If you think of your wire speed as controlling the overall heat available and the voltage as controlling your arc length and puddle diameter you should be able to dial in.  There is more to it than that, but that is a simple way to think of it for dialing in.

I don't  think the Miller 252 has adjustable inductance, so you will never be optimum for stainless, but it should work OK.

Also, thin stainless is normally done with a tri-mix gas.  Your flux cored wire may operate on EN or EP, and May or may not need gas.

Don't remember if mine is the 252 or 251 but I use Millers.  Mine has a voltmeter and a WFS/amp meter.  Now, most often you are best off to set your volts to the recommended setting then adjust wire feed speed to get it to run within manufacturer's specs and where it works best for the application. 

The amps are relational to the volt and wire feed speed setting (really proportionate to WFS but also directly related to volts.  The more volts you run the more WFS you will need to get a good burn off rate). 

Bottom line, you are not 'converting' volts to amps to know what you are running.  Wrong measurements to convert.

I seldom get at all concerned about amps.  I almost always go by the wire feed speed.  It is a fast and accurate and consistent way to monitor current control. Pull the trigger, let it run for 10 seconds, measure the wire length that came out, multiply by 6 and you have you inches per minute (ipm) to know your wire feed speed (WFS).  So much easier than using a volt/amp meter with no one to help read while welding. 

He Is In Control, Have a Great Day,  Brent

Hey Buddy, I'm not going to change the world on you but I don't see it mentioned so I'm going to mention it. Stick out. Distance the wire extends from the end of the contact tip to work. You need to change it and I think it needs to be a little longer when your welding.

Hear me out. Voltage is puddle fluidity. Amperage is penetration. You don't need to convert anything you need to understand whats happening, thats education.
The term is resistance heating and its what I'm offering as a concideration.
If nothing changes, a longer stickout typically increases penetration slightly, narrowing the bead and thickening the puddle. The wire remains stiffer with less heating.
Shorting the stick out, changing no variables, results in a wider hot bead, less penetration. However...On thin materials, shorter stick out heats the material surface quicker because a wider bead slows down travel speed.

Extending the stick out cools the wire, shortening the arc length and width of the arc column. Base metal stays cooler longer.
Shorten the stick out and the arc length increases because the wire heats quicker, the arc column becomes wider, droplets wetter.

If you think Sub Arc these principles become more apparent. I might also mention, your shielding gas mixture, effects this as well due to arc column profiles and heat input due to shielding gas current potential. I would be curious as to what type of shielding gas mixture is being used.

Getting back on the subject, stick out is a variable. It's also ment to be a consistantly held variable. But if the pot of water doesn't change, and the pasta doesn't change in size, then the variable is where you hold your hand when you place it in the pot?
Thats what I have to offer.

Are you using a weld procedure, or is this an open set-up process?  And, how is the quality verified?  Is visual confirmation of 100% penetration required and possible?

What is the configuration of the weld joint, and what material and thickness are you welding?

I don't want to make trouble, buy my first choice might be GTAW for a thin stainless application.

Aside from that, stick out as a variable is more likely to effect short circuiting mode than spray arc mode with the MIG process, although it could have some effect on both.

My experience has been that hotter processes with wider weld beads require faster travel speeds.  And, in short circuiting mode, longer stick out will result in wire stub outs and loss of shielding gas when the stick out is too long.  Then too, some wires have lubricants that must be burned off, and longer stick out is one way to prevent them from getting into the weld puddle - but you did not say that you are having problems with worm holes.

Brent has a good suggestion.  Maybe the Miller website has some useful information available for download, but if this is an open set-up, then perhaps documenting the voltage and the number setting for the wire feed will suffice once you and/or your team are satisfied with the results.

I read all of the post and found them to be very interesting and informing. One question though, did anyone answer question about how you convert volts to amps? I was really looking forward to the answer to that question. Maybe someone has some magic up their sleeve.

"Keep in mind that not all FCAW electrodes are created equal. The optimum parameters for E71T-1 manufactured by company A and company B are going to be different. So, if one changes to a different manufacturer, the parameters will have to be changed for optimum performance.

Setting the FCAW machine by the seat of your pants is one of the easiest ways of getting into trouble. I've seen it happen time and time again. Use the manufacturer's recommended ranges and start with the parameters they define as optimum."

I agree Al...
And the same goes for stainless steel FCAW electrodes or any other FCAW electrodes for that matter because of the various combinations and amounts of different chemical compositions that make up what is in the core of the electrodes which is the flux... One manufacturer is not going to have an identical chemical composition of another manufacturer of FCAW electrodes... They may be similar but, not identical as I can attest to that from using donated spools of FCAW electrodes from a variety of donors @ the schools I used to teach in.

I also agree that the OP shouldn't have such concern with respect to Amps/current and you brought up what could be the most important variable that is indeed overlooked regardless as to whether or not you just lectured and demonstrated why this parameter is crucial and must be paid attention to a class of students on the very topic only to observe and witness how fast the information I just shared with them went in one ear and out the other! And this was after they already received the very same information regarding this parameter when we started on GMAW prior to covering FCAW... Although, not all of my students had such lousy retention of the curriculum being taught... Just every once in a while I would have a group of well, let's just say - a little slow and dense who ended up becoming welders once I got through with them...

They all would start to whine about the settings on their power sources and wire feeders and yet totally neglected to observe their CTWD... Once  I let them know what they neglected to pay attention to, most of them let out a collective "sigh & Ahahhhh!" along with 2 or 3 who would say: " you see, I told you so!" And talk about the questions about why two spools of FCAW wire would weld differently with identical welding parameters yet, from different manufacturers...  Some of them would suggest that I carry only one brand to avoid any confusion in the shop when practicing FCAW and I would respond; " Well now, do you really think that every business is going to use the very same brand manufacturer of FCAW wire out in the real world?" And their reply would be silent with a deer in the headlights look and maybe an Ahah! every once in a while.
But they learned and most of them did very well for themselves... Excellent description and explanation Al as usual.

Respectfully,
Henry

The "rule of thumb" of 1 amp per 0.001 inch of thickness is based on the assumption one wants to make a CJP groove weld in steel using a square groove preparation. It is nothing more than a starting point from which the user can decrease or increase the amperage to achieve what they are attempting to do.

There are other factors to consider such as the diameter of electrode, position, arc voltage, etc.

Al