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YOU CAN BUILD THE INDUCTION FURNACE THAT POURS MOLTEN STEEL

An induction furnace that melts brass, steel, and copper, with all the design files published under MIT.

by Hector Jimenez Cruz

FULL CAD BOM FIRMWARE DOCS

WorkshopOpen-hardware

Built withSTM32

difficulty
●●●●●
time
several weekends
license
MIT
repo
repo ACTIVE19 stars

WHAT YOU’LL NEED

Videos
1
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COMPAREE VERDICT

This is documentation of a working induction furnace, not a step-by-step build guide. Hector Jimenez Cruz, publishing as Learning On Demand, built it up through several generations, from about 4 kilowatts on single-phase mains to more than 14 kilowatts on three-phase power, and published the controller firmware and schematic under MIT. The furnace heats metal by inducing eddy currents inside it — a coil carrying high-frequency current never touches the workpiece, and the metal heats from the inside out until it melts. The published design runs on an STM32F103 Blue Pill, uses an LM339 comparator and MIC4421/4422 gate drivers feeding gate drive transformers, and switches FF200R12KS4 IGBT modules. On camera it melts aluminium, brass, copper and stainless steel, pours the steel, and synthesises calcium carbide. Two things will put most people off. First, the 4 kilowatt single-phase build and the upgraded three-phase machine need very different parts, so decide which one you are building before you order anything. Second, the upgraded machine runs at nearly 600 volts DC, and the maker's own cheap power meter, rated for 600 V DC, blew up in a loud explosion during testing. This is not a weekend PCB project. If you want an induction heater for hardening or shrink-fitting, buy a commercial module. If you want to melt metal and are comfortable with high-voltage power electronics, this is a rare, well-documented open design that actually does it.

GOOD TO KNOW

  • —MIT licence with no commercial restriction.
  • —Firmware is present and compiles for STM32F103.
  • —No separate bill of materials — key parts (Blue Pill, LM339, MIC4421/4422, FF200R12KS4, SH1106, DS18B20) are named in the README and the KiCad schematic.
  • —No mechanical CAD for the coil former, crucible holder, or enclosure.
  • —The maker states plainly this documents his own project and is not a build tutorial.
  • —Two very different versions exist: a roughly 4 kilowatt single-phase build and the 14 kilowatt three-phase machine near 600 volts DC — the smaller one is the realistic home build, the larger one is what does the heavy melting on camera.

Parts to buy

12 items

From our check of the build. Exact quantities and part numbers are in the creator’s BOM.

  • STM32F103C8T6 Blue PillFind
  • LM339 comparatorFind
  • MIC4421 and MIC4422 gate driversFind
  • Two gate drive transformersFind
  • FF200R12KS4 IGBT moduleFind
  • SH1106 OLEDFind
  • DS18B20 temperature sensorFind
  • Copper tube for the coilFind
  • Graphite crucibleFind
  • High-voltage capacitorsFind
  • RectifiersFind
  • ContactorFind

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Can I build this?

Printnothing required
BuySTM32F103C8T6 Blue Pill, LM339 comparator, MIC4421 and MIC4422 gate drivers, two gate drive transformers, FF200R12KS4 IGBT module, SH1106 OLED, DS18B20 temperature sensor, copper tube for the coil, graphite crucible, high-voltage capacitors, rectifiers, contactor — there is no full BOM, so work from the schematic
Toolsoscilloscope, high-voltage-rated multimeter, ST-Link programmer, tube bender or mandrel for the coil, and experience with mains-voltage or higher power electronics
Skillsadvanced — this is high-power electronics near or above mains voltage, with risks of explosion if the resonant tank is miscalculated
Timeseveral weekends to source parts, wind the coil, build the driver, tune the resonant frequency, and test at low power before attempting a melt
Cost$$$, dominated by the IGBT module, gate drive transformers, high-voltage capacitors, and graphite crucible
SafetyMains voltage and higher. The three-phase version runs near 600 volts DC. The maker reports a wattmeter exploded during testing. Do not build this as a first power electronics project. Keep one hand behind your back when probing live circuits. Use a variac for initial tests. Molten metal at over 1000°C.

This build involves mains voltage — for adults comfortable with electrical work only.

Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.

Videos

Footage showing brass, steel, aluminium, and copper melts, plus calcium carbide synthesis.

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Gallery

Start here

Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.

  1. 1.Decide which version you are building (The roughly 4 kilowatt single-phase build is the realistic home version. The 14 kilowatt three-phase machine near 600 volts DC is what does the heavy melting on camera. Do not merge the two.)
  2. 2.Read the V3 README and schematic (The maker recommends V3 for any new build for safety reasons. Key part numbers are in the README and schematic; the IGBT module, gate drive transformers and capacitors are not hobby-shop parts.)
  3. 3.Source a graphite crucible(The repository does not specify a crucible supplier or size. You will need one that fits your coil and the metal charge you intend to melt.)
  4. 4.Wind the coil(Copper tube, not wire. The repository does not include mechanical drawings for the coil former.)

Resources

Documentation, files and community threads for this build — we link straight to the original sources and never rehost the creator’s files.

KNOWN ISSUES

  • The single most common mistake is ordering parts for the wrong version. The 4 kilowatt single-phase build and the 14 kilowatt three-phase machine are completely different.
  • This is not a small ZVS induction heater module. Those are sold commercially for heating, not melting. This is a melting furnace with a crucible.
  • The maker states plainly this documents his own project and is not a build tutorial. You will have to fill in gaps.
  • No mechanical CAD is provided for the coil former, crucible holder, or enclosure. You will have to design those yourself or improvise.
  • The maker's cheap power meter exploded during testing because it was rated for only 600 V DC and the machine runs dangerously close to that. Rate every meter, capacitor and cable well above the DC link voltage.
  • The three-phase version runs near 600 volts DC. If you are not already experienced with high-voltage power electronics, build something else first.

Can I build the 14 kilowatt version on single-phase mains?

No. The 14 kilowatt three-phase machine requires three-phase supply. The single-phase version is roughly 4 kilowatts.

Can I use this to harden tool steel or shrink-fit bearings?

This is a melting furnace, not a precision induction heater. For hardening or shrink-fitting, a commercial induction heating module is faster and safer.

Is the firmware ready to use?

The firmware is present in the repository and compiles for STM32F103. You will need to tune parameters for your coil and power level.

Community builds

No community builds yet — be the first, we feature the best ones.

Discussion1

FROM THE COMPAREE TEAM

The maker documented a roughly 4 kilowatt version on Instructables, then upgraded it to more than 14 kilowatts on three-phase power at nearly 600 volts. Which one would you actually build, and what would you melt first?

CompareeTEAM1mo agoedited

Practical notes from our verification: the repository contains the controller firmware (the older V1 and the recommended V3) and a KiCad schematic with PDF, but no separate BOM file and no mechanical CAD for the coil or crucible holder — key parts are named in the README and schematic. The maker states plainly that the video documents his own project and is not a build tutorial; the earlier 4 kW version has its own Instructables guide. The footage is real — aluminium, brass, copper and stainless steel melted, plus calcium carbide synthesis — but the upgraded machine runs from three-phase mains at nearly 600 volts DC, and the maker spells out the electrical, fire and chemical hazards, including acetylene from calcium carbide. This is not a first power electronics project. If you go ahead, use V3: the README says it is the recommended version for any new build, for safety reasons. Correction (4 October 2026): we re-checked this page line by line against the project's own repository, documentation and videos, and fixed errors in earlier versions.

Hector Jimenez Cruz

Hector Jimenez Cruz, publishing as Learning On Demand, built three generations of induction furnace and documented them. The project shows working melts of brass, steel, aluminium, copper, and calcium carbide synthesis.

GitHub

Star the project on GitHub

DISCLAIMER

  • Comparee is not the author of the projects featured here. All rights to each project belong to its creator — every page links to the original source, and we never host creators’ files.
  • Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
  • Building and operating any project is at your own responsibility. Protective equipment, safe workshop practice and compliance with local regulations are the builder’s responsibility.
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