# Toddler Arcade Cabinet Is A Stand-Up Job

A few years ago, [Mark] built an arcade cabinet into a low table. But once his new gaming buddy [Grayson] came along and started crawling, it wasn’t practical to have a low, pointy table around. Trouble is, [Mark] had already given [Grayson] his first taste with a Thomas the Tank Engine game. Since the kid was hooked, [Mark] rebuilt the table arcade into a toddler-sized arcade cabinet that they can both use.

The brain — a Raspberry Pi running RetroPie — should be familiar to most of our readers. [Mark] found the perfect crappy old monitor when they were upgrading at his office, and found some nice speakers to give it good bass. We love the details like the chrome edging, and especially the kick bar/footrest along the bottom. It can be difficult to decide how to decorate a multi-arcade cabinet, so [Mark] went the sticker bomb route with 700 of them randomly distributed and safe from toddler wear and tear under five coats of clear wood varnish.

We think this looks great, especially since [Mark] doesn’t have a workshop and cut all that MDF by hand on a jigsaw in the kitchen. Check out the happy train engineer after the break.

# Getting Started With Geometric Algebra For Robotics, Computer Vision And More

[Hugo Hadfield] wrote to let us know about an intriguing series of talks that took place in February of this year at GAME2020, on the many applications of geometric algebra. The video playlist of these talks can be found here along with the first video embedded after the break. For those of us who did not take advanced algebra during university, one can picture geometric algebra (GA) as an extension of vector algebra, adding more algebraic structures.

The essential difference is that GA adds a new vectors product, called the ‘geometric product’. The Cliff’s Notes version is that this is very useful for doing for example transformations, like in 3D spaces. For a quick algebraic introduction to GA for those familiar with vector algebra, the associated biVector website is helpful, from where one can also find additional information, software and other resources on getting started with GA.

These talks will take the viewer through the use of GA with robot kinematics (co-presented by [Hugo]), in astrophysics and AI. Definitely worth a watch, even algebra isn’t one’s strongest points.

# Making A Halloween Costume Fit For 2020

All across the country, parents are wondering what to do about the upcoming Trick Or Treat season. Measures such as social distancing, contact free treats, or simply doing it at home are all being weighed as a balance of fun and safety. [BuildXYZ] has decided to lean into the challenges this year and incorporate a mask as part of the costume for his boys.

It started with a 3d printed mask, printed in two halves, and sealed with silicon caulk and N95 filter material in the inlet and outlet holes on the sides. The real magic of the mask is the small OLED screen mounted to the front that works along with a small electret microphone inside the mask. By sampling the microphone and applying a rolling average, the Arduino Nano determines if the mouth drawn on the display should be open or closed. A small battery pack on a belt clip (with a button to flash “Trick or Treat” on the screen) powers the whole setup and can be easily hidden under a cape or costume.

This isn’t the first hack we’ve seen for Halloween this year, such as this socially distant candy slide. We have a feeling that there will be many more as the month rolls on and people start to apply their ingenuity to the season.

# Making A Modern Version Of A Steam Engine From Antiquity

Imagine traveling back in time about 2,200 years, to when nothing moves faster than the speed at which muscle or wind can move it. Think about how mind-shattering it would have been to see something like Hero’s Engine, the first known example of a steam turbine. To see a sphere whizzing about trailing plumes of steam while flames licked around it would likely have been a nearly mystical experience.

Of course we can’t go back in time like that, but seeing a modern replica of Hero’s Engine built and tested probably isn’t too far from such an experience. The engine, also known as an aeolopile, was made by the crew over at [Make It Extreme], whose metalworking videos are always a treat to watch. The rotor of the engine, which is fabricated from a pair of hemispherical bowls welded together, is supported by pipes penetrating the lid of a large kettle. [Make It Extreme] took great pains to make the engine safe, with relief valves and a pressure gauge that the original couldn’t have included. The aeolopile has a great look and bears a strong resemblance to descriptions of the device that may or may not have actually been invented by Greek mathemetician [Heron of Alexandria], and as the video below shows, when it spins up it puts on a great show.

One can’t help but wonder how something like this was invented without someone — anyone — taking the next logical step. That it was treated only as a curiosity and didn’t kick off the industrial revolution two millennia early boggles the mind. And while we’ve seen far, far simpler versions of Hero’s Engine before, this one really takes the cake on metalworking prowess.

# Gesture Controller For Roku And Universal Keyboard Built By UCPLA Dream Team

The coolest part of this year’s Hackaday Prize is teaming up with four nonprofit groups that outlined real-world challenges to tackle as part of the prize. To go along with this, the Dream Team challenge set out a two-month design and build program with small teams whose members each received a \$6,000 stipend to work full time on a specific build.

The work of the Dream Team project is in, and today we’re taking a look at United Cerebral Palsy of Los Angeles (UCPLA) project which not only designed and built a universal remote for those affected with this condition, but also went to great lengths to make sure that “universal” was built into the software and user experience just as much as it was built into the hardware itself. Join us after the break for a closer look a the project, and to see the team’s presentation video.

# 3D Printering: Wash Parts Better And Make Solvent Last Longer

SLA printing in resin is great, but part washing can be a hassle. The best results come from a two-stage wash, but that also means more material and more processing steps. Fortunately, there are ways to make it easier and more effective. One such way is to use a part washing machine, and I’ll cover a DIY option to make your own, but despite what the advertising implies for the commercial ones, a wash machine isn’t a cure-all.

Let’s go through how to get the best results from part washing, how to make the solvent last as long as possible, and how to dispose of the eventual waste.

## Resin-Printed Parts Need Washing

All parts printed in resin emerge from the printer coated in syrupy, uncured goop. This needs to be removed completely, or the print ends up sticky and no amount of drying or additional UV curing will change that. (There is a way to fix sticky prints, but it’s better to avoid the situation in the first place.)

Simple part washing can be done with nothing more than a jar in which to rinse and soak a small part for about ten minutes, but agitation and a secondary wash will go a long way toward better and more consistent results. As mentioned, part washing machines like to present themselves as a one-appliance solution, but best results still come from a two-stage wash, and that means some additional steps.

# Scratch-Built XY Table Gets The Job Done

Unless you have one large pile of cash to burn through, properly equipping a workshop can take years of burning through little piles of cash. Whether to save a bit of cash or simply for the challenge, [Workshop from Scratch] is doing exactly what his channel name suggests, and his latest project is a XY table. (Video, embedded below.)

A XY table, or cross table, allows a workpiece to be translated in two dimensions, usually on a drill press or milling machine. On a drill press they make repetitive task like drilling a series of holes simpler and quicker. [Workshop from Scratch] built most of the frame with steel flat bar, and the moving parts run on ground steel rods with linear bearings. Lead screws with hand wheels are used to translate the table.

A machine like this requires the opposing plates of each table to be perfectly aligned, which [Workshop from Scratch] achieved by spot welding the matching plates together and drilling them in one operation. He also added T-slot top surface, created by welding wide flat bar on top of narrower flat bar.

With the lack of dials, it doesn’t look like it’s meant for precision work, but we would still be interested to know how repeatable the lead screw positioning is. Regardless, it’s still a useful addition to the shop.

[Workshop from Scratch] is building a rather impressive collection of DIY tools, including a magnetic vise (that he already used with the XY table), magnetic drill press and a hydraulic lift table. We look forward to seeing what’s next on the list. Continue reading “Scratch-Built XY Table Gets The Job Done”