NOTICE: Only Miller can weigh in here and say if this is accurate or not since their math gurus designed the machine.

I talked to some math gurus where I work and here's what they came up with for calculating the relationship between knob marks and the actual wire feed speed for the Miller 211 MVP machine. I'm not a math guru so I can't proof their work but playing with various values of X the results for Y sure look like the fit the bill.

This formula is based on the relationship between the dial indicator marks of 10 to 100 and the real specs of the machine as posted by Miller of 60 to 460 IPM.

Using Y as the unknown and X as a value between 10 & 100:

The forumla is: y=(40/9)x+(60-(400/9))

That also works out to: y=(4.444444444*x)+15.55555556

Simpler (but less accurate) to round off to: y=(4.5*x)+15.5

Couple of rounded examples are if the dial is set to:

25 then IPM is 127

70 then IPM is 326

99 then IPM is 455

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If you want to plot a graph in Excel:

Put the known data points into two rows (Row A 10 & 100, Row B 60 & 460)

Select the 2x2 grid you just created

Then choose Insert -> Select: Scatter (With Straight Lines)

This will draw a line you can trace intersecting lines on from the two axes and find the actual IPM.