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anyone run pre/post flow on MM252 for steel?

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  • anyone run pre/post flow on MM252 for steel?

    Any good reason to run pre/post flow with 0.035 wire and 75/25 gas for mild steel? Or am I just wasting gas?

    Currently have 0.5 pre flow and 2 sec post flow

    Thanks

  • #2
    anyone run pre/post flow on MM252 for steel?

    Anyone?

    Comment


    • #3
      Originally posted by ericher69 View Post
      Anyone?
      i use it on mine at work. figure it keeps the filler from oxygen contamination while it's still glowing when you let off the trigger. i use 0.2 for preflow and i think you want 10 seconds of postflow per every 100 amps. this might be completely wrong, but it's what i do.

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      • #4
        anyone run pre/post flow on MM252 for steel?

        I use both for Tig but only post on Mig.
        I don't like any delay on my pre/ when I hit trigger I want arc. I use a little post 2-sec. that keeps gas over puddle if I pause for a sec or two to let puddle cool if wide gap & filling or stitching etc. but I don't like any delay in my pre. And in every day welding when let off trigger I'm normally moving on anyway & just blow gas into the air.

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        • #5
          Originally posted by gnforge View Post
          I use both for Tig but only post on Mig.
          I don't like any delay on my pre/ when I hit trigger I want arc. I use a little post 2-sec. that keeps gas over puddle if I pause for a sec or two to let puddle cool if wide gap & filling or stitching etc. but I don't like any delay in my pre. And in every day welding when let off trigger I'm normally moving on anyway & just blow gas into the air.
          I must say even with my 0.5sec preflow it did take a little while to get used to.

          I still forget to pause when in a hurry with the post at times.

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          • #6
            ive usea a mm200 for over 25 years, no pre/post option on the 200, recently i purchased a 252, by all means, it is not a waste of gas, most people waste more gas by using too high of a pressure, i run about 12 lbs with no issues, always have been around 12, i will up it to 15 if i see the need, while on the topic of gas, ditch the 25/75 when empty, get 84/16, 85/15, what ever is available, then you can spray weld with the 252

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            • #7
              Originally posted by kevin View Post
              ive usea a mm200 for over 25 years, no pre/post option on the 200, recently i purchased a 252, by all means, it is not a waste of gas, most people waste more gas by using too high of a pressure, i run about 12 lbs with no issues, always have been around 12, i will up it to 15 if i see the need, while on the topic of gas, ditch the 25/75 when empty, get 84/16, 85/15, what ever is available, then you can spray weld with the 252
              I was considering something else than 25/75 but have heard unfavorable things about the bead in short circuit with gases containing oxygen.

              Also that I would be wasting money using a gas for spray when I mainly do short circuit.

              Please elaborate or give me your thoughts on this

              Thanks

              Comment


              • #8
                I use .5 sec. pre and 3 sec. post - it took a while to get used to the pre, but I like being able to tap the trigger and check what the flow rate is set for, WITHOUT having to grab the cutters and trim off wire every time. The post flow pretty much takes the color out of the weld before it's done, just seems like a good idea. (I guess the word police don't like my usual term for cutters, had to replace a bunch of ****'s :=)

                Spray - done it once, it was fun but from what I've read it's not good for out of position or thin stuff, BOTH of which I do a LOT. My LWS guy suggested dual shield wire instead, don't need a second bottle and it's good for all position like regular hard wire... Steve

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                • #9
                  dual shield is very expensive compared to hard wire. the gas used to spray is almost the same as 75/25, it 85/15, no oxygen in the mix, and it is about the same price, the only difference is the ratio of argon to co2.since you have a 252, which has more balls than most people need, why not feed it the gas that can spray or less exciting go in globular transfer, these processes are stretched with the common 75/25. the suppliers will tell you all kinds of things about other mix,s, other than 75/25, because, most dont, or wont stock the sprayable gas,s. lets say you get the 85/25, and you dont weld real hot, you wont be able to tell the difference between the 2 gas,s. all i am trying to say is, since you have a hot rod, feed her the hi test

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                  • #10
                    anyone run pre/post flow on MM252 for steel?

                    Kevin,

                    You recommend 85/15 for spray?

                    I will call around today to see if I can get some in the smaller cylinders.

                    Comment


                    • #11
                      I use .2 for pre. Like previously mentioned, It's nice to pull the trigger to check the flow without having to cut wire. I use 15cfh in the shop.
                      Lincoln Vantage 400
                      Trailblazer® 302 Air Pak™

                      Miller Dynasty® 350
                      Millermatic 350P Aluminum
                      Millermatic® 252
                      Syncrowave 351
                      Lincoln LN-25 Pro

                      Multimatic™ 200

                      XR-Aluma Pro Gun
                      Diversion™ 180

                      Spectrum® 625 X-TREME™

                      Thermal Dynamics® Cutmaster® 52
                      Victor Oxy/Acetylene Set

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                      • #12
                        Kevin, as pretty as it is, the 1G limitation (I'm told) for Spray keeps me from getting too excited about going there - haven't priced the dual shield stuff yet so that may be a deal breaker.

                        I have a Case backhoe and 2 45 horse tractors, and have gotten addicted to MIG and plasma after 35 years of using only gas and stick, so am hoping to extend the MIG to OOP and heavier stuff.

                        Supposedly Spray isn't workable OOP much, and I don't have a 7 ton positioner, nor do I wanna flip my 580 upside down

                        Ain't gonna pull the trigger on either one til I know more... Steve

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                        • #13
                          i hear ya steve, i dont do any spray welding, if its that thick, i bring out the 7018, i prefer stick welding on structual welds on heavy equip. have you used the chart for setting up the machine to weld, the first time i used my 252, was on half inch material, i set it at the setting that is on the chart, it went into spray right away, i fiddeled with the settings and really got it to fry, speaking of frying, the gun just about burnt itself up. i just went thru this delima with miller, they swapped out the stock gun with a heavier gun,made for higher amps as for dualshield, why, i asked myself the same question a while back, unless you are running big beads all day long, then it would be a good thing. if i am correct, the wire is about five bucks a pound. i just bought my 252 right around xmas time, and work is slow in the shop, mayby, this coming spring and summer, if i get any heavy jobs, like a cutting edge on a bucket, then i will give the mig a shot

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                          • #14
                            Sounds similar to my experiences - I have Miller's "slide rule" mig and stick calculators, and just checked the online version - their only recommendation for 1/2" steel is spray, 98/2 @ 29-30 volts - that's definitely spray country.

                            I've done a bit of 1/2 and 3/4 fabbing with the 252/.035 wire, I just do multiple stringers til it's at least as thick as the material - that experience is mostly what's causing me to look at aftermarket mig guns vs. melted torches.

                            As expensive and time consuming as it is to change liner, tip, gas, wire, etc, plus the higher cost of going to Outershield wire, I'll probably do the same as you - drag out/dust off the stick machine and 7018 (after tacking with wire) for the heavier (especially OOP) stuff... Steve

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                            • #15
                              i run a small 1 man welding shop, i do fab and repair, when i get any type of construction equipment and the material is 1/4" and up i have always used the stick, but i am rethinking that stratedgy, i may go to the mig more since i have the 252, it runs great when used hot, most migs work better in the low end than the top, but this 252 is made for high amps. i like stick welding, but it is time consuming. my mm200 still runs good, then again, it runs better in the low range, granted, i have used it since 1986 flawlessly. i would hate to over work her in her senior years, she has been very good to me.

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