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Miller M25 15' gun -- new liner too short

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  • Miller M25 15' gun -- new liner too short

    I have a MM251 and was experiencing some sputtering while welding 14 gauge steel. I've been meaning to change the gun liner for awhile now, so I took the morning to do some maintenance on the machine.
    M25 gun with 15' lead (actually 15' 8" from nozzle adapter to machine-end)

    Renewed and refastened the ground wire to the clamp.
    Took off the nozzle adapter and the threads were boogered (from previous owner), so reshaped the threads with a small file.
    The existing liner had a very small kink, but otherwise looked very new. Tried to undo the kink, but made it worse.
    Installed the new liner after blowing out the hose.
    DANG! Liner was at least 1" short and about 0.25" short of the inside of the conductor. Well, had to do some welding anyway, and put the nozzle adapter and tip adapter on, but of course the wire hung up on the tip adapter. Easy enough to thread the wire through, then install the tip adapter. Whatever.
    So, everything works MUCH better now, but the wire speed is exactly the same (hoped for an improvement in matching to the meter read-out).

    What's a pain is that if (when) I burn a tip, I have to remove the tip adapter because the liner does not extend up into the tip adapter properly (liner too short by 1").
    The question is has anyone had this problem, and have they gently took their "liner stretcher" and stretched the liner to fit?
    The liner was purchased last year, so likely not returnable. (NO, I didn't trim it too short!).
    Thanks
    -doug
    Last edited by DougM; 09-06-2019, 02:42 PM.

  • #2
    Doug, I have never had that problem, as they have always been a skosh too long. It would appear your options are to buy another liner or trim the lead down a bit.

    Was it a genuine miller part?

    I’d probably yank that sap sucker out and stab a new one in.

    Comment


    • #3
      Ryan,
      The new, untrimmed liner was 5/8" shorter than the original. I tried stretching the liner, and with much grunt it did lengthen to what appeared to be about 0.25" longer than the original liner. Stuck it back into the gun lead, and it did peek out of the conductor a bit, but it would easily push back in due to the now-slightly-extended spaces between each coil of the liner. But hey.... the wire (0.035" solid) now feeds like butter!
      The new liner is a Miller product, it's for 0.035 - 0.045 wire, P# 194012, a noticeably thicker profile than the original. I believe I purchased it from some on-line distributor sometime in the past two years.
      I'll have to go scare up another new liner. But until then, it'll work.

      -doug
      Last edited by DougM; 09-06-2019, 06:31 PM.

      Comment


      • #4
        When you indicate trimming the lead, I'm assuming you mean the brass connection on the machine-side of the goose neck? Is that some sort of compression fitting and nut?

        Comment


        • #5
          No, I'm sure he was referring to the spiral wound coil end which is usually 6" longer then required. Was it an opened packed and resealed? Sound like a product that should have been returned, or maybe was and resold to you unknowingly having been shortened when returned. I'd buy another one and save the grief.

          Comment


          • #6
            Ya, I guess it’s a better statement to say the “sheath” for the liner and the wires. It all comes apart. Last one I trimmed by several feet to have a 10’ whip for welding aluminum. Runs 3/64 5356 like a bad dog. I would probably cut it off at the “gun” end. No other reason than that’s always where I’ve always done it.

            Comment


            • #7
              Can we just call it Bowden cable and move ahead to a solution to the instant problem?

              Comment


              • #8
                I have never seen a liner that i didn't have to trim...Bob
                Bob Wright

                Spool Gun conversion. How To Do It. Below.
                http://www.millerwelds.com/resources...php?albumid=48

                Comment


                • #9
                  OK kids, what you have here is a multitude of opportunities, and no problems.
                  1- go blow up some .22 long rifle to make splice sleeves.
                  2- cut the back off an expended round
                  3- find your JB weld or other epoxy that sets up in minutes
                  4- hunt up something to use for a guide wire for assembly - preferably insulated wire that fills the bore of the Bowden tube without forcing
                  5- cut the length of Bowden you need from the old liner
                  6- eyeball the length of tube to insert into the expended .22 round and mark the tube - both pieces
                  7- insert guide wire into tube coming from machine, add minimal epoxy to outside and slide .22 round into place
                  8 -repeat step 7 with short tube and allow epoxy to cure.
                  9- after epoxy is cured remove guide wire - if you used excess epoxy employ a drill the internal diameter of the Bowden to clean out
                  10- chuck a short (6") piece of .045 wire into electric drill and insert wire into Bowden to burnish inside of the splice.
                  11- remove burnishing wire, turn machine on and convert miles of wire to hot glue.

                  Comment


                  • #10
                    Originally posted by Franz© View Post
                    OK kids, what you have here is a multitude of opportunities, and no problems.
                    1- go blow up some .22 long rifle to make splice sleeves.

                    I did #1 today Click image for larger version

Name:	66.JPG
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ID:	601774 used my old home made bullet trap too
                    Bob Wright

                    Spool Gun conversion. How To Do It. Below.
                    http://www.millerwelds.com/resources...php?albumid=48

                    Comment


                    • #11
                      Did you save the brass for future repair parts?

                      Comment


                      • #12
                        Originally posted by Franz© View Post
                        Did you save the brass for future repair parts?
                        I sure did. I have about 400 lbs of brass. I just rebuilt my tumber. Made it Hi Performance
                        Bob Wright

                        Spool Gun conversion. How To Do It. Below.
                        http://www.millerwelds.com/resources...php?albumid=48

                        Comment


                        • #13
                          And I happen to know you have ample sawdust to tumble with.

                          Add a bit of Vinegar to the batch and it should shine up nice.

                          Let the copshop here tumble a heap of brass from the range once and watched em snivel. It was all clean on the inside like they dreamed of, but it was scratched on the outside. I didn't tell em to run it again with sawdust or corncob.

                          Comment


                          • #14
                            Noel,
                            The package was heat-sealed as normal, with the cardboard packaging part stapled onto the top of the bag, with no apparent indications that it had been tampered with or modified. The liner was coiled nicely, held in coil with four black zip ties that looked exactly like the ties I took off other new liners.
                            I was thinking the same thing (had been erroneously trimmed, returned, resold) upon installing it into the lead, but didn't raise any bells when opening the package. The normally-trimmed end appeared to be cut cleanly with no burrs and looked just like the nut-end.

                            The old liner is 15' 6" long. The new liner *was* 15' 5-3/8" before stretching. Now it's a 'variable length' liner.
                            I had to weld some 22 ga stuff to 10 ga, so I switched to 0.025" L-56, and that fed perfectly. Surprising.

                            Anyway, the machine had been steadily getting worse before I did a few typical maintenance changes to it the other day. Changing out the older liner for the new stretched liner may or may not have been the whole factor that corrected the sputtering problem.

                            Comment


                            • #15
                              My MM251 stuttered and popped on starts. Talked to Miller, Miller said to remove either the # 8 wire or the #79 wire depending on the machine serial number from the contactor to get rid of the hot start feature. I removed the #8 wire on my machine, a 2003 model, and the machine has never run so sweet. No more popping and stuttering on startups.


                              The yellow wire is the # 8 wire on my machines contactor.

                              https://www.amazon.com/WeldingCity-1...59XT06107JG1YA
                              Last edited by tackit; 09-09-2019, 08:06 AM.

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