Cleaner Laser Cutting With A 3D-Printed Nozzle

November 25, 2020 by Donald Papp 24 Comments

[Nervous System] does a lot of laser cutting, and [Jesse] shared a fascinating experimental improvement to their laser cutter that consists of a 3D-printed nozzle for cleaner cuts. You can see the results for yourself above, where the difference between the two cuts is striking.

[Jesse]’s modification doesn’t affect the laser beam itself; it is an improvement on the air assist, which is the name for a constant stream of air that blows away smoke and debris as the laser burns and vaporizes material. An efficient air assist is one of the keys to getting nice clean laser cuts, but [Jesse] points out that a good quality air assist isn’t just about how hard the air blows, it’s also about how smoothly it does so. A turbulent air assist can make scorch marks worse, not better.

3D-printed nozzle to promote laminar air flow on the left, stock nozzle on the right.

As an experiment to improve the quality of the air flowing out the laser nozzle, [Jesse] researched ways to avoid turbulence by creating laminar flow. Laminar flow is the quality of a liquid having layers flowing past one another with little or no mixing. One way to do this is to force liquid through individual, parallel channels as it progresses towards a sharply-defined exit nozzle. While [Jesse] found no reference designs of laminar flow nozzles for air assists, there were definitely resources on making laminar flow nozzles for water. It turns out that interest in such a nozzle exists mainly as a means of modifying Lonnie Johnson’s brilliant invention, the Super Soaker.

Working from such a design, [Jesse] created a custom nozzle to help promote laminar flow. Sadly, a laser cutter head carries design constraints that make some compromises unavoidable; one is limited space, and another is the need to keep the laser’s path unobstructed. Still, after 3D printing it in rigid heat-resistant resin, [Jesse] found a dramatic improvement in the feel of the air exiting the nozzle. Some test cuts confirmed a difference in performance, which results in a noticeably cleaner kerf without scorching around the edges.

One of the things [Nervous System] does is make their own custom puzzles, so any improvement to laser cutting helps reliability and quality. When production is involved, just about everything matters; a lesson [Nervous System] shared when they discussed making the best plywood for creating their puzzles.

Building One Test Fixture To Rule Them All

May 31, 2020 by Donald Papp 3 Comments

Test and programming fixtures are great time-savers for anyone who needs to deal with more than a handful of PCBs. Instead of plugging in connectors (or awkwardly holding probe tips or wires) to program some firmware or run tests, one simply pops a PCB into a custom fixture with one hand, and sips a margarita with the other while a program decides whether everything is as it should be. Test fixtures tend to be custom-made for specific board layouts, meaning one tester is needed per board or device type, but this work is easily justified by the huge time savings they offer.

An inserted PCB sits atop the thick acrylic piece, with pogo pins making contact from below. Generous space on the left and right make sure there is clearance for any mounted components. Visible near the bottom of the green board are output LEDs, and two touch-sensitive pads.

But the fine folks at Sparkfun’s quality control department figured they could save even more time by exploiting common design features across different boards, and shared details about designing a single test fixture flexible enough to handle multiple board types and designs.

The test unit looks like pretty familiar stuff at first glance: some hardware responsible for running the test program, laser-cut acrylic jig to hold a test PCB in a consistent position, spring-loaded pogo pins to make temporary electrical connections, and LEDs to clearly indicate PASS and FAIL states. The clever part is the way the fixture is designed to accommodate multiple board designs, and how it uses several 74LVC4066 quad bilateral switch ICs to take care of switching which pogo pins are connected and to where.

As mentioned, to be compatible with multiple boards there must be common design elements to exploit. In Sparkfun’s case, the through-hole connections on their breakout boards are all in a row with standard 0.1″ spacing. By using the aforementioned pogo pins and 4066 ICs, different pinouts can be accommodated and multiple board types can be used without any need to swap to different test hardware.

Test and programming fixtures, being one-offs, tend to have a lot of space for creativity and often show clever design or re-purposing of parts. Our own [Bob Baddeley] explains all about them here.

A Foam Core Stand Against Tablet Design

May 20, 2020 by Kristina Panos 11 Comments

We hadn’t considered how challenging it might be to try drawing long-term on a tablet, and it sounds as though Apple didn’t, either. According to [Eric Strebel], who normally designs products for other people, there are many problems to solve. The camera area creates a bump on an otherwise flat backside, so it wobbles on the table. It’s thick. It’s too easy to run your stylus off the side.

Yes there are tablet holders out there, even a few with cup holders, but almost none of them have a kickstand for holding the thing vertically. If you want something done right, you have to do it yourself. And so [Eric] designed his ideal stand to solve all of these problems (video, embedded below). It’s mostly made of laser-cut foam core board, with some layers of poster board added to make the bezel totally flush with the tablet.

[Eric] can snap the tablet in place and use it flat, or fold back the upper half into a stand. It even works well over on the couch, or sitting up in bed. We particularly like the window gasket feet and all the versions of his hinges, which start with strips of cheesecloth and end in grosgrain ribbon. [Eric]’s approach to design always reminds us to keep an open mind about materials and methods. If you try using what you already have, the results may surprise you. Check out the build video after the break.

Maybe you don’t need or want a tablet stand. How about a foam core spray booth?

Continue reading “A Foam Core Stand Against Tablet Design” →

Eavesdropping Assistant Disturbs The Sound Of Silence

March 22, 2020 by Sven Gregori 12 Comments

Unless you happen to be from Finland, this is just an all too familiar situation: you’re stuck in an inescapable situation with this one person who is really more of an acquaintance than a friend, and neither of you knows who should say something in hopes of keeping a conversation going. Awkward silence is inevitable, and the longer it lasts, the more excruciating the thought of opening your mouth becomes. Well, consider those days over, thanks to [Jasper Choi] and his friends, who blessed us with the System for Awkward Silence Solution and Interaction Enhancer, or SASSIE.

Built as a laser-cut rotating cylinder, and equipped with a pair of microphones, SASSIE detects and counts the duration of any ongoing silence in the room. Once a pre-defined time limit is reached, it rotates itself to a random direction, symbolically pointing a finger to one of the people present in the room to indicate its their turn to speak now. To break the silence right off the bat, the finger pointing is accompanied by some pre-recorded messages. Unfortunately the audio files exceeded the storage of the Arduino Uno used here, so the responsibilities had to be divided between two Arduinos, arranged with the help of some simple serial communication.

While this is obviously a tongue-in-cheek project, it might just be a welcoming relieve for people with social anxiety, and there is definitely potential to take the idea further. Maybe with some inspiration from this happy robot fellow, a future version might ease the conversation even further by suggesting a topic along the way.

Continue reading “Eavesdropping Assistant Disturbs The Sound Of Silence” →

An Armored Vehicle From Foam Core And Big Box Toys

March 19, 2020 by Tom Nardi 7 Comments

Over the last several months, [Eric Strebel] has been working on a concept for an electric-powered infantry combat vehicle. We don’t think he’s been contracted by any nation’s military to design this vehicle, but as a product designer we imagine he does this sort of thing to keep himself sharp. In any event, it’s been fun to watch from the sidelines.

In the latest installment in this series of videos, [Eric] turns his earlier concept art into a functional prototype; albeit at somewhat reduced scale. Still, building any kind of vehicle from the ground up is no easy feat and it’s fascinating to watch the process.

The futuristic faceted look of the vehicle’s armor plate makes for an exceptionally time-consuming build, as he has to cut and glue each piece of foam core into place. Some of the smaller pieces seem to have the tell-tale char marks from a trip through the laser cutter, but in the video after the break you can see that the larger panels are hand cut with a razor.

The plan was originally to just make a static mock-up of the vehicle, but thanks to a pair of remote controlled trucks that [Eric] found at this local Big Box retailer, this foam fighter ended up getting an upgrade. After liberating the motors and gearboxes from the two trucks, he 3D printed axle extensions to take into account the wider track of his vehicle, and built his “tub” around it. While the R/C gear is clearly on the low end of the spectrum, the overall effect looks great as the vehicle is bounding around the yard.

Readers of Hackaday will no doubt be well aware of [Eric Strebel] and his many talents. From 3D scanning via photogrammetry to embedding electronics into flexible molded parts, you’re sure to learn something new from following this prolific maker.

Continue reading “An Armored Vehicle From Foam Core And Big Box Toys” →

Why Settle For The Standard Catan Board?

February 9, 2020 by Kristina Panos 3 Comments

Let’s face it, game night can get downright rowdy. Whether your game nights involve wine and cats, beer and dogs, or vodka and bear cubs, things happen. Maybe the robber gets batted irretrievably far under the couch, or someone gesticulates wildly and spills wine all over your sheep. [EEEEEEEEEDEN]’s gatherings were getting way out of hand, and it was time to design a custom Catan board.

But she didn’t stop with the board tiles — this is Catan redesigned from the ground up, including the pieces, the resource cards, and a custom storage box. [EEEEEEEEEDEN] even planned for player expansion by designing a leaf to drop in the middle. There are a few hundred magnets built into the frame, so there shouldn’t be any more lost pieces. And as far as liquor-proofing all the cardboard goes, [EEEEEEEEEDEN] designed new board tiles and cards, laser cut them from acrylic, and painstakingly painted them all with Plasti-Dip spray.

We think it’s gorgeous, but understand that maybe this minimalist style isn’t for everyone. If you want to go custom, it’s hard to argue against the beauty of 3D Catan.

Thanks to [Johannes] for the tip! via /r/DIY

Array Of Useless Machines Is Useless

February 5, 2020 by Richard Baguley 38 Comments

What’s the collective noun for a group of useless machines? A passel of useless machines? A failure? A waste? A 404? Whatever you want to call it, [Martin Raynsford] has produced one here with this collection of 24 useless machines arranged into a 5 by 6 array. He produced it for an event at a hackerspace to amuse visitors, and it certainly seems to do the job in the video after the break.

[Martin] built the case by modifying the design of his Useless Machine kit, stretching out the case to hold multiple mechanisms. The original plan was to use a 6 by 6 matrix, but that wouldn’t fit into the laser cutter, so it ended up with 24 mechanisms in a 5 by 6 array. All of those are driven by 2 AAA batteries, and the mechanisms are efficient enough that it survived a full day of button flipping before it began to run out of juice.

Continue reading “Array Of Useless Machines Is Useless” →