CAL 3D Printing Spins Resin Right Round, Baby

Computed Axial Lithography (CAL) is a lighting-fast form of volumetric 3D printing that holds incredible promise for the future, and [The Action Lab] filmed it in action at a Berkeley team’s booth at the “Open Sauce” convention.

The basic principle works like this: an extra-viscous photopolymer resin sits inside a rotating, transparent cylinder. As the cylinder rotates, UV light is projected into the resin in patterns carefully calculated to reproduce the object being printed. There are no layers, no FEP, and no stop-and-start; it’s just one long exposure from what is effectively an object-generating video, and it does not take long at all. You can probably guess that the photo above shows a Benchy being created, though unfortunately, we’re not told how long it took to produce.

Don’t expect to grab a bottle of SLA resin to get started: not only do you need higher viscosity, but also higher UV transmission than you get from an SLA resin to make this trick work. Like regular resin prints, the resolution can be astounding, and this technique even allows you to embed objects into the print.

This handle was printed directly onto the shaft of the screwdriver.

It’s not a new idea. Not only have we covered CAL before, we even covered it being tested in zero-G. Floating in viscous resin means the part couldn’t care less about the local gravity field. What’s interesting here is that this hardware is at tabletop scale, and looks very much like something an enterprising hacker might put together.

Indeed, the team at Berkeley have announced their intention to open-source this machine, and are seeking to collaborate with the community on their Discord server. Hopefully we’ll see something more formally “open” in the future, as it’s something we’d love to dig deeper into — and maybe even build for ourselves.

Thanks to [Beowulf Shaeffer] for the tip. If you are doing something interesting with photopolymer ooze (or anything else) don’t hesitate to let us know! Continue reading “CAL 3D Printing Spins Resin Right Round, Baby”

Playing DOOM On The Anker Prime Charging Station

At this point the question is no longer whether a new device runs DOOM, but rather how well. In the case of Anker’s Prime Charging Station it turns out that it’s actually not too terrible at controlling the game, as [Aaron Christophel] demonstrates. Unlike the similar Anker power bank product with BLE and a big display that we previously covered, this device has quite the capable hardware inside.

Playing a quick game of Doom while waiting for charging to finish. (Credit: Aaron Christophel, YouTube)
Playing a quick game of DOOM while waiting for charging to finish. (Credit: Aaron Christophel, YouTube)

According to [Aaron], inside this charging station you’ll not only find an ESP32-C3 for Bluetooth Low Energy (BLE) duty, but also a 150 MHz Synwit SWM341RET7 (Chinese datasheet) ARM-based MCU along with 16 MB of external flash and 8 MB of external RAM. Both of these are directly mapped into the MCU’s memory space. The front display has a 200×480 pixel resolution.

This Synwit MCU is a bit of a curiosity, as it uses ARM China’s Star-MC1 architecture for which most of the information is in Chinese, though it’s clear that it implements the ARMv8-M profile. It can also be programmed the typical way, which is what [Aaron] did to get DOOM on it, with the clicky encoder on the side of the charging station being the sole control input.

As can be seen in the video it makes for a somewhat awkward playing experience, but far more usable than one might expect, even if running full-screen proved to be a bit too much for the hardware.

Continue reading “Playing DOOM On The Anker Prime Charging Station”

A photo for a motor and a meter on a bench.

Let’s Brief You On Recent Developments For Electrostatic Motors

Over on his YouTube channel [Ryan Inis] has a video about how electrostatic motors are breaking all the rules.

He explains that these days most motors are electromagnetic but suggests that may be changing as the age-old principles of electrostatics are being explored again, particularly due to the limited supply of rare-earth magnets and other materials (such as copper and steel) which are used in many electromagnetic motors.

[Ryan] says that new electrostatic motors could be the answer for highly efficient and economical motors. Conventional electromagnetic motors pass current through copper windings which create magnetic fields which are forces which can turn a rotor. The rotor generally has permanent magnets attached which are moved by the changing magnetic forces. These electromagnetic motors typically use low voltage and high current.

Electrostatic alternatives are actually an older design, dating back to the 1740s with the work of Benjamin Franklin and Andrew Gordon. These electrostatic motors generate motion through the attraction and repulsion of high voltage electric charges and demand lower current than electromagnetic motors. The high voltages involved create practical problems for engineers who need to harness this energy safely without leading to shocks or sparks or such.

[Ryan] goes on to discuss particular electrostatic motor designs and how they can deliver higher torque with lower energy losses due to friction and heat making them desirable for various applications, particularly industrial applications which demand low speed and high torque. He explains the function of the rotor and stator and says that these types of motors use 90% less copper than their electromagnetic alternatives, also no electrical steel and no permanent magnets.

For more coverage on electrostatic motors check out Electrostatic Motors Are Making A Comeback.

Continue reading “Let’s Brief You On Recent Developments For Electrostatic Motors”

One-Motor Drone Mimics Maple Seeds For Stability

We’ve seen aircraft based on “helicopter” seeds (technically samara seeds, which include those of maples and elms) before, but this recent design from researchers at the Singapore University of Technology and Design (SUTD) shows how a single small motor can power a spinning monocopter capable of active directed flight, including hovering.

The monocopter is essentially an optimized wing shape with a single motor and propeller at one end. Hardware-wise it might be simple, but the tradeoff is higher complexity in other areas. Physical layout and balance are critical to performance, and software-wise controlling what is basically a wing spinning itself at high speed is a complex task. The payoff is highly-efficient flight in a package that self-stabilizes; it weighs only 32 grams and has a flight time of 26 minutes, which is very impressive for a self-contained micro aircraft.

We saw what looks like an earlier version of this concept from SUTD that was capable of directed flight by modifying the airfoil surface, but like the seeds it was modeled after, it’s more of a glider. This unit has the same spinning-seed design, but is actively powered. A significant improvement, for sure.

For those who prefer their DIY micro aircraft a little more traditional-looking, be sure to check out the design details of a handmade and fully operational 1:96 scale P-51 Mustang that weighs only 2.9 grams. It even has retractable landing gear! When one can manage to keep mass to a bare minimum, a little power goes a long way.

Carry Your Grayscale Memories With This Tiny Game Boy Photo Frame

While we cannot be certain this is the world’s smallest digital photo frame, [Raphaël Boichot]’s Pico Slide Show is probably in the running. Since the 0.85″ TFT display would be wasted on multi-megapixel images, [Raphael] has dedicated this project to images from the Game Boy Camera.

It’s a good fit: the tiny square display has a resolution of 128 pixels per side, while the Game Boy Camera produces files measuring 128 x 112. That allows for pixel-perfect rendering of the grainy images from everyone’s favorite early digicam with just a little letter boxing.

While perfect for all your on-the-go Game Boy slideshow needs, an enclosure might be a good idea for hauling around that battery.

The brains of the operation are an RP2040, provided via the RP2040-zero breakout from Waveshare. Since everything is through-hole or on breakouts, this wouldn’t be a bad project for a beginner solderer.

Since it would make no sense not to have this tiny unit to be portable, power is provided with a 503035 LiPo pouch on the back. It’s only 500 mAh, but this device isn’t going to be chugging power, so we’d expect a reasonable runtime.

Alas, no link cable functionality is currently included, and files must be transferred via PC. Images are saved to the Pico’s flash memory, and [Raphaël] says any format from any Game Boy Printer emulator will work, provided it has a four-color palette. The flash memory on the chip has room for 540 images, which seems like more than enough. Regardless of the novelty of the tiny screen and retro format, nobody wants to see that many holiday snaps in one go.

The Game Boy Camera has been popular with hackers literally for decades now, and we’ve seen it everywhere from wedding photo booths to the heart of a custom DSLR, and even on Zoom calls.

Hide Capacitive Touch Buttons In Your Next 3D Print

Capacitive touch sensors are entirely in the domain of DIY, requiring little more than a carefully-chosen conductive surface and a microcontroller. This led [John Phillips] to ask why not embed such touch buttons directly into a 3D print?

Button locations and labels can be made as part of the 3D print, which is handy.

The process is not much different from that of embedding hardware like magnets or fasteners into 3D prints: one pauses the print at convenient spot, drops in the necessary hardware, then resumes printing. It’s more or less the same for embedding a touch-sensitive button, but [John] has a few tips to make things easier.

[John] suggests using a strip of copper tape, one per touch pad, and embedding it into the print near the surface. His preference is three layers in, putting the copper tape behind 0.6 mm of plastic when using standard 0.20 mm layer heights.

Copper tape makes a good capacitive touch sensor, and the adhesive on the tape helps ensure it stays in place as the 3D printer seals it in on subsequent passes.

Copper tape is also easy to solder to, so [John] leaves a small hole over the copper — enough to stick in a wire and tack it down with the tip of a soldering iron and a blob of solder after the print is complete. It might not be ideal soldering conditions, but if things get a little melty on the back side it’s not the end of the world.

On the software side capacitive touch sensors can be as simple as using an Arduino library for the purpose but [John] rolled his own code, so give it a peek.

This reminds us a bit of another way to get a capacitive touch sensor right up against some plastic: a simple spring can do the trick.