnets but pops off without breaking in a crash, and snaps right back on in an instant. If the hold is not strong enough, just add more magnet pairs.

Rubber bands

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Keeping with the magnet theme, you could have small magnets in one side of each joint and have them attach to the iron of corresponding small battery powered electromagnets (you could probably make these to fit using some small inductors and some iron slugs). Maybe one in the tail block and one in the heel block (or two if you want the neck to come off. The permanent magnets hold it all together by their attraction to the slugs in the electromagnets but are oriented such that when the switch is turned on (during the strumming motion) they are repelled by the matching polarity of the electromagnet. The whole structure could explode all at once.

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

Thanks for the input, everyone. Bryan, the idea of electromagnets sounds like a perfect solution. I'll to some toying around with that to see what I can come up with.

Thanks again, all!

I'm not sure exactly what the schtick is here but I'll add what I think would be funny. . . I picture the sides staying attached to the heel block and neck but they are in tension when closed at the tail block. When the gag goes off, the sides release from the tail block and spring open wide (still attached to the neck), the back drops off all together and the top falls only connected by the strings. The player is left holding a neck with wishbone looking sides splayed out and the top hanging from his left hand in playing position. I'm chuckling just thinking about it.

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.