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  1. #1
    Join Date
    Nov 2013
    Posts
    17

    Default Next model TIG inverter pulsing suggestion for Miller

    I'm only a noob, but I play with my Dynasty 200 DX's pulsing a lot. One thing that I reckon would be super useful is to display the average amps that a particular pulse configuration gives. I can calculate it myself, but it's too much for me to do in my head on the fly so I just wing it and often get it wrong. E.g. today I was doing some stuff with reasonably thick mild steel, maybe 0.120" or 0.140", and started at 40% peak, 40% background and 150A main amps. That wasn't enough so I kicked it up to 160A and then further to 170A but still not enough. In hindsight after running it through my calculator it was still too low.

    On the computer I have a programming environment called Python so it's a 2-liner to put in my algorithm:

    Code:
    >>> def pulse(peak, background, main):
        return peak / 100 * main + (1 - peak / 100) * background / 100 * main
    >>> pulse(40, 40, 150)
    96.0
    >>> pulse(40, 40, 160)
    102.4
    >>> pulse(40, 40, 170)
    108.8

    but as you can see I was too low and should have bumped up some of the parameters. Rather than having to come inside and fire up the computer, it would be great to have some way of displaying the average amperage output on the machine once you set in the pulse parameters. Unless it's already there and I just don't know about it?

    E.g. today it would have saved me making a mistake when I thought I was in the right ballpark initially. I then had to fix it. No big deal but I ended up putting in too much heat by running over my mistake a second time to ensure penetration.

    I tend to use two modes, 1 PPS for butts and 150 PPS for fillets, same pulse parameters just changing the frequency.

  2. #2
    Join Date
    Dec 2007
    Location
    Oklahoma
    Posts
    696

    Default

    Quote Originally Posted by Legion View Post
    I'm only a noob, but I play with my Dynasty 200 DX's pulsing a lot. One thing that I reckon would be super useful is to display the average amps that a particular pulse configuration gives. I can calculate it myself, but it's too much for me to do in my head on the fly so I just wing it and often get it wrong. E.g. today I was doing some stuff with reasonably thick mild steel, maybe 0.120" or 0.140", and started at 40% peak, 40% background and 150A main amps. That wasn't enough so I kicked it up to 160A and then further to 170A but still not enough. In hindsight after running it through my calculator it was still too low.

    On the computer I have a programming environment called Python so it's a 2-liner to put in my algorithm:

    Code:
    >>> def pulse(peak, background, main):
        return peak / 100 * main + (1 - peak / 100) * background / 100 * main
    >>> pulse(40, 40, 150)
    96.0
    >>> pulse(40, 40, 160)
    102.4
    >>> pulse(40, 40, 170)
    108.8

    but as you can see I was too low and should have bumped up some of the parameters. Rather than having to come inside and fire up the computer, it would be great to have some way of displaying the average amperage output on the machine once you set in the pulse parameters. Unless it's already there and I just don't know about it?

    E.g. today it would have saved me making a mistake when I thought I was in the right ballpark initially. I then had to fix it. No big deal but I ended up putting in too much heat by running over my mistake a second time to ensure penetration.

    I tend to use two modes, 1 PPS for butts and 150 PPS for fillets, same pulse parameters just changing the frequency.

    To each his own but you are sure making this complicated.

    Oh and .120" or .140" anything need not be in the same sentence as "thick".

    Griff

  3. #3
    Join Date
    Dec 2008
    Location
    west central Florida
    Posts
    86

    Default Checking the amps

    After setting the pulse controls, if I want to know the amps I rest the cup on my bench with the tungsten close to the table, use my left hand (my right hand is holding the torch) to block the arc, step on the pedal and look at the amp reading on the machine...adjust if necessary

  4. #4
    Join Date
    Nov 2013
    Posts
    17

    Default

    Quote Originally Posted by griff01 View Post
    To each his own but you are sure making this complicated.
    It took me about 30 seconds to put in the algorithm.

    I can keep a diary of what settings work but as a hobbiest I don't have production lines so each job is going to be fairly unique. Working out the effects of pulse parameters would simplify my life because then I could say something like "what if I change peak time from 40% to 60%, how much will that increase my average amps" without doing little test runs first or going inside to check on the computer. Here are some examples:

    Code:
    >>> pulse(40, 40, 150)
    96.0
    >>> pulse(60, 40, 150)
    114.0
    >>> pulse(40, 40, 100)
    64.0
    >>> pulse(60, 40, 100)
    76.0
    >>> pulse(40, 60, 150)
    114.0
    >>> pulse(60, 60, 150)
    126.0
    >>> pulse(40, 60, 100)
    76.0
    >>> pulse(60, 60, 100)
    84.0
    So I can quickly see the different effects of different parameters on my average heat input. I can always do test runs but this would give me an idea in advance "oh, ok, I'm putting in an extra 15A, be prepared to move a bit faster".

    Quote Originally Posted by griff01 View Post
    Oh and .120" or .140" anything need not be in the same sentence as "thick".
    Yeah, that's a good point. Thick compared to the .060" I mostly find myself welding, I guess.

  5. #5

    Default

    Quote Originally Posted by griff01 View Post
    To each his own but you are sure making this complicated.

    Oh and .120" or .140" anything need not be in the same sentence as "thick".

    Griff

    People like Legion are the reason we no longer live in caves.

    Question EVERYTHING!
    =======================
    Miller 211 AutoSet
    Miller Dynasty 200 DX
    Thermal Dynamics Cutmaster 42

    "The Sleep of Reason Produces Monsters"
    Francisco Goya

  6. #6
    Join Date
    Sep 2012
    Location
    AZ
    Posts
    46

    Default Incorrect

    Quote Originally Posted by Legion View Post
    ... started at 40% peak, 40% background and 150A main amps. That wasn't enough so I kicked it up to 160A and then further to 170A but still not enough. In hindsight after running it through my calculator it was still too low.

    On the computer I have a programming environment called Python so it's a 2-liner to put in my algorithm:

    Code:
    >>> def pulse(peak, background, main):
        return peak / 100 * main + (1 - peak / 100) * background / 100 * main
    >>> pulse(40, 40, 150)
    96.0
    >>> pulse(40, 40, 160)
    102.4
    >>> pulse(40, 40, 170)
    108.8
    Quote Originally Posted by Legion View Post
    ... started at 40% peak, 40% background and 150A main amps.
    You probably meant "started at 40% peak, 40A background and 150A main or peak."

    If you spend 40% of the time on Peak Amps, then you spend 60% of the time on Background Amps. The weighted average is then:

    Avg = .4*PeakAmps + .6*BkgrndAmps
    Your first example then becomes:
    Avg = .4*150 A + .6*40 A = 84 A

    Your code should look like this:

    >>> def pulse(peak, background, main):
    return peak / 100 * main + (1 - peak / 100) * background

    It's good to do a simple sanity check on code. In this case, calculating a simple, unweighted, average in your head would've indicated an error.

    (40+150)/2 = 95.

  7. #7
    Join Date
    Nov 2013
    Posts
    17

    Default

    According to my Dynasty 200DX user manual background amps is set as a percentage of main amps, not as a raw amps value.

  8. #8
    Join Date
    Dec 2010
    Location
    Sutton, MA
    Posts
    31

    Default

    I think average amps only tells a very small part of the story when using pulse. You can have two different sets of settings with the same average amps but wildly different arc and puddle behavior.

  9. #9
    Join Date
    Nov 2013
    Posts
    17

    Default

    Oh, definitely. Particularly at 1PPS, which I find I use for filling gaps, usually where square tube butts onto a radius corner of another tube. In that situation I'm more interested in the individual parameters. But at higher frequencies I think the average would be useful. I like the high frequencies for focusing in fillets.

    It's probably unnecessary. I'm just a noob tinkering. I should just concentrate on basics and get my skills rock solid. I've seen your welds, zank, and read some of your early threads on weldingweb. If I could weld half that well I'd be happy and from memory you don't use pulse at all.

  10. #10
    Join Date
    Jun 2014
    Posts
    23

    Default

    Speaking of pulse, I found a great article by some Miller Welding Engineers on the Fabricator.com website.

    http://www.thefabricator.com/article...tainless-steel


    With the exception of the whole "reducing heat by 60%" bit, it is a very informative article with pictures and most importantly--numbers & data.
    HTP Invertig221 D.V. Water-cooled
    Eastwood MIG175 w/spoolgun
    Eastwood Versacut40 Plasma cutter

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