How to Build a Welder Choke

The choke mechanism controls the current to the arc welder.
The choke mechanism controls the current to the arc welder. (Image: Thinkstock/Comstock/Getty Images)

The "choke" mechanism controls the amount of current, or amperage, that flows through an arc welder. Arc welders use direct current, rather than alternating current. If the welder is well constructed, the power flowing through the arc welder will be "clean," that is, relatively steady and constant. The primary means of controlling the arc welder's power, then, is via the choke mechanism.

Things You'll Need

  • Steel rod
  • Copper wire
  • Soldering iron
  • Soldering compound
  • Arc welder

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Disassemble your existing welder. If you are rebuilding a welder, you will be able to see the choke mechanism. The choke mechanism is simply a metal rod that moves through a hole in a wire coil. The current moves through the wires toward the arc points. If you are building an arc welder from scratch, imagine you are creating a metal finger and pointing it through the hole in a copper wire doughnut, in a design similar to that of an electric magnet or guitar pickup.

Coil stripped, insulated copper wire neatly in a tight doughnut shape, leaving a hole in the center just big enough for the metal core.

Place a heat-resistant nonconductive barrier to shield the transducer rod from physical contact with the coil.

Place a ferromagnetic iron rod through the center of the coil. It is the movement of this rod through the coil that varies the amperage that the choke lets through.

Attach the positive and negative leads to either end of the wire coil and on to the arc welder.

Solder or otherwise attach an insulated knob to the ferromagnetic iron core. This knob moves the core back and forth within the coil, adjusting the amperage.


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