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  • Contact Tip Service Life

    I was welding several 3/4" square stock rods together (end-to-end) using 0.030" E71T-11 flux core wire. using a Handler 190 and trying to maintain a short stick-out distance. Weld wire and/or base metal melts onto the surface of the contact tip. What is the appropriate method of cleaning the contact tip? Should its rounded end be sanded clean with emery cloth or a hand file? What dictates need for replacement?


  • #2
    Keep a pair of ****s or side-cutters handy for when the wire blob actually sticks to the tip. After getting the melted blob off, you can remove the tip and file it a bit to make the hole clean enough to be useful again. Sometimes, you'll have to unscrew it while the wire is still stuck to it (which springs around the wire throughout the gun, but it's long enough) and then after it's unscrewed you can feed enough wire to cut behind it. This is usually one you'll toss and replace.

    Wow, pretty zealous censor here. "D!kes" is a perfectly acceptable and common portmanteau of "diagonal cutters," and is a different spelling than the synonym for certain ladies.
    Last edited by MAC702; 02-23-2019, 08:53 PM.

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    • #3
      Originally posted by Badbmwbrad View Post
      I was welding several 3/4" square stock rods together (end-to-end) using 0.030" E71T-11 flux core wire. using a Handler 190 and trying to maintain a short stick-out distance. Weld wire and/or base metal melts onto the surface of the contact tip. What is the appropriate method of cleaning the contact tip? Should its rounded end be sanded clean with emery cloth or a hand file? What dictates need for replacement?

      The wire is wound on a spool. The size and wire type results in a cast and helix. That causes the wires to spiral as it's being pushed. That rotation causes tip erosion. That turns the end of the orifice into a elongated oval or elliptical shape. That causes a change to wire contact surface and conduction of electrical current.

      To add to what Mac702 mentioned, some will dress the orifice in the tip with a tip cleaner. Most wire feed welding issues are due to poor work clamp connections or worn contact tip and poor current transfer. The tip should be clean and shiny, free of metallic deposit to avoid current loss due to cross firing to the nozzle.

      And if the wire is burning back and melting into the tip...you have other problems that need addressing. I'd start with short stick out and WFS.

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      • #4
        Thanks for the information. My understanding is it's OK to file down some of the tip to remove stuck-on filler metal. I was welding with the voltage tap set on 6 of 7 at 40% wire feed speed. My stick-out was as short as possible and the wire probably burned back toward the contact tip.

        PS I use genuine made-in-Japan Welper pliers which are quite handy for clearing flux from the gas hood, removing the tip, etc.

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        • #5
          Going forward buy your tips by the handfull or bulk packet. That makes them about 50¢ apiece. Whether it is bad technique or just an awshucks moment it's quicker and easier to just slap in a new one than do a recovery while working. If you feel like one can be restored and reused play with that later. I generally don't mess with them much.

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          • #6
            Had my HH 140 about 6 years now, think I have replaced tips about 4 times other wise in quiet moment in shop I sit and clean MIG gun, nozzle and contact tip and such and other tools... Preventative maintenance you know.... ALWAYS want tools ready to go when I need them..... I used to work with a bunch of dummies that would put broken power tools back in locker without at least labeling them as "defective" hated getting out on job site with broken tools....

            Dale
            Last edited by Dale M.; 02-24-2019, 09:16 PM.
            Lives his life vicariously through his own self.

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            • #7
              Badbmwbrad, If the welding wire is just lightly "welded" to the front of the tip, it is easy to save. Stretch out the gun cable so it is in a straight line. Unscrew the tip using a pair of pliers. Grip the tip only tightly enough to unscrew it. Use the special pliers. You don't want to deform the tip. In fact, after you loosen it, you can probably unscrew it the rest of the way with your fingers. When the tip is unscrewed, feed some filler wire so you have an extra couple of inches of wire sticking out the back of the tip. Cut the wire off near the gun. Hold the tip gently but firmly, maybe using small vise grips, and grind the tip clean and flat with the fine wheel on your bench grinder. Pull the wire out through the back of the tip. File the hole round with an oxy-acetylene tip cleaner. Don't ream it out too much, just get it round. Pretty up the outside circumference of your tip with a file. Feed the filler wire through the back of the tip and screw the tip back onto the gun. Resolve not to do THAT again and get back to welding. I usually throw my mucked-up tips into my welding drawer and fix a handful at once (after I have messed up my last new one and I want to continue welding rather than making a trip to the store). Note to self: Keep an eye on the consumables stock situation. Developing your welding skill and paying attention to stick-out will not provide you with many opportunities to develop your tip-rescuing skills. ~0le
              "If a problem can't be solved, enlarge it." (The 34th president of the United States)

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              • #8
                I found a WYPO tip cleaner in the accessory bag attached to the Trek 180. It will be useful in cleaning dirty contact tips.Click image for larger version  Name:	418wifPySBL._SX425_.jpg Views:	0 Size:	21.6 KB ID:	703957
                Last edited by Badbmwbrad; 03-02-2019, 09:02 PM.

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