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
============================
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.
Results 1 to 10 of 12

12282012, 03:43 PM #1Member
 Join Date
 Jul 2012
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 87
Miller 211 MVP IPM y=(40/9)x+(60(400/9))
==============
Miller 211 MVP
Hobart StickMate LX 235
Lincoln AC 225
CutMaster 42

12282012, 05:39 PM #2
Or you could simply use a Lincoln wire in/min measurer like I use, though really, what would the point be. The specs say the unit runs from 60 440 in/min wire loaded. Devided out and there ya go, no math needed.

12292012, 07:16 AM #3Member
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 Jul 2012
 Posts
 87
And here all these years I thought division was math.
Can you show me how your simple division method works to calculate IPM on the 211 MVP?
If yours works I'd like ask these guys why they didn't see such a simple method.==============
Miller 211 MVP
Hobart StickMate LX 235
Lincoln AC 225
CutMaster 42

12292012, 07:49 AM #4
Sorry, no extensive math required. and yours is flawed anyways as you didn't take into account wire resistance in the liner, nor wire drive tension. You took into account no wire present at all, just a free wheeling hub. which as the Miller graphs show is quite different loaded and spinning free.

12292012, 09:43 AM #5
Miller 211 MVP IPM y=(40/9)x+(60(400/9))
Way too many variables to put an exact formula to the fractional wire speed selector, could be why Miller didn't put the wire speed on the selector.

12302012, 08:23 AM #6Member
 Join Date
 Jul 2012
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 87
1. Since you didn't post it I must assume your nonmath division method doesn't exist?
2. It's not necessary for me to take into account those variables as I'm sure Miller engineering did so prior to posting the spec values with the machine documents. Do you really think Miller would post a specification that did not take those variables into account. I suspect if this were the case the specs would read:
IPM Range: 60  460 (But you may have different results.)
Yeah, right.==============
Miller 211 MVP
Hobart StickMate LX 235
Lincoln AC 225
CutMaster 42

12302012, 08:30 AM #7Member
 Join Date
 Jul 2012
 Posts
 87
They don't seem to have a problem calculating those values on their other machines, especially given they can design a digital machine that can be set to increments with a value of 1 IPM. I'd bet their high end computerized systems can be set to fractions of an IPM.
I guess I assign too much intelligence to someone who can design a machine as complicated as this. There have been a few high school dropouts that could do so over the years but they're significantly few and far between.==============
Miller 211 MVP
Hobart StickMate LX 235
Lincoln AC 225
CutMaster 42

12302012, 08:34 AM #8Member
 Join Date
 Jul 2012
 Posts
 87
OIC what I'm missing.
Y'all think y=(4.5*x)+15.5 is complicated math.
Doh!==============
Miller 211 MVP
Hobart StickMate LX 235
Lincoln AC 225
CutMaster 42

12302012, 08:56 AM #9Member
 Join Date
 Jul 2008
 Posts
 36
Your math formula assumes a linear potentiometer on the wire speed control, if it is an audio taper your formula would not be valid. Wouldn't it be much simpler to set the dial at a given number on the dialpull the trigger for 6 seconds, measure the length and multiply by 10? Also any fluctuations in line voltage will throw off your theoretical speednot by much but it will make it less accurate as voltage impacts speed on the drive motor.

12302012, 09:30 AM #10
Any welder on here that mig welds for real, will tell you the only TRUE way to determine wire speed is to pull the trigger for 60 seconds and measure. A welder with digital display will never give you 100% accurate readings unless there is a sensor after the drive wheels measuring the actual tensioned speed. And anyone who doesn't take into account ALL variables before trashing someone else is just a flamer themselves.
I personally have the invision 352 MPA plus, I still hold the trigger for 6 seconds and measure x 10 for pretty accurate readings. Now I have an idea of how far off the digital reading is for this spool of wire.
And if you are even smarter as a mig welder, you would know that most people who have welded on older machines would find there correct settings by pulling trigger for 10 seconds and multiply by 6. Then test and see if it worked. If they liked the setting, they would mark it and give it a number so they know what it was.
Other things only welders take into account and not you:
Length of gun/liner
Installation of liner
Tension on wire spool
Tension on wire
Gun curve
Straightness of cable during welding
After all this, you should realize that all you were able to figure out is the "mathematics" of what the Drive Roll free spool speed will be. Learn to weld, then you will realize that mathematics isn't always the best.
Answer:
Miller can't take into account post consumer products, or tension. How can they?