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MM 210 Liner Replacement Question

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  • Archaic

    Someone more knowledgeable will hopefully come along, but I will take a swing at your question. Understand that my experience is with a MM251 and a Miller M25 gun.

    No, DO NOT cut the steel liner back to the gun assembly brass fitting. I have gone to Bernard guns on my 251. If you looked at one of them you would see that on the machine end, rather than a section of steel liner sticking out, there is a brass nipple that when the gun is seated into the machine and clamped down the end of the brass nipple is approximately 1/16" (or less) from the roller. From the center of the roller the wire is in tension to the spool side. From that point to the gun side it is being pushed. Cutting off the liner as you questioned in that area would just give space for the wire to buckle and birdnest. The liner should not touch the roller, but be as close as possible.

    Liners, as they come from Miller, and after you cut it, tend to have a very sharp, rough edge towards the wire. I file this down to produce a very smooth edge. No chance for the wire to snag entering or exiting the liner.

    I am not sure how the Century liner position effects amperage. This should not be true on the Miller. The liner does not carry current. Current to the wire occurs at the tip.

    The Miller O&M can be somewhat confusing. The liner should be cut 3/4" OUTSIDE the head tube. Not 3/4" back INSIDE the head tube. The gun end of your liner should fit up into the brass adapter providing a smooth transition from liner into adapter into tip. I will attempt to attach a picture from the M25 O&M to this message showing this. You can download the M25 O&M from the Miller site.

    Whether the tip sticks out, is flush, or is recessed is a function of which nozzle you have. For most welding, I would suggest that you use the 200258, 1/2" orifice, flush, or what I typically used was the 169726 5/8" orifice, flush. This is not completely true, but recessed tip nozzles tend to be used for spray arc welding, tip stick out nozzles for hard to get to areas in welding. Generally speaking, you will get better gas flow and welding when using a flush nozzle. But, you may find that for your style of welding a recessed or stick out nozzle works better.

    Hope that I helped and did not give bad information.


    Well, I can't upload the file as it exceeds the fourm's 100 KB restriction. Rats! What you should have is 3/4" of liner sticking out past the end of the head tube when cut. Make sense?
    Attached Files

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  • davvet2
    started a topic MM 210 Liner Replacement Question

    MM 210 Liner Replacement Question

    I replaced the liner in my 210 last year trying to solve burn back problems. Instructions said to cut 3/4" off the liner at the gun head, which I did.

    Now, I realize that there is liner sticking out of the brass on the roller end and the assembly isn't seated all the way down. (see photo)

    It's about 1/2" away from the rollers, but the steel liner protrudes and it's 1/16" away from the rollers.

    Do I need to cut the steel liner back to the gun assembly brass fitting and readjust? If I do this, will it make my liner too short?

    After I called Century and they told me the gun assembly on my 140 needed to almost touch the rollers because it affected amperage, I wondered if the same thing might be true on the 210.

    Also, should the contact tip stick out past the shield cup or is it recessed?

    Finally, does Miller have tech support by phone?