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Plasma cutter, small (Miller Spectrum 375) ID:52

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Type Plasma Cutter
Make/Model Miller Spectrum 375
Serial number ??
Original owner William
Loan status Donated to Protospace
Arrival date July 2012
Location Welding/Metalworking Shop
Functional status Working
Usage permissions Open to Members & Friends
Certification Demo/Notes Required Post to list to request demo
Wiki ID 52

Usage Notes

  • Cuts metal via plasma arc
  • Eye protection must be worn at all times, (welding helmet or oxy/ace goggles suffice)
  • Leather gloves/sleeves required
  • Place workpiece on a raised surface, do not cut flush against floor or workbench
  • Attach grounding clamp, ensure good contact (no paint)
  • Set cutting power & air pressure according to workpiece thickness
  • NEVER cut without air supply at sufficient pressure, requires airflow for cooling
  • Flip up yellow trigger safety
  • Trigger is dual-mode. Tapping trigger toggles air supply on/off. Holding trigger starts plasma arc/cut
  • After cutting, let air flow for several seconds to cool tip before tapping off. Air flow will shut off automatically
  • Arc begins as low-power pre-arc before full-power arc when good contact through workpiece is established.
  • After 5 seconds if good contact is not established, pre-arc shuts off as a safety feature. Pause and start pre-arc again.
  • DO NOT make contact with tip to workplace, this melts the tip.
  • Tips and electrodes gradually wear out, are consumable.

  • Is currently wired for 240V. Can run on 120V as well, with reduced cutting capacity. Swapping plugs is not sufficient, internal wiring must be changed to become 120V. If wiring is changed, tape a note to the machine informing others such. When running on 120V, after rewiring inside, use the adapter cable made for this.

  • If 120V breaker trips, breaker is 20A breaker on left electrical panel, very bottom left (might change, but look there first if it tripped). Tripped breaker switches are between on and off. Breakers must be turned all the way off before back on. Lower cutting power, lower duty cycle to avoid tripping breaker again.

  • If 240V breaker trips, too much power is being used.


  • 240V or 120V, 20A
  • At 120V, Cuts max of 3/16" steel continuously. Will cut 1/2" very slowly, 25% duty cycle or the breaker will repeatedly blow.
  • At 240V, Cuts max of 1/2" steel continuously. Will cut 5/8" very slowly. Use duty cycle stated on cutter itself.