Long-time lurker, first-time poster. Be gentle. :)
I've spent years hobby-welding with Tig, Stick, Oxy/Acetylene, and plasma cutting and rather thought I was way-cool-bitchin'... then came the MIG machine a few weeks ago. Now I'm back to tripping over my own two feet, making a mess generally... and having loads of fun in the process. Up to a point.
For the record this discussion revolves around a Miller 251 running 0.032 (70S) wire and a 75/25 Argon/CO2 mix at 30ish SCFH on mild steel. Nothing exotic.
My problem is *really* basic, ie, how to convert from a current-based rule of thumb such as "one amp per .001 inch of base metal" into arc **volts**. The MIG machine is CV, not CC (like my TIG, buzzbox, etc), so how the heck do I convert? Funny thing: even the Miller 251 manual itself references output amps (and even mentions the well-worn rule-of-thumb above!), but says absolutely nothing about how to convert a current value into arc **volts**. Looking at the Voltage/Current curves in the manual isn't productive either. These curves specify a possible operating *range* at a given voltage, which, when you work it out to watts gives you an actual min/max heat range in excess of 40%. That's huge.
Can I get some help from the illuminati, please? Maybe a "volts to amps" Rosetta stone for MIG newbies? :)
Roark