Reactor Forge Promises Induction Heating For All

April 5, 2016 by 60 Comments

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.

Continue reading “Reactor Forge Promises Induction Heating For All” →

What Can We Learn From A Cheap Induction Cooktop?

February 19, 2016 by 16 Comments

Sometimes tearing down a cheap appliance is more interesting that tearing down an expensive one. A lot of the best engineering happens when cost is an issue. You may not solve the problem well, but you can solve it well enough for a discount shelf.

[openschemes] purchased a 1.8kW induction hot plate at a low price off Amazon. The reasons for the discount soon became apparent. The worst of which was a fully intolerable amount of high frequency switching noise. Wanting to know how it worked, he took it apart.

After he had it apart on his desk, he deciphered the circuit, and wrote about it clearly. As usual with extremely cheap electronics, some clever hacks were employed. The single micro-controller was used for monitoring, and generated a PWM signal that was instantly converted to DC through some filters. All the switching was done the old fashioned way, which explained why the hotplate seemed so brainless to [openschemes] when he first turned it on.

Lastly, he did some work on manually controlling the cooktop for whatever reason. The good news? He managed to figure out how to control it. Unfortunately he also destroyed his unit in the process, via a misapplication of 1200 volts. A fitting end, and we learned a lot!

Thanks [David Balfour] for the tip!

A Small, 1000W Induction Heater

October 23, 2015 by 100 Comments

[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.

Continue reading “A Small, 1000W Induction Heater” →

3D Printering: Induction Heating

March 15, 2015 by 13 Comments

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.

Continue reading “3D Printering: Induction Heating” →

Kentucky-Fried Induction Furnace

December 2, 2014 by 34 Comments

[John] and [Matthew] built an induction-heater based furnace and used it to make tasty molten aluminum cupcakes in the kitchen. Why induction heating? Because it’s energy efficient and doesn’t make smoke like a fuel-based furnace. Why melt aluminum in the kitchen? We’re guessing they did it just because they could. And of course a video, below the break, documents their first pour.

Now don’t be mislead by the partly low-tech approach being taken here. Despite being cast in a large KFC bucket, the mini-foundry is well put together, and the writeup of exactly how it was built is appreciated. The DIY induction heater is also serious business, and it’s being monitored for temperature and airflow across the case’s heatsinks. This is a darn good thing, because the combination of high voltage and high heat demands a bit of respect.

Anyway, we spent quite a while digging through [John]’s website. There’s a lot of good information to be had if you’re interested in induction heaters. Nonetheless, we’ll be doing our metal casting in the back yard.

Continue reading “Kentucky-Fried Induction Furnace” →

LEGO® My Single-Phase Induction Motor

March 30, 2014 by 5 Comments

[Diato556] made a really cool single-phase induction motor with parts mounted on Duplo blocks. He has posted an Instructable where he uses these modular parts to  demonstrate the motor and the principles of induction as described after the jump.

 

Continue reading “LEGO® My Single-Phase Induction Motor” →

Repairing And Adding Bluetooth Control To An Induction Cooker

December 2, 2013 by 23 Comments

When his 6 years old induction cooker recently broke, [Johannes] decided to open it in an attempt to give it another life. Not only did he succeed, but he also added Bluetooth connectivity to the cooker. The repair part was actually pretty straight forward, as in most cases the IGBTs and rectifiers are the first components to break due to stress imposed on them. Following advice from a Swedish forum, [Johannes] just had to measure the resistance of these components to discover that the broken ones were behaving like open circuits.

He then started to reverse engineer the boards present in the cooker, more particularly the link between the ‘keyboards’ and the main microcontroller (an ATMEGA32L) in charge of commanding the power boards. With a Bus Pirate, [Johannes] had a look at the UART protocol that was used but it seems it was a bit too complex. He then opted for an IOIO and a few transistors to emulate key presses, allowing him to use his phone to control the cooker (via USB or BT). While he was at it, he even added a temperature sensor.