A red hot crucible is held with metal tongs above a white plaster mold. The mold is held in a bright pink silicone sleve atop a metal pan on a wooden workbench. Red cheese wax holds the sleeve to a metal funnel connected to a vacuum cleaner.

Lost Print Vacuum Casting In A Microwave

Hacks are rough around the edges by their nature, so we love it when we get updates from makers about how they’ve improved their process. [Denny] from Shake the Future has just provided an update on his microwave casting process.

Sticking metal in a microwave certainly seems like it would be a bad idea at first, but with the right equipment it can work quite nicely to develop a compact foundry. [Denny] walks us through the process start to finish in this video, including how to build the kilns, what materials to use, and how he made several different investment castings using the process. The video might be worth watching just for all the 3D printed tools he’s built to aid in the process — it’s a great example of useful 3D prints to accompany your fleet of little plastic boats.A hand holds a very detailed copper ring. It is inscribed with the words "Open Source Hardware" and the open gear logo associated with open source hardware. It looks kinda like a class ring.

A lot of the magic happens with a one minute on and six minutes off cycle set by a simple plug timer. This allows a more gradual ramp to burn out the PLA or resin than running the microwave at full blast which can cause some issues with the kiln, although nothing catastrophic as demonstrated. Vacuum is applied to the mold with a silicone sleeve cut from a swimming cap while pouring the molten metal into the mold to draw the metal into the cavities and reduce imperfections.

We appreciate the shout out to respirators while casting or cutting the ceramic fiber mat. Given boric acid’s effects, [PDF] you might want to use safety equipment when handling it as well or just use water as that seems like a valid option.

If you want to see where he started check out this earlier version of the microwave kiln and how he used it to make an aluminum pencil.

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Slab Casting – A New Way To Combine 3D Printing And Ceramics

Slip casting can be messy both in processing and in making the original plaster mold. What if there was a better way, thanks to 3D printing?

[Allie Katz] has developed a new technique using 3D printed slab molds to make ceramics. By combining the ability of 3D printing to make intricate designs and the formability of clay, they have found a way to make reproducible clay objects without all that tedious mucking about with liquid clay.

[Katz] takes us through a quick “Mould Making 101” before showing how the slab casting press molds were made. Starting with a positive CAD design, the molds were designed to eliminate undercuts and allow for air infiltration since a plastic mold can’t suck the water out of the clay like a plaster one would. Some cookie clay cutters were also designed to help with the trickier bits of geometry. Once everything was printed, the molds were coated with cornstarch and clay was pressed in. After removal, any final details like handles can be added and the pieces are then fired as normal.

If you’d like to see some more 3D printing mixed up with ceramics, check out 3D printing glass with a laser, reliable ceramic slurry printing, or this TPU-based approach.

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Teletext In Ireland, Another Broadcasting Leftover Bites The Dust

Over the years we’ve reported on the passing of a few of the broadcasting technologies of yesteryear, such as analogue TV in America, or AM radio in Europe. Now it’s the turn of an early digital contender, as one of the few remaining holdouts of old-style teletext is to shut down its service. The Irish broadcaster RTÉ is to turn off its teletext service Aertel, which has been live in some form continuously since 1986.

Like all European countries, Ireland has had only digital TV for quite a few years now. The linked RTÉ piece implies that the Aertel service has been carried as the old-style data in the frame blanking period even when part of a digital multiplex rather than the newer digital teletext system, so we’d be really grateful if some of our Irish readers could flick on their TVs and confirm that.

In an internet-connected world it seems quaint that a limited set of curated pages could once have been such a big deal, but it’s easy to forget that for many the teletext system provided their first ever taste of online information. As it shuffles away almost unnoticed we won’t miss counting through the page numbers cycling by in the top corner as we waited for our page to load, but it’s worth marking its final passing from one of the few places it could still be found.

Teletext does pop up in a few projects here, most recently as the display engine for a game of DOOM.

Nuke Your Own Uranium Glass Castings In The Microwave

Fair warning: if you’re going to try to mold uranium glass in a microwave kiln, you might want to not later use the oven for preparing food. Just a thought.

A little spicy…

Granted, uranium glass isn’t as dangerous as it might sound. Especially considering its creepy green glow, which almost seems to be somehow self-powered. The uranium glass used by [gigabecquerel] for this project is only about 1% U3O8, and isn’t really that radioactive. But radioactive or not, melting glass inside a microwave can be problematic, and appropriate precautions should be taken. This would include making the raw material for the project, called frit, which was accomplished by smacking a few bits of uranium glass with a hammer. We’d recommend a respirator and some good ventilation for this step.

The powdered uranium glass then goes into a graphite-coated plaster mold, which was made from a silicone mold, which in turn came from a 3D print. The charged mold then goes into a microwave kiln, which is essentially an insulating chamber that contains a silicon carbide crucible inside a standard microwave oven. Although it seems like [gigabecquerel] used a commercially available kiln, we recently saw a DIY metal-melting microwave forge that would probably do the trick.

The actual casting process is pretty simple — it’s really just ten minutes in the microwave on high until the frit gets hot enough to liquefy and flow into the mold. The results were pretty good; the glass medallion picked up the detail in the mold, but also the crack that developed in the plaster. [gigabecquerel] thinks that a mold milled from solid graphite would work better, but he doesn’t have the facilities for that. If anyone tries this out, we’d love to hear about it.

Casting Custom Resin Buttons For The Steam Deck

If you play games on multiple consoles, you’re probably familiar with the occasional bout of uncertainty that comes with each system’s unique button arrangement. They’re all more or less in the same physical location, but each system calls them something different. Depending on who’s controller you’re holding, the same button could be X, A, or B. We won’t even get started on colors.

Overhearing her partner wish the buttons on his Steam Deck matched the color scheme of the Xbox, [Gina Häußge] (of OctoPrint fame) decided to secretly create a set of bespoke buttons for the portable system. There was only one problem…she had no experience with the silicone molding process or epoxy resins which would be required for such an operation.

Toothpicks were used to make channels in the mold.

Luckily we have the Internet, and after researching similar projects that focused on other consoles, [Gina] felt confident enough to take apart Steam’s handheld and extract the original plastic buttons. These went into a clever 3D printed mold box, which was small enough to put into a food vacuum container for degassing purposes. The shape of the buttons necessitated a two-piece mold, into which [Gina] embedded two channels: one to inject the resin, and another that would let air escape.

The red, green, blue, and yellow resins were then loaded into four separate syringes and forced into the mold. It’s critically important to get the orientation right here, as each button has a slightly different shape. It sounds like [Gina] might have mixed up which color each button was supposed to be during an earlier attempt, so for the final run she made a little diagram to keep track. After 24 hours she was able to peel the mold apart and get a look at the perfectly-formed buttons, but it took 72 hours before they were really cured enough to move on to the next step.

[Gina] applied the legends with a sheet of rub-on lettering, which we imagine must have been quite tricky to get lined up perfectly. Since the letters would get worn off after a few intense gaming sessions without protection, she finally sealed the surface of each button by brushing on a thin layer of UV resin and curing it with a flashlight of the appropriate wavelength.

There are a fair number of steps involved, and a fair bit of up-front cost to get all the materials together, but there’s no denying the final result looks phenomenal. Especially for a first attempt. We wouldn’t be surprised if the next time somebody wants to head down this particular path, it’s [Gina]’s post that guides them on their way.

Translating And Broadcasting Spoken Morse Code

When the first radios and telegraph lines were put into service, essentially the only way to communicate was to use Morse code. The first transmitters had extremely inefficient designs by today’s standards, so this was more a practical limitation than a choice. As the technology evolved there became less and less reason to use Morse to communicate, but plenty of amateur radio operators still use this mode including [Kevin] aka [KB9RLW] who has built a circuit which can translate spoken Morse code into a broadcasted Morse radio signal.

The circuit works by feeding the signal from a microphone into an Arduino. The Arduino listens for a certain threshold and keys the radio when it detects a word being spoken. Radio operators use the words “dit” and “dah” for dots and dashes respectively, and the Arduino isn’t really translating the words so much as it is sending a signal for the duration of however long each word takes to say. The software for the Arduino is provided on the project’s GitHub page as well, and uses a number of approaches to make sure the keyed signal is as clean as possible.

[Kevin] mentions that this device could be used by anyone who wishes to operate a radio in this mode who might have difficulty using a traditional Morse key and who doesn’t want to retrain their brain to use other available equipment like a puff straw or a foot key. The circuit is remarkably straightforward for what it does, and in the video below it seems [Kevin] is having a blast using it. If you’re still looking to learn to “speak” Morse code, though, take a look at this guide which goes into detail about it.

Thanks to [Dragan] for the tip!

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Casting Metal With A Microwave And Vacuum Cleaner

Metalworking might conjure images of large furnaces powered by coal, wood, or electricity, with molten metal sloshing around and visible in its crucible. But metalworking from home doesn’t need to use anything more fancy than a microwave, at least according to [Denny] a.k.a. [Shake the Future]. He has a number of metalworking tools designed to melt metal using a microwave, and in this video he uses them to make a usable aluminum pencil with a graphite core.

Before getting to the microwave kiln, the pencil mold needs to be prepared. A 3D-printed pencil is first created with the graphite core, and then [Denny] uses a plaster of Paris mixture to create the mold for the pencil. The 3D printed plastic is left inside the mold and placed in the first microwave kiln, which is turned on just enough to melt the plastic out of the mold, leaving behind the graphite core. From there a second kiln goes into the microwave to melt the aluminum.

Once the molten aluminum is ready, it is removed from the kiln and poured in the still-warm pencil mold. This is where [Denny] has another trick up his sleeve. He’s using a household vacuum cleaner to suck the metal into place before it cools, creating a rudimentary but effective vacuum forming machine. The result is a working pencil, at least after he wears down a few razor blades attempting to sharpen the metal pencil. For more information about how [Denny] makes these microwave kilns, take a look at some of his earlier projects.

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