This DLP 3D Printer Build Is Going Really Well

We suppose [Dan Beaven] got up one day and said, “I’ll make my own resin 3D printer, with resin management and an advanced separation mechanism!” It’s a build log that shows just how possible it is to roll your own resin printer.

Prints on a dime!
Prints on a dime!

The machine isn’t finished yet, but the example prints coming off it are already very impressive. [Dan] stopped the print midway to get this photo of the detail on the stairs in the standard rook torture test.

[Dan] wants a lot of features from his machine that some of the more polished commercial printers are only now offering. One really nice one is the sliding and twist separation instead of tilt. This will allow for cleaner separation between layers during a print, a lower failure rate, and also faster print times.

He also added resin management with a peristaltic pump. This reduces the size of the build vat, and less resin will be exposed to the elements and wasted. It also means that the printer can run unattended. In the resin handling area of the printer he’s also added a carbon air filter. This lets him run higher performing resins without gassing him out of house and home with fumes.

We like how [Dan] just runs right ahead and puts the printer together. He even points out kludges on the machine that are holding it together long enough for him to print a more functional part for the 3D printer– on the 3D printer. We look forward to the next installment.

Learn To Program With Literate Programming

My heyday in programming was about five years ago, and I’ve really let my skills fade. I started finding myself making excuses for my lack of ability. I’d tackle harder ways to work around problems just so I wouldn’t have to code. Worst of all, I’d find myself shelving projects because I no longer enjoyed coding enough to do that portion. So I decided to put in the time and get back up to speed.

Normally, I’d get back into programming out of necessity. I’d go on a coding binge, read a lot of documentation, and cut and paste a lot of code. It works, but I’d end up with a really mixed understanding of what I did to get the working code. This time I wanted to structure my learning so I’d end up with a more, well, structured understanding.

However, there’s a problem. Programming books are universally boring. I own a really big pile of them, and that’s after I gave a bunch away. It’s not really the fault of the writer; it’s an awkward subject to teach. It usually starts off by torturing the reader with a chapter or two of painfully basic concepts with just enough arcana sprinkled in to massage a migraine into existence. Typically they also like to mention that the arcana will be demystified in another chapter. The next step is to make you play typist and transcribe a big block of code with new and interesting bits into an editor and run it. Presumably, the act of typing along leaves the reader with such a burning curiosity that the next seventeen pages of dry monologue about the thirteen lines of code are transformed into riveting prose within the reader’s mind. Maybe a structured understanding just isn’t worth it.

I wanted to find a new way to study programming. One where I could interact with the example code as I typed it. I wanted to end up with a full understanding before I pressed that run button for the first time, not after.

When I first read about literate programming, my very first instinct said: “nope, not doing that.” Donald Knuth, who is no small name in computing, proposes a new way of doing things in his Literate Programming. Rather than writing the code in the order the compiler likes to see it, write the code in the order you’d like to think about it along with a constant narrative about your thoughts while you’re developing it. The method by which he’d like people to achieve this feat is with the extensive use of macros. So, for example, a literate program would start with a section like this:

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Hacking The Tesla Model S Rear Drive Unit

[Jason Hughes] is a big fan of Tesla, he’s spent a lot of time hacking on them to figure out what fancy things the automaker is up to. His most recent adventures are with the rear drive unit of a Tesla Model S.

[Jason] has had some fame in the Tesla community before; his most publicized hack was finding the model number for Tesla’s next edition of their car hashed away in the firmware. For this project he procured a rear drive unit from… somewhere, and with some help got it onto his bench at home.

His first steps were to hook it up to some power and start sniffing the CAN bus for commands. It took him a few hours but he was able to get the motor turning. He kept working at it until he had the full set of commands. So, he hooked up circulating water to the unit for cooling, and put it through its paces (at one point the unit announced it was now traveling at 117mph).

In the end he was able to get all the features working, including generation! He even made his own board for contrl. Just listening to the motor spin up is satisfying. Videos after the break.

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Robot Moth Is Learning to Fly Like A Real Moth

Harvard University has had the flying robot insect market covered for a long time. However, their robot bee, while cool, was starting to bum them out. They wanted to put the battery and brain on the robocritter and have it fly around without a tether. Technology just wasn’t moving fast enough for them, so they’ve picked a different bug, this time a moth.

The Wyss Institute for Biologically Inspired Engineering at Harvard University is known for its Flying Winged Micro Air Vehicles or FWMAV. Which is a pretty good example of what happens when you let engineers name things. This FWMAV, weighs in at a hefty 3grams and has a 16mm wingspan. It also has propulsion, sensors, communication, brains, and power on board. Pretty impressive, the heaviest item is the motor!

The moth can produce 4g of thrust, and they’ve shown it capable of staying aloft once launched with a small catapult. Since they’ve proven that it can at least fly, the next steps are to figure out the dynamics of moth-based flight. Right now it stays pointed in the right direction with a very tiny tail fin like on an airplane. Real moths manage this feat with independent wing control, which the robot doesn’t have yet.

It will be a while before a we’ll see robot moths bumping into our computer monitors a night, stealing our passwords, but it’s a really cool exercise in robot miniaturization.

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It’s Time to Finally Figure Out How to Use KiCAD

KiCAD has been making leaps and bounds recently, especially since CERN is using it almost exclusively. However, while many things are the same, just enough of them are different from our regular CAD packages that it’s hard to get started in the new suite.

[Chris Gammell] runs Contextual Electronics, an online apprenticeship program which goes from concept to assembled electronics covering everything in between. To take the course you pay a nominal fee, but [Chris] posted a very excellent ten-part video series made during the last run of classes which you can watch without charge. The videos go through the basics of KiCAD while hitting the major points to consider when designing and manufacturing your electronics.

The project [Chris] chose is a simple circuit that blinks an LED with a 555. The first videos cover navigating KiCAD’s component schematic editor and library system. Next comes creating circuit schematics and component footprint creation. [Chris] covers PCB layout, the generation of Gerber files, and finally ordering the design from OSH Park — the purveyors of purple boards we’ve come to know and love. The series finishes up with simulating the circuit in LTSpice, ordering the parts, and finally soldering and debugging of the board. If all goes correctly you should now have a single blinking LED.

If the bright summer sun is burning your delicate skin, and you’d rather be locked inside with solder fumes, add this to your watch list now!

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How Does a Buck Converter Work Anyway?

[Great Scott] should win an award for quickest explanation of a buck converter. Clocking in at five and a half minutes, the video clearly shows the operating principles behind the device.

It starts off with the question, what should you do if you want to drop a voltage? Many of us know that we can dim and brighten an LED using the PWM on an Arduino, but a closer inspection with an oscilloscope still shows 5V peaks that would be dangerous to a 3.3V circuit. He then adds an inductor and diode, this keeps the current from dropping too fast, but the PWM just isn’t switching fast enough to keep the coil energized.

A small modification to the Arduino’s code, and the PWM frequency is now in the kHz range. The voltage looks pretty good on the oscilloscope, but a filter cap gets it to look nice and smooth. Lastly, he shows how when the load changes the voltage out looks different. To fix this a voltage divider feeds back the information to the Arduino, letting it change the PWM duty to match the load.

In the last minute of the video he shows how to hook up off-the-shelf switching regulators, whose support components are now completely demystified as the basic principles are understood. Video after the break.

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Pi Zero Digital Frame Kiosk Uses OTG Right

USB On-The-Go (OTG) is one of the fun aspects of the USB standard. There are feelings about the other aspects, but that one is alright. Regardless, [Francesco] realized one day that the £3 digital picture frames he purchased at a charity sale really didn’t care if the files on the thumb drive mysteriously changed all the time. It would just keep pulling and displaying the latest file at a blistering 0.2 frames per second. That’s right, the concept [Francesco] went after is to show changing data, even animations, with an update of one frame every five seconds!

raspberry-pi-zero-otg-picture-frame-weatherHis initial tests showed good for the concept — the Pi can easily emulate a mass storage device, feeding in data whenever the picture frame looks for it. In addition to the Pi Zero board he added an Ethernet shield, a voltage regulator, a camera, and even some infrared LEDS. We suppose there are dreams for the future.

He has been developing scripts for this rig by logging in through a VNC. A cron job runs his scripts at regular intervals, grabbing useful data and making it available as an image. For example, one script opens up the weather in Epiphany (a web browser), takes a screenshot, and saves that screenshot to the mass storage being emulated using USB OTG. The digital picture frame blissfully updates, unaware of its strange appendages. Now the real limiting factor is how much you can accomplish with your mad Bash skills.