It sucks that certain stuff in public is off-limits right now, like drinking fountains and coin-operated candy and gum machines — especially the fun kind where you get to watch your gumball take a twisting trip down the tower and into the collection bin. Hopefully there will be commercial contact-free machines one of these days that take NFC payments. Until then, we’ll have to make them ourselves out of cardboard and whimsy and Micro:bits.
[Brown Dog Gadgets] also used one of their Crazy Circuits Bit Boards, which is a Micro:bit-to-LEGO interface module for building circuits with conductive tape. There’s a distance sensor in the rocket’s base, and a servo to dispense the gumballs. This entire build is fantastic, but we particularly like the clever use of a LEGO Technic beam to both catch the gumball and prevent the next one from going anywhere. You can see it in action after the break.
I’ve always thought that there are three things you can do with metal: cut it, bend it, and join it. Sure, I knew you could melt it, but that was always something that happened in big foundries- you design something and ship it off to be cast in some large angular building churning out smoke. After all, melting most metals is hard. Silver melts at 1,763 °F. Copper at 1,983 °F. Not only do you need to create an environment that can hit those temperatures, but you need to build it from materials that can withstand them.
Turns out, melting metal is not so bad. Surprisingly, I’ve found that the hardest part of the process for an engineer like myself at least, is creating the pattern to be replicated in metal. That part is pure art, but thankfully I learned that we can use technology to cheat a bit.
When I decided to take up casting earlier this year, I knew pretty much nothing about it. Before we dive into the details here, let’s go through a quick rundown to save you the first day I spent researching the process. At it’s core, here are the steps involved in lost wax, or investment, casting:
Make a pattern: a wax or plastic replica of the part you’d like to create in metal
Make a mold: pour plaster around the pattern, then burn out the wax to leave a hollow cavity
Pour the metal: melt some metal and pour it into the cavity
I had been kicking around the idea of trying this since last fall, but didn’t really know where to begin. There seemed to be a lot of equipment involved, and I’m no sculptor, so I knew that making patterns would be a challenge. I had heard that you could 3D-print wax patterns instead of carving them by hand, but the best machine for the job is an SLA printer which is prohibitively expensive, or so I thought. Continue reading “How To Get Into Lost Wax Casting (with A Dash Of 3D Printing)”→
[Jan Mrázek] is no stranger at all to home-grown improvements with his Elegoo Mars SLA 3D printer, and there is a lot going on in his experimental multi-LED upgrade which even involved casting his own lens array. In the end it did speed up his prints by a factor of three to four, though he cooked an LCD to failure in the process. Still, it was a fun project done during a COVID-19 lockdown; as usual there is a lot to learn from [Jan]’s experiences but the mod is not something he necessarily recommends people do for themselves.
[Jan] started by wondering whether better print quality and performance could be obtained by improving the printer’s UV light source. The stock printer uses a single large UV LED nestled into a reflector, but [Jan] decided to try making a more precise source of UV, aiming to make the UV rays as parallel as possible.
Custom LED array molded in clear epoxy.
To do this, he took a two-pronged approach. One was to replace the single large UV LED with a 4×7 array of emitters plus heat sink and fans. The other was to make a matching array of custom lenses to get the UV rays as parallel as possible.
Casting one’s own lens array out of clear epoxy was a lot of work and had mixed results, but again, it was a lockdown project and the usual “is-this-really-worth-it” rules were relaxed. In short, casting a single custom lens out of clear epoxy worked shockingly well, but when [Jan] scaled it up to casting a whole 4×7 array of them, results were mixed. Mold deformation and artifacts caused by the areas between individual lenses robbed the end result of much of its promise.
More success was had with the array of UV emitters, which enabled faster curing thanks to higher power, but the heat needs to be managed. The stock emitter of the printer is about 30 W, and [Jan] was running his new array at 240 W. This meant a blazing fast one second exposure time per layer, but the heat generated by the new lighting was higher than anticipated. After only ten hours the LCD failed, probably at least in part due to the heat. [Jan] halved the power of the array down to 120 W and added an extra fan, which appears to have done the trick. Exposure time is two to three seconds per layer, and it’s up to 150 hours of printing without problems.
Again, it’s not a process [Jan] necessarily recommends to others (and he definitely recommends buying lenses if at all possible instead of casting them) but as usual there is a lot to learn from his frank sharing of results, both good and bad. We’ve seen 3D-printed lenses as well as adding WiFi connectivity to one of these hobbyist printers, and it’s great to see the spirit of hacking alive and well when it comes to these devices.
The Elegoo Mars is an affordable SLA (resin-based) 3D printer, and there are probably few that have seen more mods and experimentation than [Jan Mrázek]’s machine. The final design of his DIY flexible build plate is a refinement of his original proof of concept, which proved a flexible build platform can be every bit as useful on an SLA printer as it is for FDM; instead of chiseling parts off a rigid build platform, simply pop the flexible steel sheet off the magnetic base and flex it slightly for a much easier part removal process. His original design worked, but had a few rough edges that have since been ironed out.
[Jan]’s magnetic build platform.We love how [Jan] walks through all of the design elements and explains what worked and what didn’t. For example, originally he used a galvanized steel sheet which was easy enough to work with, but ended up not being a viable choice because once it’s bent, it stays bent. Spring steel is a much better material for a flexible build platform, but is harder for a hobbyist to cut.
Fortunately, it’s a simple job for any metal fabrication shop and [Jan] got a variety of thicknesses cut very cheaply. It turns out that the sweet spot is 0.3 mm (although 0.2 mm is a better choice for particularly fragile parts.) [Jan] also suggests cutting the sheet a few millimeters larger than the build platform; it’s much easier to peel the sheet off the magnetic base when one can get a fingertip under an edge, after all.
The magnetic base that the steel sheet sticks to is very simple: [Jan] converted a stock build platform by mounting an array of 20 x 20 x 1 mm magnets with 3M adhesive mounting tape. He was worried that resin might seep in between the magnets and cause a problem, perhaps even interfering with the adhesive; but so far it seems to be working very well. Resin is viscous enough that it never penetrates far into the gaps, and no effect on the adhesive has been observed so far.
Watch how easily parts are removed in the short video embedded below, in which [Jan] demonstrates his latest platform design.
With all the cool and useful parts you can whip up (relatively) quickly on a 3D printer, it’s a shame you can’t just print a PCB. Sure, ordering a PCB is quick, easy, and cheap, but being able to print one-offs would peg the needle on the instant gratification meter.
[Peter Liwyj] may just have come up with a method to do exactly that. His Instructables post goes into great detail about his method, which uses an Elegoo Mars resin printer and a couple of neat tricks. First, a properly cleaned board is placed copper-side down onto a blob of SLA resin sitting on the print bed. He tricks the printer into thinking the platform is all the way down for the first layer by interrupting the photosensor used to detect home. He lets the printer go through one layer of an STL file that contains his design, which polymerizes a thin layer of plastic onto the copper. The excess resin is wiped gently away and the board goes straight into a ferric chloride etching bath. The video below shows the whole process.
As simple as it sounds, it looks like it works really well. And [Peter] didn’t just stumble onto this method; he approached it systematically and found what works best. His tips incude using electrical tape as a spacer to lift the copper off the print surface slightly, cleaning the board with Scotchbrite rather than sandpaper, and not curing the resin after printing. His toolchain is a bit uncoventional — he used SketchUp to create the traces and exported the STL. But there are ways to convert Gerbers to STLs, so your favorite EDA package can probably fit in to the process too.
The uses of artificial intelligence and machine learning continue to expand, with one of the more recent implementations being video processing. A new method can “fill in” frames to smooth out the appearance of the video, which [LegoEddy] was able to use this in one of his animated LEGO movies with some astonishing results.
His original animation of LEGO figures and sets was created at 15 frames per second. As an animator, he notes that it’s orders of magnitude more difficult to get more frames than this with traditional methods, at least in his studio. This is where the artificial intelligence comes in. The program is able to interpolate between frames and create more frames to fill the spaces between the original. This allowed [LegoEddy] to increase his frame rate from 15 fps to 60 fps without having to actually create the additional frames.
While we’ve seen AI create art before, the improvement on traditionally produced video is a dramatic advancement. Especially since the AI is aware of depth and preserves information about the distance of objects from the camera. The software is also free, runs on any computer with an appropriate graphics card, and is available on GitHub.
Many of us have been inspired by the videos of the Falcon 9 booster, tall as an office building, riding a pillar of flame down to a pinpoint landing at Kennedy Space Center or on one of SpaceX’s floating landing pads in the ocean. It’s not often that we get to see science fiction fantasy become reality on such a short timescale, and while they might not be sold on the practicality of reusable rockets, even the most skeptical of observers have to admit it’s an incredible feat of engineering.
Though it can’t quite compare to the real thing, this 1:60 scale Falcon 9 lamp by [Sir Michael II] promises to bring a little of that excitement home every time you flick on the light. Combining a scratch built model of the reusable booster with some RGB LEDs, the hovering tableau recreates the tense final seconds before the towering rocket comes to a rest on its deployable landing legs. We imagine those last moments must seem like an eternity for the SpaceX engineers watching from home as well.
The LED “exhaust” without the fluff.
[Michael] walks readers through assembling the Falcon 9 model, which cleverly uses a 2 inch white PVC pipe as the fuselage. After all, why waste the time and material printing a long white cylinder when you can just buy one at the hardware store for a few bucks?
Dressed up with 3D printed details from Thingiverse user [twuelfing] and splashed with a bit of paint, it makes for a very convincing model. While the diameter of the pipe isn’t quite right for the claimed 1:60 scale, unless Elon Musk is coming over your place to hang out, we don’t think anyone will notice.
The rocket is attached to the pad with a piece of threaded steel rod, around which [Michael] has wrapped one meter of RGB LEDs controlled by an Arduino Uno. With some polyester fiber filler as a diffuser and a bit of code to get the LEDs flickering, he’s able to produce a realistic “flame” that looks to be coming from the Falcon 9’s center engine. While we admit it may not make a very good lamp in the traditional sense, it certainly gets extra points for style.
