Simple Induction Heater Helps With Homebrew Shrink-Fitting

October 26, 2020 by 14 Comments

Machinists have a lot of neat shop tricks, but one especially interesting one is shrink-fitting tools. Shrink-fitting achieves an interference fit between tool and holder by creating a temperature difference between the two before assembly. Once everything returns to temperature, the two parts may as well be welded together.

The easiest way to shrink-fit machine tooling is with induction heating, and commercial rigs exist for doing the job. But [Roetz 4.0] decided to build his own shrink-fitting heater, and the results are pretty impressive. The induction heater itself is very simple — a 48 volt, 20 amp power supply, an off-the-shelf zero-voltage switching (ZVS) driver, and a heavy copper coil. When the coil is powered up, any metal within is quickly and evenly heated by virtue of the strong magnetic flux in the coil.

To use the shrinker, [Roetz 4.0] starts with a scrupulously clean tool holder, bored slightly undersized for the desired tool. Inside the coil, the steel tool holder quickly heats to a lovely deep brown color, meaning it has gotten up to the requisite 250-300°C. The tool is quickly dropped into the now-expanded bore, which quickly shrinks back around it. The advantage of this method over a collet or a chuck is clear in the video below: practically zero runout, and the tool is easily released after another run through the heater.

You say you’ve got no need for shrink-fitting tools? How about stuck bolts? Induction heaters work great there too.

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How To Get Into Cars: Forced Induction

April 16, 2020 by 43 Comments

For those addicted to automotive thrills, there’s always an underlying lust for more power. For those chasing a bigger number, forced induction is one of the most effective ways to achieve it. In addition to more grunt, you get a whole bunch of fun new noises, too.  For those with a naturally aspirated car, here’s how you go about converting to forced induction.

Superchargers and Turbos

When we talk about forced induction, we’re talking about forcing more air into the engine under pressure. With more air available, it’s possible to fully combust more fuel, creating more power. The two most common ways of doing this are supercharging and turbocharging. We’ll be using the common automotive vernacular here, so those eager to bicker about terminology from the early 20th century aircraft industry best do it in the comments. Continue reading “How To Get Into Cars: Forced Induction” →

Set Your Nuts (and Bolts) Free With This Induction Heater

May 22, 2019 by 36 Comments

[Amon] built an induction heater to break stuck bolts loose. If you work on cars, machines, or anything big and metal, sooner or later you’re going to run into stuck nuts and bolts. Getting them unstuck usually involves penetrating oil, heat from a torch, and cheater bars. Heat usually works well, as heating the bolt makes the metal expand, helping it to break free. Torches aren’t exactly precision instruments though, and things can get interesting using one in tight spaces.

Fire isn’t the only way to heat a bolt through. Electricity can do the job as well. But why use a heating coil when you can grab an induction heater. Mechanics have had induction heaters in their toolboxes now for a few years, under names such as Bolt Buster or Mini Ductor. These devices cost several hundred dollars. However, you can purchase a 1000 watt induction heater from the usual sources for around $30. These are open frame Zero Voltage Switching (ZVS) power supplies, with uninsulated copper coils.

[Amon] bought one of these induction heaters, along with a beefy 24V, 40 amp switch mode supply to power it. He built the two into a plastic enclosure. A relay energizes the induction heater, so it isn’t always running. The key to this build is the handle. Rather than mount the induction coil directly on the supply, [Amon] ran two extension wires to a 3d printed gun style handle. This keeps the bulky part of the heater away from the work. The copper tube coil was re-shaped to better work with the gun. Some fiberglass sleeve keeps everything insulated, even at extreme temperatures.

The result is a very useful heater, ready to bust loose some bolts. We’ve seen homebuilt ZVS supplies powering induction coils before. It will be interesting to see how well these commercial units hold up.

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Inventing The Induction Motor

September 21, 2017 by 36 Comments

When you think of who invented the induction motor, Nikola Tesla and Galileo Ferraris should come to mind. Though that could be a case of the squeaky wheel being the one that gets the grease. Those two were the ones who fought it out just when the infrastructure for these motors was being developed. Then again, Tesla played a huge part in inventing much of the technology behind that infrastructure.

Although they claimed to have invented it independently, nothing’s ever invented in a vacuum, and there was an interesting progression of both little guys and giants that came before them; Charles Babbage was surprisingly one of those giants. So let’s start at the beginning, and work our way to Tesla and Ferraris.

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DIY Induction Soldering Iron

June 1, 2017 by 36 Comments

[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?

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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.

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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!