On my opinion if you already had a plasma machine might as well as buy the Portable CNC cutting machine (oxy/ace) I had a chance to set-up once, I converted it to a CNC plasma cutting machine instead of oxygen/acetylene,
it can cut any metal I want from aluminum, brass, copper, steel, stainless steel hehehe no if`s not but`s it`s just like a robot arm that instead of you holding the plasma cutter, no confusing torch height control issues.
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This is me cutting Aluminum as you can see the plasma head is just from an ordinary plasma cutter, I just hooked it to the CNC robot and reconfigured one of the solenoids, instead of firing oxygen it fires the plasma trigger.