Improving Exposure On A Masked SLA Printer

November 12, 2019 by Tom Nardi 6 Comments

It’s taken longer than some might have thought, but we’re finally at the point where you can pick up an SLA 3D printer for a few hundred bucks. These machines, which use light to cure a resin, are capable of far higher resolution than their more common FDM counterparts, though they do bring along their own unique issues and annoyances. Especially on the lower end of the price spectrum.

[FlorianH] recently picked up the $380 SparkMaker FHD, and while he’s happy with the printer overall, he’s identified a rather annoying design flaw. It seems that the upgraded UV backlight in the FHD version of the SparkMaker produces somewhat irregular light, which in turn manifests itself as artifacts on the final print. Due to hot spots on the panel, large objects printed on the SparkMaker show fairly obvious scarring.

Now you might expect the fix for this problem to be in the hardware, but he’s taken it in a different direction. These printers use an LCD panel to block off areas of the UV backlight, thereby controlling how much of the resin is exposed. This is technique is officially known as “masked SLA”, and is the technology used in most of these new entry level resin printers.

As luck would have it, the SparkMaker FHD allows showing various levels of grayscale on the LCD rather than a simple binary value for each pixel. At least in theory, this allows [FlorianH] to compensate for the irregular backlight by adjusting how much the UV is attenuated by the LCD panel. He’s focusing on the printer he personally owns, but the idea should work on any masked SLA printer that accepts grayscale values.

The first step was to map the backlight, which [FlorianH] did by soaking thin pieces of paper in a UV reactant chemical, and draping them over the backlight. He then photographed the illumination pattern, and came up with some OpenCV code that takes this images and uses the light intensity data to compensate for the local UV brightness underneath the sliced model.

So far, this method has allowed [FlorianH] to noticeably reduce the scarring, but he thinks it’s still possible to do better. He’s released the code for this backlight compensation script, and welcomes anyone who might wish to take a look at see how it could be improved.

An uneven backlight is just one of the potential new headaches these low-cost “masked” SLA printers give you. While they’re certainly very compelling, you should understand what you’re getting into before you pull the trigger on one.

Haptic Games Bring Fun To The Visually Impaired

November 12, 2019 by Kristina Panos 2 Comments

No matter what your parents might say, games are good for us. They teach us to manage resources and give us dopamine rewards just like eating and mating do. Even if you’re no good at games in general, they are still a fun distraction from life.

There are so many games out there that could be enjoyed by the visually impaired, except that they rely on visuals. For example, you can play Yahtzee with nothing more than five dice, a cup, pencil and paper, and knowledge of the rules and scoring. The biggest obstacles are differentiating the dice from each other and keeping score.

One of our esteemed 2019 Hackaday Prize Top 20 Finalists is [JanThar]’s Haptic Games. [JanThar]’s growing collection of games uses 3D printing, vibration motors, and RFID to replace visual cues with sensory feedback. Yahtzee-wise, there’s a set of printed dice and scorecards. The scorecards use spherical magnets and an abacus layout. [JanThar] is also working on a Memory game to teach Braille, though it could be adapted to pure Braille for the visually impaired. Each game piece contains an RFID chip, so players can hold it up to a reader to check what they have.

Our favorite might be the PONG game that’s built on [JanThar]’s 2017 Hackaday Prize entry, the HaptiVision vest. Through the magic of a 16×8 field of vibration motors, players can track the ball’s movement across their torso and control the paddles with a sliders. There’s a brief demo of the games after the break.

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HF Propagation And Earthquakes

November 12, 2019 by Dan Maloney 25 Comments

For all the successes of modern weather forecasting, where hurricanes, blizzards, and even notoriously unpredictable tornadoes are routinely detected before they strike, reliably predicting one aspect of nature’s fury has eluded us: earthquakes. The development of plate tectonic theory in the middle of the 20th century and the construction of a worldwide network of seismic sensors gave geologists the tools to understand how earthquakes happened, and even provided the tantalizing possibility of an accurate predictor of a coming quake. Such efforts had only limited success, though, and enough false alarms that most efforts to predict earthquakes were abandoned by the late 1990s or so.

It may turn out that scientists were looking in the wrong place for a reliable predictor of coming earthquakes. Some geologists and geophysicists have become convinced that instead of watching the twitches and spasms of the earth, the state of the skies above might be more fruitful. And they’re using the propagation of radio waves from both space and the ground to prove their point that the ionosphere does some interesting things before and after an earthquake strikes.

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Superconference Interview: Sam Zeloof

November 12, 2019 by Lewin Day 2 Comments

In less than four days, the fifth Hackaday Superconference kicks off in Pasadena, California, and it’s shaping up to be a hoot. With a cavalcade of exciting workshops and talks on offer, hackers and makers are pouring in from across the globe for this celebration of software, firmware, and hardware.

Of course, the real gift of Supercon is the personalities which make up this awesome community. [Sam Zeloof] is one such luminary, well known for producing his very own silicon integrated circuits in his parent’s garage. Not content to keep this knowledge to himself, [Sam] gave an amazing talk at the 2018 Supercon on just what goes into creating your own silicon fab on a budget.

Our very own [Mike Szczys] caught up with [Sam] for an interview, discussing being inspired by the work of [Jeri Ellsworth], as well as the finer points of getting into lithography at home. [Sam] will be in attendance at the 2019 Superconference, of course. While he won’t be on the speaking circuit this year, his brother [Adam] will be presenting a talk called Thermodynamics for Electrical Engineers: Why Did My Board Melt (And How Can I Prevent It)?, which is sure to be a must-see.

You really should be there, but alas tickets have been sold out for almost two months! Never fear, we’ll be livestreaming the event. Be sure to subscribe to Hackaday on Youtube to be notified when it all kicks off, around 10 AM Pacific Time on Saturday, November 16th. If you scored tickets and are heading to Supercon, we can’t wait to see you there — the badge hacking begins early Friday morning.

Be sure to check out Sam’s interview after the break!

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Cardboard Longboard Uses Quarter-Isogrid Structure

November 12, 2019 by Lewin Day 19 Comments

Skateboards are most typically crafted by hand, carved out of wood layered by care. However, many makers have sought to explore alternative techniques. [Technovation] decided to combine alternative materials and digital fabrication techniques to produce this attractive cardboard longboard.

The structure of the board was designed in Fusion 360, featuring a quarter isogrid design. The structure consists of stringers connected by ribs, all made of cardboard, with interlocking slots to hold everything together. 1/4″ plywood is then used to reinforce the truck mounts, and a top and bottom baseplate of 4mm acrylic is installed to protect the cardboard from damage.

The parts for the board are all laser cut, making production and assembly a snap. No glue is used, either – the structure is able to hold itself together perfectly well with its slotted construction. The team note that having a rider on the board does create some significant flex, but it hasn’t caused a failure in practice.

Skateboards are a popular maker project, and we’ve seen all kinds over the years. Modern manufacturing techniques are often brought to bear, or designs are created to solve tricky travel problems. Video after the break.

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Printed Arduino Turntable Takes Objects For A Spin

November 12, 2019 by Kristina Panos 5 Comments

Have you built a 3D scanner yet? There’s more than one way to model those curves and planes, but the easiest may be photogrammetry — that’s the one where you take a bunch of pictures and stitch them into a 3D model. If you build a scanner like [Brian Brocken]’s that does almost everything automatically, you might consider starting a scan-and-print side hustle.

This little machine spins objects 360° and triggers a Bluetooth remote tethered to an iPhone. In automatic mode, it capture anywhere from 2-200 pictures. There’s a mode for cinematic shots that shoots video of the object slowly spinning around, which makes anything look at least 35% more awesome. A third mode offers manual control of the turntable’s position and speed.

An Arduino UNO controls a stepper that moves the turntable via 3D printed-in-place bearing assembly. This project is a (vast) improvement over [Brian]’s hand-cranked version that we looked at over the summer, though both are works of art in their own right.

Our favorite part aside from the bearing is the picture-taking process itself. [Brian] couldn’t get the iPhone to play nice with HC-05 or -06 modules, so he’s got the horn of 9g servo tapping the shutter button on a Bluetooth remote. This beautiful beast is wide open, so fire up that printer. You can watch the design and build process of the turntable after the break.

Want to scan some really tiny things? Make a motorized microscope from movie machines.

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RISC-V: Why The ISA Battles Aren’t Over Yet

November 12, 2019 by Maya Posch 39 Comments

A computer processor uses a so-called Instruction Set Architecture to talk with the world outside of its own circuitry. This ISA consists of a number of instructions, which essentially define the functionality of that processor, which explains why so many ISAs still exist today. It’s hard to find that one ISA that works for as many distinct use cases as possible, after all.

A fairly new ISA is RISC-V, the first version of which was created back in 2010 at the University of California, Berkeley. Intended to be a fully open ISA, targeting both students (as a learning tool) and industrial users, it is claimed to incorporate a number of design choices that should make it more attractive for a number of applications.

In this article I’ll take a look behind the marketing to take stock of how exactly RISC-V differs from other open ISAs, including Power, SPARC and MIPS.

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