I made this project in about two hours. It is a mini volt meter from Adafruit in a 3D printed case in the shape of a grenade with banana jacks for connecting test leads or probes. It can be used to test batteries or circuits in electronics projects. It can read voltages from 3V to 30V DC.

I printed the two halfs of the grenade on my Makerbot Cupcake CNC. I got the 3d design file from Thingiverse. It’s “Hand Grenade” by Hairygael (Which is a derivative of “Hand Grenade” by MNinventer)

Bill of Materials

Mini Voltage Meter: $7.95 + shipping, from Adafruit
Banana Jacks: $6.19 + tax, from Frys Electronics
Olive Green 3mm ABS plastic: $17.75 + shipping (Only used less than about $0.50 worth), from 3dprinterstuff.com

Here is my response:

I really like the technical challenge of this project. I personally don’t have a need for a perler bead “printer” but it’s an awesome concept, challenge and project.

I really like the gate idea or a variation on it. Such as the “looking ahead” idea, but look ahead let’s say four or five beads and planning the course based on that. It would take more processing power to plan that far ahead. A propeller probably could handle that.

I’m not sure what part of the 3D-printed disc is tapered. Could you please explain that a little better?

I agree with keeping it simple. I now realize that my idea would cost more in 3D printing time and cost more for multiple motors and bearings. Using servos and a radial coordinate system saves a lot of money. No need for precision rods, timing belts, stepper motors or pulleys. Using what bead you get and then choosing the closest place to put it seems much more efficient than I had assumed(incorrectly) from the description, “…to direct it toward the build surface or to a discard pile.”

“Or we could run the sorting and placing tasks concurrently, with the placing task waiting on more beads when it runs out of a particular color.” If you could combine that with a method to move on to the next color and then come back to the color with the low number of beads when there is a sufficient amount in the hopper it may be even more efficient.

I think I might try a variation on my idea, just for sorting, maybe with skittles or m&ms. It seems like it’d be a fun project.

I’ve learned a lot from your post(Scanlime), for my own projects:

1) I need to figure out and decide what my goals and requirements are for projects before I start them.

2) There are many more ways than one to solve a problem. I need to think of all the possibilities first and not dismiss them so quickly.

3) I need to think more outside the box.

4) I should try to think of the extremes and not only within the limitations I see.

P.s. I realized that a lot of the really awesome projects I have seen on Hack a Day and Makezine blog have been made by you, Scanlime. Thank you for the awesome things you do and make!

Then I saw this photo( http://www.flickr.com/photos/micahdowty/5444740676/ ) and the description. “On the left, a sorting disc I’m testing. It mounts directly to a micro servo (press-fit onto the spline gear). It has a circular hole that can hold one bead while the robot examines its color, then at the proper time it can shuffle the bead off to one side or the other, to direct it toward the build surface or to a discard pile.” What bothered me was the, “…to direct it toward the build surface or to a discard pile.”” part. It seemes like an inefficient method to get the color you need.

I’ve posted my 3D layout files to Thingiverse:
http://www.thingiverse.com/thing:6468

So I was watching Weekend Projects a about two and a half months ago and saw how to make a 3 by 3 by 3 LED cube. I thought, “Hey! I could do that with my Arduino!” and I did. Basically, I can turn any individual LED on or off.

I started with soldering together the LEDs in layers of nine. Then I played around with how to wire up a protoboard with two Shift Registers on it and the LEDs to make a Shield for the Arduino. The first try was messy. The second try was better but not ideal. The final wiring guide may LOOK messy, but it’s basically what I used.

The final wiring on the protoboard from the bottom is the last photo.

The software was a compilation of the original software from the Weekend Projects post and the ShiftOut example on Arduino.cc. I started with the “Code Sample 2.3 – Dual Defined Arrays” at the bottom of the ShiftOut example and slowly stirred in the original code to produce the final result. Here is the final code.

Here’s a link to the Flickr photos.

P.s. On a side note, I did the layout and wiring wrong so I had to modify the code to compensate for the LEDs being connected wrong.