Adding Recycling Codes To 3D Prints

Every little plastic bauble you interact with has some sort of recycling code on it somewhere. Now that we’re producing plastic 3D printed parts at home, it would be a good idea to agree on how to recycle all those parts, and [Joshua Pearce]’s lab at Michigan Tech has the answer; since we’re printing these objects, we can just print the recycling code right in the object.

The US system of plastic recycling codes is particularly ill-suited for identifying what kind of plastic the object in question is made of; there are only seven codes, while China’s system of plastic identification uses 140 identification codes. This system for labeling 3D printed parts borrows heavily from the Chinese system, assigning ABS as ‘9’, PLA as ’92’, and HIPS as ‘108’.

With agreed upon recycling codes, the only thing left to do is to label every print with the correct recycling code. That’s an easy task with a few OpenSCAD scripts – the paper shows off a wrench made out of HIPS labeled with the correct code, and an ABS drill bit handle sporting a number nine. 3D printing opens up a few interesting manufacturing techniques, and the research team shows this off with a PLA vase with a recycle code lithophane embedded in the first few layers.

Whiteboard Clock Draws the Time

[Maurice] recently built a clock that draws the time (Google Doc) on a white board. We’ve seen plenty of clock hacks in the past, and even a very similar one. It’s always fun to see the different creative solutions people can come up with to solve the same problem.

This device runs on a PIC16F1454 microcontroller. The code for the project is available on GitHub. The micro is also connected to a 433MHz receiver. This allows a PC to keep track of the time, instead of having to include a real-time clock in the circuit. The USB connector is only used for power. All of the mounting pieces were designed in OpenSCAD and printed on a 3D printer. Two servos control the drawing arms. A third servo can raise and lower the marker to the whiteboard. This also has the added benefit of being able to place the marker tip inside of an eraser head. That way the same two servos can also erase the writing.

The communication protocol for this systems is interesting. The transmitter shows up on [Maurice’s] PC as a modem. All he needs to do to update the time is “echo 12:00 > /dev/whiteboard”. In this case, the command is run by a cron job every 5 minutes. This makes it easy to tweak the rate at which the time updates on the whiteboard. All communication is done one-way. The drawing circuit will verify the checksum each time it receives a message. If the check fails, the circuit simply waits for another message. The computer transmits the message multiple times, just in case there is a problem during transmission.

Parametric Spherical Speakers Are Not A Moon

A good speaker enclosure is not just about building a box out of plywood and covering it with carpet, although playing with 1F capacitors is pretty cool. No, for a good speaker enclosure you need the right internal volume, the right size bass port, the right speaker, and it should definitely, certainly, not be a moon.  [Rich] figured out he could do all of this with a 3D printer, resulting in the NOMOON: The NOMOON Orbital Music-Making Opensource, Openscad-generated Nihilator.

This work is a continuation of earlier work that designed parameterized speakers in the shape of Borg cubes. Now [Rich] is on to Borg scout ships,  and this version has everything you would expect for speaker design.

The NOMOON is available on the Thingiverse Customizer with variables for the internal diameter, the volume of the enclosure in liters, wall thickness, speaker hole, bass port, and wire holes. Of course a customized design is also possible with a stock OpenSCAD installation.

[Rich] has printed a few of these not moons and even with a speaker with terrible bass response, he has a pretty good-sounding setup as far as Youtube videos go. You can check that out below.

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Automated CAD Design for Enclosures

[Jon] a.k.a. [Pedantite] recently added small-scale laser cutting to his business and thought about using that laser cutter to add some value to some of the many project designs he creates. Yes, this means custom laser cut enclosures, but how to go about it? [Jon] loves automation, and that can only mean automated design of laser cut enclosures by reading the board files from his project library.

The idea of automating the design of plastic enclosures was to read the design files, figure out the dimensions of the board and where the mounting holes go, and generate a file for the laser cutter. The weapon of choice was OpenSCAD, a design language that can be highly parameterized, read external design files, and spit out proper DXF files for laser cutting.

[Jon] set up his toolchain as a Python script that reads design files, sends parameters off to a .SCAD file, and generates a DXF for the laser cutter. There’s also a bit that generates enough data for Blender to render a 3D image of the finished product, all only from gerbers, a drill file, and a few user variables.

The source for these files haven’t been released yet, but that’s only because it’s in a proof-of-concept stage right now. You can check out an example of a render of one of the cases below.

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Open-Source Water Quality Tester

Contaminated water is a huge problem in many third-world countries. Impure water leads to many serious health problems, especially in children. Installing a water purification system seems like a simple solution to this problem, but choosing the right purification system depends on the level of contaminants in the water.

Water turbidity testers are often used to measure the severity of water contamination. Unfortunately most commercial water turbidity testers are very expensive, so [Wijnen, Anzalone, and Pearce] set out to develop a much more affordable open-source tester. Their tester performs just as well as commercial units, but costs 7-15 times less.

The open-source water tester was designed in OpenSCAD and 3d printed. It houses an Arduino with a custom shield that measures the frequency from several TSL235R light-to-frequency converters. An LED illuminates the water and the sensors measure how much light is diffused and reflected off of particles in the water. Another sensor measures the brightness of the LED as a baseline reference. The turbidity of the water is calculated from the brightness values, and is displayed on a character LCD. More details about the tester are included in a fairly extensive paper.

[Thanks Andrew]

A 3D Printed Peristaltic Pump

After getting access to a Lulzbot 3D printer, [Tim] designed a 3D printable peristaltic pump. The design was done in OpenSCAD, which makes it parametric and easy to modify.

Peristaltic pumps work by squeezing a length of tubing to push fluids. This mechanism is similar to how your intestines work. The pump provides an isolated fluid path, which is why they’re commonly used in medical and food grade applications. Like many products in the medical space, these pumps tend to be rather expensive. Being able to print one for your own projects could save quite a bit of cost.

The pump is based on [emmett]’s gear bearing design. One nice thing about this design is that it is printed preassembled. Pop it out of the printer, add some tubing, and you’re ready to pump fluids.

On top of the isolated fluid path, this pump gives accurate volume measurement. For that reason, we can imagine it moving booze for a robotic bartender build. After the break, a video of the pump moving some fluid.

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The Rabbit H1 is a Stationary Mouse Replacement

rabbit h1

[Dave] has some big plans to build himself a 1980’s style computer. Most of the time, large-scale projects can be made easier by breaking them down into their smaller components. [Dave] decided to start his project by designing and constructing a custom controller for his future computer. He calls it the Rabbit H1.

[Dave] was inspired by the HOTAS throttle control system, which is commonly used in aviation. The basic idea behind HOTAS is that the pilot has a bunch of controls built right into the throttle stick. This way, the pilot doesn’t ever have to remove his hand from the throttle. [Dave] took this basic concept and ran with it.

He first designed a simple controller shape in OpenSCAD and printed it out on his 3D printer. He tested it out in his hand and realized that it didn’t feel quite right. The second try was more narrow at the top, resulting in a triangular shape. [Dave] then found the most comfortable position for his fingers and marked the piece with a marker. Finally, he measured out all of the markings and transferred them into OpenSCAD to perfect his design.

[Dave] had some fun with OpenSCAD, designing various hinges and plywood inlays for all of the buttons. Lucky for [Dave], both the 3D printer software as well as the CNC router software accept STL files. This meant that he was able to design both parts together in one program and use the output for both machines.

With the physical controller out of the way, it was time to work on the electronics. [Dave] bought a couple of joysticks from Adafruit, as well as a couple of push buttons. One of the joysticks controls the mouse cursor. The other joystick controls scrolling vertically and horizontally, and includes a push button for left-click. The two buttons are used for middle and right-click. All of these inputs are read by a Teensy Arduino. The Teensy is compact and easily capable of emulating a USB mouse, which makes it perfect for this job.

[Dave] has published his designs on Thingiverse if you would like to try to build one of these yourself.