This week on Maker Update: a robot to knock over your coffee, a plastic trombone powered by CircuitPython, powering your workshop with RFID, giant foam pumpkins, plastic restoration, slushcasting, and searching for hidden gems on AliExpress.

++Show Notes [Maker Update Ep.303]++

-=Project of the Week=-

3d Printed 6-Axis Robot Arm by 3d Printed Life
https://www.youtube.com/watch?v=e3TNaIyTAnY

-=More Projects=-

Trombone Champ Controller by Liz Clark
https://learn.adafruit.com/circuitpython-trombone-champ-controller

RFID Workshop Safety Switch by Taste_The_Code
https://www.instructables.com/Workshop-Safety-Switch-With-RFID/

Automated Slide Digitizer by rbwood53
https://www.instructables.com/Automated-35mm-Slide-Digitizer/

Oversized Foam Jack-O-Lantern by Haunted Spider
https://www.instructables.com/Oversized-Foam-Jack-o-Lantern/

-=Tips & Tools=-

Hidden Gems on AliExpress by Great Scott
https://www.youtube.com/watch?v=fUdlfc1nJcY

Cyberpunk 2077 Techgogs by smiteorflight
https://www.thingiverse.com/thing:5033163

Clear Plastic Restoration by Adam Savage
https://www.youtube.com/watch?v=-Jk1MrTpJOk

Slush Casting Guide by Robert Tolone
https://www.youtube.com/watch?v=mVAzfzzht1g

-=Digi-Key Spotlight=-

How do Fiber Optic Cables Work?
https://www.youtube.com/watch?v=VmhEoK7OUtU

-=Transcript=-

This week on Maker Update A robot to knock over your coffee, A plastic Trombone powered by CircuitPython, Powering your workshop with RFID, Giant Foam Pumpkins, Plastic Restoration, Slushcasting, and searching for hidden gems on AliExpress.

Hello and welcome back to Masker Update. I’m Tyler Winegarner, I hope you’re all doing great. I don’t know about you, but around here, it seems like Summer just got up and left in a big hurry. It’s nice to feel some crisper weather again, but it’s also a great reminder that halloween is right around the corner. We’ve got some spooky projects for you later on in the show if you need some ideas. But in the meantime, let’s check out the project of the week.

Do you remember a good while back when we featured a 3d printed harmonic drive on this show? It was definitely one of those projects that opened my eyes to some new engineering possibilities, even though I didn’t really realize its practical applications. Well it turns out, one of its practical applications is this:

3dPrintedLife took their harmonic drive, added some refinements, and used them to create a fairly compact but strong 6-axis 3d printed robot arm, with the intent of it being able to move their camera in space. They have a few constraints in mind as well – of course, it needs to be able to move their camera, so it has comfortably lift a little over a kilogram, and they wanted to come in under a $500 budget.

Along the way there’s a ton of great tips – like using carbon fiber rods to join very large parts together in a way that makes them easier to print and adds strengths while keeping them light. There’s also a good one for adding a stiff interface between shafts and 3d printed parts – if you just pop the top off of one of these GT2 pulleys, you can press it into a 3d printed part with matching teeth and get a reliable no-slip interface.

There’s also a tiny bit about the complex mathematics of inverse kinematics – that’s where you can tell the robot’s end effector to move to a specific point in space, and then the code does all the hard work to tell each motor how far to turn to get there. They stare a little bit into that complex void, and then backed off to a simpler version so they could have a working robot by the end of this video. They also created their own micronized version of the Feather M4, with more robust power management, a smaller footprint, and avoiding some chip shortage issues. Let’s hear it for open hardware.

But by the end, they got what they set out to do. There’s still some stuff to get worked out – like how the wrist joint needs some additional strengthening. And there’s some stutter coming from the harmonic drives – but it’s a long way from just a simple compact gearing mechanism – and it looks great too. If you’re interested in working on this project yourself, they share a github repo with all the necessary code and files.

More Projects! Depending on how much you keep up with ridiculous video game news, you may have heard of Trombone Champ, a game that lets you relive your high school band brass section dreams. Liz Clark and Kattni Rembor from Adafruit teamed up to make this 3d printed custom controller for the game. A slide potentiometer that moves with the 3d printed trombone slide adjusts the pitch of the instrument, and the light-up arcade button on the back lets you toot your way to victory. Circuit Python’s HID emulation makes it easy to interface with your computer as a control device. Maybe a little silly, but hey, custom controls make any music game better, right?

On instructables I found this great workshop safety project by Taste The Code. Its execution is simple enough – An arduino nano reads the input from an RFID tag reader, and depending on the tag presented, triggers a relay. That relay controls a much larger electrical switch called a contactor. A contactor can carry much heavier loads than a relay – enough that he can comfortably run all of his workshop’s electricals through the contactor, effectively cutting off power unless the correct RFID tag is present. Whether you’ve ever wondered how to use software to control high electrical loads or how to work with RFID tags, check this one out.

Also on instructables I found this guide to an automated slide digitizer by rbwood53. This makes use of an old carousel-style slide projector. You remove the lens and the projector lamp, and replace them with this tiny, 3d printed backlit projection screen. A digital camera then photographs the slide image projected onto this screen to digitize the image. An arduino nano living in a control box manages the advancement of the slides, triggering the camera, the whole lot. The best part is, all of the modifications made to the slide projector are reversible, so you don’t need to cannibalize a piece of classic hardware to try this one out.

And finally we have a great tutorial for making this oversized foam Jack-O-Lantern by Haunted Spider. Like with anything this size, you can’t just take the same approach as a normal sized one and just scale it up. Using a collection of styrofoam blocks he got for free from Tractor Supply, he treated the entire thing like a segmented bowl, and then used the offcut wedges to add a little bit more roundness to the vertical surfaces. From there its a whole lot of carving, filling, sealing, vacuuming the lawn, and painting. The wonderful final touch is adding a giant carving knife to the skeleton hand next to it.

Time for some tools and tips, on his channel, Great Scott! has plumbed the depths of Ali Express to try and find some hidden gems that make the long shipping times worth the while. His first hit was a super capacitor power filter, which can be used to reduce low voltage noise commonly associated with amplifiers. There’s also a super efficient lithium battery charger that can be had for just 70 cents, and a handful of drill powered attachments like a jigsaw and mini chainsaw. There’s a few misses too, like this hand-crank generator.

If you’re looking for a kickstart to your halloween costume, check out these 3d printable techgogs from Cyberpunk 2077 by smiteorflight. There’s two versions of this print: one is completely enclosed, and probably better suited for cosplay photoshoots where maybe you don’t need to see. The other has an open front, and is designed so you can cover the opening with neutral density lighting gels. It’ll make it so the inner workings and your eyes won’t be seen from the outside, but you can still get around. Both have recesses for 5mm LEDs and coin cell batteries so they get that signature spider eye look.

Adam Savage is in the process of restoring a Nagra 4-S Audio Recorder. Part of the restoration involves rejuvenating the plastic lid, which has gotten a little cloudy and yellowed with age. First step is to knock down the cloudiness with some plastic polish, which he just works over all of the surfaces by hand – like, literally with his fingers. To take the yellow down, he lets it soak in a solution of 12% hydrogen peroxide overnight. The peroxide still left some of the yellowing behind, but after a second polish using an electric polisher, he’s made a remarkable improvement. Restoration like this is a tricky business and it can easily go bad on you, so its nice to see a thorough video of the process.

Speaking of thorough videos, Robert Tolone has a fantastic video about slush casting. This is a super quick casting process where you rotate the mold by hand to get the resin to coat all the detail areas of your mold while it is curing – but there’s a ton of other tips in here too. This one of brushing on your silicone in areas of the master part where bubbles are likely to form is something I’ve never seen before. I’d also never seen using waxed cardboard as a mold container before. This video is full of great techniques from someone who’s been doing this a while.

For this weeks Digi-key spotlight, they’ve got a quick primer on how fiber optic cables work.I thought I knew most what there was to know about fiber optics, but I had no idea that multi mode cables existed – which are larger diameter caves that can pass multiple signals that operate on different phases. I was also really excited to see these breadboard breakouts for fiber optic cables. Could be fun to use in an upcoming project.

Alright and that is going to do it for this weeks show. I hope you enjoyed it. Be sure to subscribe, give us a thumbs up, Leave us a comment! It’s always great to hear from you all. As always, great big thanks to Digi-Key for making all of this possible, and to you for watching. Take care, we’ll see you soon.