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Midi Music Box Make
braeden-young Posted: 4 Apr 2023, 07:57 PM
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Joined: 19-February 21
Hey folks, made a midi music box based off Mitxela. Went through a good few iterations on the pins initially attempting to with 2mm brass.

Used an Arduino Mega, the sketch is still pretty basic.

The box is a bit crunchy still, might remake in the future. Getting some decent music though it seems a bit out of tune.

Instagram : https://www.instagram.com/p/CoyXJ2nPbuU/
Imginn : https://imginn.org/p/CoyXJ2nPbuU/


Full build album : https://photos.app.goo.gl/vy5Y4GoyKvGtJZkDA

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mit Posted: 4 Apr 2023, 09:42 PM
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yeah whatever

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Marvellous!!

The 3D-printed fingers seem to work well. Did you have any trouble getting them to the exact thickness? I know someone else tried 3D printing those parts and had to do a lot of sanding to get everything to work smoothly.

The toothed belt is a good idea. When I replaced my direct-drive servo with a belt drive I just used an O-ring, but it's quite sensitive to the tension on it, and slips easily. A toothed belt hopefully solves that problem. I did previously have a look for tiny toothed belts, which definitely exist since I've pulled some fine ones out of old printers and scanners, but all of them were too long and I wasn't sure how to shorten one. And all the new toothed belts I could find were (I thought) too wide to be practical. The one you're using seems to be fine though.

Weird that it went out of tune. I wonder if that was just some damage that happened while you were building it.

Are the brass rods thicker than the ones I used? Did you have trouble fitting them to the servo arms?

Have you tried fitting a contact mic to it?

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braeden-young Posted: 11 Apr 2023, 05:32 PM
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Thank you!

I had about 6 iterations getting the fingers right. A slight bit of wiggle room so not too much friction, no need to sand, and still accurate enough to hit to the notes consistently.

Threw it up on Thingiverse : https://www.thingiverse.com/thing:5964611

The toothed timing belt I had from a previous project making a hanging drawing plotter, but my attempts to splicing the length to make a belt was far too stiff. I ended up just buying a set aimed at 3d printers. Seems to work well.

My first attempt was using 2mm brass rod - thinking I'd avoid the soldering process... Whelp that ended up rubbing too much, pressing against all proceeding servos. I went with 1mm, and stacked them soldering at a few points down the length. Rigid enough, but still flexible for the cases where a note will fire prior to the pin completely reseting. I originally had to drill out the servo arms for the 2mm stock, the 1 mm fit fine in the preexisting holes.

A contact mic seems like a must. The box resonates well, and the lid dampens the servo noise, but still far too quiet. I may try to remake the box and incorporate an acoustic horn into the base.

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