If you’ve ever wanted to forge, cast, or smelt metal, this project is right up your alley. It’s a 30 kVA induction heater built by [bwang] over on Instructables. It gets hot enough to melt and forge steel, iron, and aluminum.

An induction heater operates by surrounding the object to be heated with a coil carrying high frequency AC current. Basically, the entire setup acts like a huge transformer with a shorted secondary. To get these currents into a workpiece, [bwang] used a TL494 PWM controller as an oscillator. The output of the TL494 is filtered and amplified a few times to generate a huge amount of AC current.

Larger versions of [bwang]’s induction heater are found in foundries and forges all across the land; even though this small version sucks down 50 A out of a dryer or stove outlet, induction heating is very efficient. We’re actually wondering why we don’t see many home blacksmiths using induction heating, so we’ll leave that for our readers to discuss in the comments.

[sessions] reminded us of this induction heater from a few years ago. A little smaller, but still usable.

Every filament-based 3D printer you’ll find today heats plastic with resistive heaters – either heater cartridges or big ‘ol power resistors. It’s efficient, but that will only get you so far. Given these heaters can suck down only so many Watts, they can only heat up so fast. That’s a problem, and if you’re trying to make a fast printer, it’s also a limitation.

Instead of dumping 12 or 24 VDC into a resistive heater, induction heaters passes high-frequency AC through a wire that’s inductively coupled to a core. It’s also very efficient, but it’s also very fast. No high-temperature insulation is required, and if it’s designed right, there’s less thermal mass. All great properties for fast heating of plastic.

A few years ago, [SB] over on the RepRap blog designed an induction heater for a Master’s project. The hot end was a normal brass nozzle attached to a mild steel sleeve. A laminated core was attached to the hot end, and an induction coil wrapped around the core. It worked, but there wasn’t any real progress for turning this into a proper nozzle and hot end. It was, after all, just a project.

Finally, after several years, people are squirting plastic out of an induction heated nozzle. [Z], or [Bulent Unalmis], posted a project to the RepRap forums where he is extruding plastic that has been heated with an induction heater. It’s a direct drive system, and mechanically, it’s a simpler system than the fancy hot ends we’re using now.

Electronically, it’s much more complex. While the electronics for a resistive heater are just a beefy power supply and a MOSFET, [Z] is using 160 kHz AC at 30 V. That’s a much more difficult circuit to stuff on a printer controller board.

This could be viewed as just a way of getting around the common 24V limitation of common controller boards; shove more power into a resistor, and it’s going to heat faster. This may not be the answer to hot ends that heat up quicker, but at the very least it’s a very neat project, and something we’d like to see more of.

You can see [Z]’s video demo of his inductive hot end below. Thanks [Matt] for the tip.

[Proto G] built a small, desktop induction heater that is capable of making small castings, melting small amounts of metal, and functioning as one of the best solder pots we’ve ever seen.

The induction heater is built from a custom Zero Voltage Switching (ZVS) driver and powered by a small 48V, 1000W power supply. While this makes for an exceptionally small induction heater, it’s still very capable. In the video below, it only takes a few seconds to heat a screwdriver up to a temperature that will melt solder.

While an induction heating machine is essentially useless for irons unless you have a few antique, unpowered, blowtorch-powered soldering irons, it does make for a great solder pot. [Proto G] replaced the working coil in his induction heater with litz wire. The actual solder pot is made out of steel conduit wrapped with aerogel-infused fiberglass insulation. Compared to his old solder pot, this machine heats up instantly, and is more than capable of wetting a few wire connections.

The future plan for this inductive heater is to make a few more attachments for different metals, and a [Proto G] has a few aerogel blankets he could use to make some small metal castings.

Ever want to try your hand at black smithing? Building a forge is expensive and tricky — especially if you live in an apartment! But we’re all tech nerds here — it’s way cooler to use induction heating to heat up your metal for forging. Fire is for cavemen! [Josh Campbell] is working on a kit to bring induction heating to the masses — he calls it the Reactor Forge.

The kit hasn’t launched yet, but you can follow his progress on his GitHub. Induction heating works by magnetically inducing current into the metal, where resistance turns the current into heat without physical contact. The Reactor Forge [Josh] has built runs off of a 220V circuit, and in the following demonstration, heats up a 6″ section of 1/2″ steel bar.

When the bar is cold, the induction heater draws about 1500 W — but once it starts to heat up, it draws more and more, topping out at a whopping 6500 W once heated up.

As far as induction heaters go, this project looks pretty slick. But we love this old induction heater we covered a few years back. It uses a KFC chicken bucket as the concrete mold for the furnace chamber!

[Thanks for the tip Mark!]

[Kasyan TV] shows us how to make a really simple DIY induction soldering iron complete with DIY soldering tips.

This is a pretty cool project. Most of us are used to temperature controlled ceramic heating elements, but there are other ways to get those irons up to temperature. Using scraps from older, presumably broken, soldering irons and some pieces of copper and iron along with a thermocouple for temperature management, [Kasyan TV] manages to throw together an Inductively heated soldering iron. To insulate the coil from the iron they use Kapton tape. The video goes on to show how to make your own induction iron, although missing is a power supply. We are sure a quick eBay search for an induction heater module should bring up something suitable to power the iron, or you could just wait and watch the their next video that will go over power supplies. The soldering tips are simply made from thick copper wire sculpted into the correct shape.

There are advantages to using a soldering iron like this, for example they are pretty durable and will take a knock or two, Our concern is that magnetically sensitive parts may not be happy, and the iron might destroy what you are trying to build. Either way we’ve put the video below the break, so take a look.

Hackaday has featured a few different DIY soldering irons and some pretty cool DIY Soldering Stations over the years. What is your soldering iron of choice and why?

Preparing food is the fourth most energy-intensive activity in a household. While there has been a lot of effort on the first three — space heating, water heating, and electrical appliances — most houses still use stoves and ovens that are not too dissimilar to those from half a century ago.

More recent technologies that make cooking more efficient and pleasant have been developed, such as induction heating. Other well-known and common appliances are secretly power savers: microwaves and electric kettles. In addition, pressure cookers enable the shortening of cooking times, and for those who like dishes that take hours to simmer, vacuum-insulated pans can be a real energy-saver.

Not Just About Energy

One aspect that is often neglected in discussions about saving energy is that many more power-efficient methods are simply more convenient and require less cleaning. Speaking as someone who has had to do things like heating milk on a gas stove, using a microwave saves one from having to scrub the pan clean afterwards. Similarly, an electric kettle beats a stovetop tea kettle any day of the week for its speed and convenience.

Not having to keep an eye on whatever will be boiling soon, and never coming upon a boiled over pan of milk is convenient, and an induction stove is very easy to clean as it’s only ever indirectly heated. Heating something up in a microwave directly on the plate is much more convenient than having to clean a dirty a frying pan afterwards.

All of which is to say that not only are many of these approaches energy-efficient, they’re also excellent for lazy people and everyone else who doesn’t want to spend more time on cooking, boiling, and cleaning each day than strictly necessary.

Running The Numbers

In an article by the BBC on why you should stop using your oven, they cite a study by Frankowska et al. (2020), in which the energy consumption of a few different heating methods are compared. Of these two the boiling of water and reheating of a casserole are good examples:

Boiling water (1 cup of tea)

• 0.05 kWh, 4 minutes in a microwave
• 0.07 kWh, 2 minutes in an electric kettle
• 0.14 kWh, 2 minutes in covered pan or kettle on induction stove
• 0.18 kWh, 5 minutes on standard electric stove

Reheating casserole

• 0.11 kWh, 8 minutes in microwave
• 0.35 kWh, 5 minutes on induction stove
• 0.43 kWh, 12 minutes on standard electric stove
• 2.27 kWh, 45 minutes in the oven

Porridge

• 0.07 kWh, 5 minutes in microwave
• 0.35 kWh, 5 minutes on induction stove
• 0.36 kWh, 10 minutes on standard electric stove

Of note here is of course that when an electric kettle is mentioned, it refers to a European-style electric kettle. These tend to be rated for 2 kW – 3 kW, which enables them to boil water very quickly. So it’s no surprise that they’re boiling water twice as fast as a microwave with a 1,000 W setting. Depending on the use case, more energy input can make things boil and cook significantly faster, while saving energy and one’s time as well in the process. Which leads us to the other options, such as optimized heat transfers and lids.

Putting A Lid On It

A general idea behind efficient cooking is to get as much of the energy into the item that is being heated, without having it be converted to waste heat and escape into the environment. This is an obvious issue with gas stoves: a significant part of the heat produced by the combustion flows out the side and never heats up the cookware.

With an electric stove where the pan is placed directly on the surface that is being heated by the heating element, there is significantly less heat escaping into the environment, though here we still have the inefficiencies of heating the stove surface, transferring that heat into the pan’s material and from there into the contents of the pan.

This is where the idea behind induction stoves is so very attractive and simple: rather than putting the cookware on something hot, with induction an induction coil induces inductive coupling in the ferromagnetic material of the cookware, which causes it to heat up. This way the cookware itself becomes the hot surface that heats the food, which skips all of the previously mentioned intermediate steps, and thus losses.

This then leaves the other loss of heat: from the pan contents itself, which is where lids come in. By turning the pan into a closed vessel, the only effective way for heat to escape from the pan is through heating up the pan and lid and radiating into the environment that way. As a simple comparison can show here, the use of a pan lid can significantly shorten the amount of time needed to boil water, and the power needed to keep the contents on temperature.

From this we can thus deduce that an even more efficient way to cook on a stove would be if we could prevent the heat from radiating through the pan’s material. This is where double-walled cookware comes into play, with some level of vacuum between both walls much like in a thermos, which are great at keeping drinks hot or cold for long periods. In these pans, food stays warm for hours even without externally applied heat.

Putting On Pressure

The only major disadvantage of double-walled cookware (like Kuhn Rikon) is that they are very pricey, with a simple pan often costing upwards of a few hundred dollars. Outside of finding a used one for cheap, this is probably the kind of expense that’d be hard to justify. So on the other end of the budget scale, consider pressure cookers, which are somewhat like the extreme version of pan lids.

The basic idea behind a pressure cooker is that the high pressure inhibits boiling, so the cooking temperature can be increased above 100 °C. This significantly shortens the time it takes to cook the food, although it obviously is limited to damp cooking because of the steam that enables the increased pressure levels.

Unlike vacuum-insulated cookware, pressure cookers can be found for relatively cheap, and provide energy and time savings. Perhaps the biggest disadvantages are not being able to look inside the pan while cooking – requiring cooking times to be determined beforehand – and them being unsuitable for cooking noodles, pasta and similar foods which would expand too much.

Keeping It Fun

As noted earlier, the best part of saving energy is when it also makes life easier at the same time. The good news is thus that using the microwave to (re)heat food is both easy and efficient, and an easy to clean induction stove more efficient than a gas or electric stove. This was fortunately also my finding when switching from a ceramic stove to an induction one. While the former required some scrubbing and scraping after ‘accidents’, the latter just takes a simple wipe-down with a moist kitchen towel.

I’m also fortunate enough to living in a country where I’m able to plug my 3 kW electric kettle into a kitchen outlet and efficiently boil water that way, and was able to get a 3.5 kW induction stove that I could plug into an outlet next to the kettle’s. With it being obviously so much more efficient to use electricity to cook and heat food, perhaps having a kitchen fully wired for 240 VAC is the winning move for fun, efficient cooking?

With how much of a personal topic cooking is, please feel free to sound off in the comments about your own experiences and approaches when it comes to making cooking more fun and efficient.

Have you ever wondered how induction cooking works? A rotating magnetic field — electrically or mechanically — induces eddy currents in aluminum and that generates heat. When [3D Sage] learned this, he decided to try to 3D print some mechanical rigs to spin magnets so he could try cooking with them.

We doubt at all that this is practical, but we have to admit it is fun and there are some pretty impressive 3D prints in the video, too. The cook surface, by the way, is tiny, so you won’t be prepping a holiday meal on it. But there’s something super charming about the tiny breakfast on a plate produced by a printed magnetic “stove.” We would be interested to know how much power this setup consumed and how much heat was produced compared to, say, just using a big resistor to heat things up.

We’ve heard that induction heating is efficient, but this setup is a bit unconventional. If cooking things isn’t your bag, you can use induction for soldering, too.