DIY Reflow Oven is Heavily Documented

[DJ Legion] decided he wanted a reflow oven so he bought a toaster oven and an assortment of parts including a solid state relay, a Teensy, a display, and a thermocouple. What makes this a different project is the amount of video documentation. The four videos below encompass about 50 minutes of information and he’s promising more to come.

We haven’t found his software — probably because he’s still working on it, but we’re watching his GitHub page expectantly. We really liked the 3D printed faceplate that integrated the controller into the oven. It almost looks like a commercial unit. The use of the woodgrain paper over the 3D printed parts was a nice touch.

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Is Baking a Raspberry Pi the Recipe for Magic Smoke?

No, Hackaday hasn’t become a baking blog. We’re just here to give you a bit of advice: if [MickMake] ever offers you one of his fresh-baked Pis, proceed with caution. While we have no doubt that there will be some interesting smells wafting out of his kitchen, these aren’t the tasty pies you’re looking for. There’s no delicious home-baked treat when that timer dings, just a handful of Raspberry Pis that have had an exceptionally hard day.

To properly explain the odd sight of some Raspberry Pis laid out on a cookie sheet, we need to take a step back. [MickMake] originally set out to see how everyone’s favorite Linux SBC would handle the harsh Australian heat, and thought that setting them up on his car’s dashboard would be a suitable torture test. But as luck would have it, a storm rolled in while he was making the video which brought temperatures down to a “cool” 30 C (86 F); basically jacket weather at the bottom of the world. So naturally, he decided to put them in his oven instead.

Placed on an insulating sheet and with a thermocouple between them to get an accurate idea of the temperature they were experiencing, an original Pi, a Pi 2, and a pair of Pi 3s were sent on the ride of their lives. In addition to monitoring them over the network, he also added a “heartbeat” LED to each Pi so he’d be able to tell at a glance if any of them had given up the ghost. As if these poor little Pis didn’t have it bad enough already, [MickMake] decided to take things a step farther and run sysbench on them while they took their trip through Hades.

The Pis are actually rated for temperatures up to 85C, and all the participants of the experiment hit that point without any issues. At 87.3 C (~190 F) the original Pi dropped off the network, but its LED was seen bravely blinking on. At 105.7 C (~222 F) it finally breathed its last, followed by the pair of Pi 3s tapping out at 112 C (233 F). The Pi 2 fought on, but it fell right at the 119 C (246 F) mark.

But what about when they cooled off? Somewhat surprisingly, [MickMake] successfully powered all four back up and was unable to find any damage to the Pis, either physically or operationally. Even the SD cards survived, and the Pis popped right back onto the network and were ready for another round of Silicon Chef. Not bad considering they were subjected to temperatures three times higher than the official limit.

Testing electronics in your home oven might seem a bit suspect, and admittedly we’d probably turn down a slice of the next few frozen pizza’s [MickMake] runs through it, but it’s not really so far removed from how proper reliability testing is performed.

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Stove Alarm Keeps The Kitchen Safe

Gas cooktops have several benefits, being able to deliver heat near-instantly, while also being highly responsive when changing temperature. However, there are risks involved with both open flames and the potential of leaving the gas on with the burner unlit. After a couple of close calls, [Bob] developed a simple solution to this safety issue.

The round PCB sits neatly behind the knobs, affixed with double-sided tape.

Most commercial products in this space work by detecting the heat from the cooktop, however this does not help in the case of an unlit burner being left on. [Bob]’s solution was to develop a small round PCB that sits behind the oven knobs. Magnets are placed on the knobs, which hold a reed switch open when the knob is in the off position. When the knob is turned on, the reed switch closes, powering a small microcontroller which beeps at regular intervals to indicate the burner is on.

It’s a tidy solution to a common problem, which could help many people – especially the elderly or the forgetful. It integrates neatly into existing cooktops without requiring major modification, and [Bob] has made the plans available if you wish to roll your own.

On the other end of the scale, you might want an alarm on your freezer, too.

A Clay Oven For Perfect Pizza Every Time

Perhaps your taste for pizza has never taken you beyond your local fast-food chain or a frozen pizza from the supermarket, but there are some people for whom only the most authentic will do. A wood-fired clay oven and nothing less is their pre-requisite, and lesser methods of pizza preparation simply aren’t good enough.

[Jan] is one of these pizza perfectionists, and his wood-fired oven is an interesting one because it eschews the traditional dome for a cylinder. His very detailed write-up gives us an interesting insight into its construction. He’s taken the bottom half of an oil drum as his base, and built and fired the clay oven itself around a wooden former. We see his early attempts at a former which distorted under the weight of clay, and we hear about how the clay required reinforcement with chicken wire and straw. Finally, we see the structure being dried out, before an impressive display when firing for the first time. The oven receives a coat of Rockwool insulation but [Jan] has a way to go to learn the oven’s characteristics. Still, this is an oven that will last to refine the perfect morsel given a bit of time.

We like the cylindrical design as an alternative to domed ovens, which can be a bit tricky to build. An oven may be a bit low-tech compared to some of Hackaday’s usual fare, but they can be no less difficult to get right. We’re no stranger to novel flame-based cookery, perhaps you might like to also take a look at this rocket grill.

DIY Tube Oven Brings the Heat to Homebrew Semiconductor Fab

Specialized processes require specialized tools and instruments, and processes don’t get much more specialized than the making of semiconductors. There’s a huge industry devoted to making the equipment needed for semiconductor fabrication plants, but most of it is fabulously expensive and out of reach to the home gamer. Besides, where’s the fun in buying when you can build your own fab lab stuff, like this DIY tube oven?

A tube oven isn’t much more complicated than it sounds — it’s just a tube that gets hot. Really, really hot — [Nixie] is shooting for 1,200 °C. Not just any materials will do for such an oven, of course, and this one is built out of blocks of fused alumina ceramic. The cavity for the tube was machined with a hole saw and a homebrew jig that keeps everything aligned; at first we wondered why he didn’t use his lathe, but then we realized that chucking a brittle block of ceramic would probably not end well. A smaller hole saw was used to make trenches for the Kanthal heating element and the whole thing was put in a custom stainless enclosure. A second post covers the control electronics and test runs up to 1,000°C, which ends up looking a little like the Eye of Sauron.

We’ve been following [Nixie]’s home semiconductor fab buildout for a while now, starting with a sputtering rig for thin-film deposition. It’s been interesting to watch the progress, and we’re eager to see where this all leads.

A Different Use For Microwave Oven: Melting Aluminum

Microwave ovens are a treasure trove of useful parts: transformers, an HV capacitor, a piezo speaker, and a high torque motor, to name just a few. In a new twist, [Rulof Maker] strips all that out and uses just the metal case to make a furnace for melting aluminum, copper and bronze.

His heat source is a quartet of 110 volt, 450 watt quartz heating elements which he mounts inside in the back. To reduce heat loss, he lines the walls with ceramic fiber insulation. Unfortunately, that includes covering the inside of the window, so there’s no pressing your nose against the glass while you watch the aluminum pieces turn to liquid. If you’re going to try making one of these yourself then you may want to consider adding a fuse.

It does the job though. In around nine minutes he melts enough scrap aluminum in a stainless steel bowl to pour into a mold for a test piece. But don’t take our word for it, see for yourself in the video below.

If want more information on what useful parts are inside then check out this primer. Or you can leave the parts in and use the oven as is for melting lead, but keep a fire extinguisher handy.

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Reflowduino: Put That Toaster Oven To Good Use

There are few scenes in life more moving than the moment the solder paste melts as the component slides smoothly into place. We’re willing to bet the only reason you don’t have a reflow oven is the cost. Why wouldn’t you want one? Fortunately, the vastly cheaper DIY route has become a whole lot easier since the birth of the Reflowduino – an open source controller for reflow ovens.

This Hackaday Prize entry by [Timothy Woo] provides a super quick way to create your own reflow setup, using any cheap means of heating you have lying around. [Tim] uses a toaster oven he paid $21 for, but anything with a suitable thermal mass will do. The hardware of the Reflowduino is all open source and has been very well documented – both on the main page and over on the project’s GitHub.

The board itself is built around the ATMega32u4 and sports an integrated MAX31855 thermocouple interface (for the all-important PID control), LiPo battery charging, a buzzer for alerting you when input is needed, and Bluetooth. Why Bluetooth? An Android app has been developed for easy control of the Reflowduino, and will even graph the temperature profile.

When it comes to controlling the toaster oven/miscellaneous heat source, a “sidekick” board is available, with a solid state relay hooked up to a mains plug. This makes it a breeze to setup any mains appliance for Arduino control.

We actually covered the Reflowduino last year, but since then [Tim] has also created the Reflowduino32 – a backpack for the DOIT ESP32 dev board. There’s also an Indiegogo campaign now, and some new software as well.

If a toaster oven still doesn’t feel hacky enough for you, we’ve got reflowing with hair straighteners, and even car headlights.