Magic Coin Piercing Trick

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Published on June 11, 2012
This thing was Featured on June 11, 2012

Description

Abracadabra! Perform a magic coin piercing trick and amaze your family and friends. The eight solid pins pierce the solid coin eight times yet the coin comes back out of the container undamaged!

See the demo video at youtu.be/96b9ElucVW0 .

This project is sure to amaze your kids and help reassure your spouse that the 3D printer is a true household asset!

Also see Thing 25344, thingiverse.com/thing:25344.

Enjoy!

11 June 2012: Add missing OpenSCAD source file
11 June 2012: Ran the bottom piece through Netfabb
14 June 2012: Determined cause of problems for Slic3r; uploaded new top & bottom .stl file and new .scad file

Instructions

Download the three .stl files, slice them, and print them. For maximum impact, print the coin and pins a contrasting color from that used for the top and bottom of the enclosure. Note that I sliced using 100% fill and 4 shells. The pins may print better with a raft.

You can use the supplied OpenSCAD file to regenerate the container and pins to your specifications. For example, to a size which will work with your local currency.

To perform the trick,

1. Let your audience inspect the coin and pins. Check your sleeves, etc., etc.
2. Place the coin into the bottom of the container.
3. Place the top cover over the bottom. The two pieces have alignment tabs to ensure correct orientation of the pin holes between the top and bottom.
4. Begin by "piercing" the coin with a pin through one of the outermost four holes. Do NOT start with any of the four inner holes. By using one of the outer holes, the coin is tipped upwards and out of the way of the pins.
5. Place the remaining seven pins through the remaining seven holes.
6. Show your audience that the pins move: push one from the bottom and see the pin's head rise.
7. Remove the pins. Unlike in the video, things will be a little quieter if you remove the outer pins first: that way the coin only shifts down a little at a time. If you make the last pin an outer pin, then the coin will have farther to drop.
8. Give a gentle magic "tap" and/or shake, maybe saying "presto" or "abracadabra" at the same time. This is really to make sure that the coin has dropped back down.
9. Re-open the container, showing the audience that the coin is still there and undamaged with no holes.
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Very nice, I printed one. If I may suggest something, the cirrcles inside the bottom part are very thin, you should make them thicker.

right now they are 1 wall width with a .35 mm print head.

This is BRILLIANT! Yet to post an "I made one" picture as it has only just come off my RepRapPro Huxley and been demonstrated to my family! For us UK folk - try a "magic" 50p piece - just about the right size although it would be better if the 50p didn't have so many corners. Had some problems with the SCAD file not producing a Slic3R capable STL files so ended up using the STLs provided. (I wanted to print top and bottom on the same print run but printed all parts separately.

Thanks for the kind words.

BTW, determined the cause of the non-manifold mesh. (RepG/Skeinforge was fine with it; appears that Slic3r was not.) The pin holes in the bottom piece were sufficiently close to the support rings that something was going awry with the facets which OpenSCAD was outputting. I moved the pin holes
an addition 0.05 mm away from the rings and all is now happy according to Netfabb.

I uploaded new top
&
amp; bottom .stl files as well as an updated .scad file.

Slic3r complains the bottom STL isn't manifold... Netfabb Cloud fixed it, but there's still some funky looking lines...

Thanks for noting this. I generally depend upon OpenSCAD itself to warn me when things aren't manifold. I both ran the bottom through Netfabb and uploaded that as well as adding the OpenSCAD source file which somehow wasn't uploaded. (My mistake, I assume.)

Dan

One of the first magic tricks I learned to do. Defineatly going to print this thing.

Perfect for people who don't live anywhere near a dollar store.