When it comes to hobby-level 3D printing, most of us use plastic filament deposited by a hot end. Nearly all the rest are using stereolithography — projecting light into a photosensitive resin. Filament printers have typical build volumes ranging from 1,000 to 10,000 cubic centimeters and even larger isn’t unusual. By contrast, SLA printers are often much smaller. A 1,200 CC SLA printer is typical and the cheaper printers are sometimes as little as 800 CCs. Perhaps that’s why [3D Printing Nerd] (otherwise known as [Joel]) was excited to get his hands on a Peopoly Phenom which has a build area of over 17,000 CCs. You can see the video review, below.
He claims that it is even bigger than a Formilab 3L, although by our math that has a build volume of around 20,000 CCs. On the other hand, the longest dimension on the Peopoly is 40 cm which is 6.5 cm longer than the 3L, so maybe that’s what he means. Either way, the printer is huge. That’s nearly 16 inches which is big even for a filament printer. Regardless of which one is bigger, the Peopoly is certainly much less expensive coming in at around $1,800 versus the 3L’s almost $10,000 price tag.
If you thought CADing designs for 3D printing was hard enough, wait until you hear about this .stl trick.
[Angus] of Maker’s Muse recently demoed a method for creating hidden geometries in .stl files that are only revealed during the slicing process before a 3D print. (Video, embedded below.) The process involves creating geometries with a thickness smaller than the size of the 3D printer’s nozzle that still appear to be solid in a .stl editor, but will not be rendered by a FDM slicer.
Most 3D printers have 0.4 mm thickness nozzle, so creating geometries with a wall thinner than this value will result in the effect that you’re looking for. Some possible uses for this trick are to create easter eggs or even to mess with other 3D printing enthusiasts. Of course, [Angus] recommends not to use this “deception for criminal or malicious intent” and I’d have to agree.
There’s a few other tricks that he reveals as well, including a way to create a body that’s actually a thin shell but appears to be solid: great for making unprintable letters that reveal hidden messages.
Nevertheless, it’s a cool trick and maybe one of those “features not bugs” in the slicer software.
Transformers are deceptively simple devices. Just coils of wire sharing a common core, they tempt you into thinking you can make your own, and in many cases you can. But DIY transformers have their limits, as [Great Scott!] learned when he tried to 3D-print his own power transformer.
To be fair, the bulk of the video below has nothing to do with 3D-printing of transformer coils. The first part concentrates on building transformer cores up from scratch with commercially available punched steel laminations, in much the same way that manufacturers do it. Going through that exercise and the calculations it requires is a great intro to transformer design, and worth the price of admission alone. With the proper number of turns wound onto a bobbin, the laminated E and I pieces were woven together into a core, and the resulting transformer worked pretty much as expected.
The 3D-printed core was another story, though. [Great Scott!] printed E and I pieces from the same iron-infused PLA filament that he used when he 3D-printed a brushless DC motor. The laminations had nowhere near the magnetic flux density of the commercial stampings, though, completely changing the characteristics of the transformer. His conclusion is that a printed transformer isn’t possible, at least not at 50-Hz mains frequency. Printed cores might have a place at RF frequencies, though.
In the end, it wasn’t too surprising a result, but the video is a great intro to transformer design. And we always appreciate the “DIY or Buy” style videos that [Great Scott!] does, like his home-brew DC inverter or build vs. buy lithium-ion battery packs.
Some 3D printers will give you prints with surfaces resembling salmon skin – not exactly the result you want when you’re looking for a high-quality print job. On bad print jobs, you can usually notice that the surface is shaking – even on the millimeter scale, this is enough to give the print a bumpy finish and ruin the quality of the surface. TL smoothers help with evening out the signal going through stepper motors on a 3D printer, specifically the notoriously noisy DRV8825 motor drivers.
Analyzing the sine wave for the DRV8825 usually shows a stepped signal, rather than a smooth one. Newer chips such as the TMC2100, TMC2208, and TMC2130 do a much better job at providing smooth signals, as do cheaper drivers like the commonly used A4988s.
[Fugatech 3D Printing] demonstrates some prints from a D-Force Mini with an MKS Base 1.4 smoother-based control board, which is easier to use and smarter than Marlin. On the two prints using smoothers, one uses a board with four diodes, while the other was printed with a board with eight diodes. [Mega Making] compares how the different motor drivers work and experimentally shows the stuttering across the different motors before and after connecting to the smoothers.
The yellow and pink traces are the current for each phase of the motor. The blue and green traces are the voltages on each terminal of the phase with the yellow current. [via Schrodinger Z]A common problem with DRV8825 motors is their voltage rating, which is lower than most supplies. When a 3D printer is moving slower than 100mm/min, the motor is unable to move smoothly.
[Schrodinger Z] does a bit of digging into the reason for the missing microsteps, testing out different decay modes in DRV8825s and why subharmonic oscillations occur in the signals from the motor.
The driver consequently has a “dead zone” where it is unable to produce low currents. Modifying the motor by offsetting the voltage by 1.4V (the point where no current flow) would allow the dead zone to be bridged. This also happens to be the logic behind the design for smoothers, although it is certainly possible to use different diodes to customize the power losses depending on your particular goal for the motor.
Debugging signal problems in a 3D printer can be a huge headache, but it’s also gratifying to understand why microstepping occurs from current analysis.
While we know some 3D printer operators who need coffee, Washington State University is showing an improved PLA material that incorporates used coffee waste. Regular PLA is not known for being especially strong, though It isn’t uncommon for vendors to add things to their PLA to change its characteristics.
The new material containing about 20% coffee waste showed an over 400% increase in toughness (25.24 MJ/m3) versus standard PLA. Why coffee waste? We aren’t sure. They didn’t add grounds, but rather a dry and odorless material left over after coffee grounds are processed for biodiesel production.
An Elegoo Mars resin 3D printer, straight to my doorstep for a few hundred bucks. What a time to be alive.
Resin-based 3D printers using digital light processing (DLP) and especially stereolithography (SLA) are getting more common and much more affordable. Prosumer-level options like Formlabs and the Prusa SL1 exist, but more economical printers like the Elegoo Mars, Anycubic Photon, and more can be had for a few hundred bucks. Many printers and resin types can even be ordered directly from Amazon, right at this moment.
Resin prints can look fantastic, so when does it make sense to move to one of these cheap resin printers? To know that, consider the following things:
The printing process and output of resin printers is not the same as for filament-based printers. Design considerations, pre-processing, and post-processing are very different.
Resin printing has a different workflow, with consumables and hidden costs beyond the price of resin refills.
Need a quick way to tell your temperature before work tomorrow? Student maker [The Marpe] recently fashioned a sleek home-use thermal camera that even looks like a point and shoot. It works as an Android hardware add-on by integrating the readings from a MLX90640 far-infrared (FIR) thermal sensor with a STM32F042F6Px microcontroller. All this connects to an Android application via USB (MicroUSB or Type C).
On the app, users are able to view, take photos, and display the resulting thermal images from the open thermal camera. The code for the open Android application is also available on his GitHub.
The FIR sensors contain a small array of IR pixels, integrated to measure the ambient temperature of the internal chip, and supply sensor to measure the VDD. Each pixel on the sensor array responds to the IR energy focused on it to produce an electronic signal, which is processed by the camera processor to create a map of the apparent temperature of the object. The outputs of the sensors and VDD are stored in an internal RAM and are accessible through 3.3V I2C. They’re not only low-cost and fairly high resolution, but also available by order on Digi-Key.
The microcontroller is based on the STM32 platform, with 32-bit performance, low-power operation (at 2V to 3.6V and 48 MHz) and is fairly low-cost. The custom-designed PCBs are fitted inside a 3D-printed casing with M2.5 inserts to ease assembly. [The Marpe] used an Esra soldering iron to create a heat insert tool for easier assembly and more consistent results with the heat inserts, which made for a nicer overall finish.
The project has since been presented at the Ljublana Mini Maker Faire in Slovenia and the Trieste Mini Maker Faire in Italy. Here, the open thermal camera is being tested out on a faulty PCB with a shorted component, showing the location of the short on the Android application’s thermal camera display.
Other uses for the camera could be home insulation inspection, water leakage detection, wildlife observation, or even figuring out if your soldering iron is hot enough to use. We’ll say it’s a pretty useful DIY project!
