Lincoln 180C MIG Welder

Discussion in 'Metal Boat Building' started by cahudson42, Dec 11, 2007.

  1. kmorin
    Joined: Apr 2005
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    Location: Alaska

    kmorin Senior Member

    MIG systems choice

    cahudson42,
    The bead shown in your photos was done with a large filler rod contibution compared to the heat that is why the weld is overly rounded. What this does is to keep the puddle molten but not so 'wet' or fluid that it drops through leaving a hole. The method is done with TIG to keep the molten area covered with Argon and clean, but at the same time the back side of the molten puddle melts the inner side wall of the parent metal to give a single pass weld with good control, great penetration and no finish after the weld is done.

    The only way to get the bead shown is with filler. If you had each side plate of parent metal slightly flanged or had a sacrificial edge that was clamped flat together, fusion can work in aluminum but its not considered reliable without having edges of 2 or 3 T available to fuse. To form a hull panel then flange it for this type of weld joint would cost much more than filler.

    The aluminum weld puddle in TIG is 'wetted' by the argon's cleaning action, the AC polarity cycle changes lifting the Al-Oxide, as well as the heat of fusion the parent metal. The filler rod alloy is mixed to create a weld zone of better strength and ductility than purely fused parent metal. So adding filler creates a weld of a third alloy- parent metal on both sides mixed with the filler yields the 'third' or mix alloy that cools (freeze) into a more ductile, less brittle alloy.

    In the case of your production press formed boat, the welds were probably done with 4043 an incredibly nice flowing rod of very low final strength compared to 50_ _ series filler. The result is the overly rounded but still controlled puddle shown.

    Some of the terms in current MIG power supply discussions need some definition as a square wave could be said to 'pulse' on the rising portion of the wave form. Also the benefits of DC wave forms to different metals in different thicknesses and positions of weld are not fully understood by the overall MIG welding community yet.

    This is little like the acceptance of PC's and their continually changing impact on the way we interact. Here we are 'talking' about welding on a virtual meeting place.

    The integrated circuit and micro chip's impact on wave form control is a huge subject and takes some reading to see all the ideas involved. http://www.lincolnelectric.com/knowledge/articles

    I think you can find some of this info from Miller too.
    I spent several hours in conversation, over weeks, with both Miller and Lincoln design engineers before buying the current generation of welding machines in my shop. What I learned lead me to the decisions that I've reported here and on other metal boat sites. Lincoln's wave form controls in MIG are much more sophisticated therefore have greater potential for a wider variety of welds. Conversely, Miller's controls for TIG are much higher quality and versatile- and I bought with those conclusions to guide me.

    After many years of welding, with lots of different power sources and wire feeds, I agree with Fanie's remarks about the machine quality. Buy just above the best you can afford, and make the adjustments to your overall budget to get better power ratings, and more controls. Then grow into them as you learn more.

    cheers,
    kmorin
     
  2. Fanie
    Joined: Oct 2007
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    Location: Colonial "Sick Africa"

    Fanie Fanie

    Well Chris, there you have it.

    Kmorin, if you write the book I'll read it... !
     
  3. cahudson42
    Joined: Dec 2007
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    Location: Orlando, FL

    cahudson42 Junior Member

    I sure do..:) Thanks again all!

    Chris
     

  4. cahudson42
    Joined: Dec 2007
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    Location: Orlando, FL

    cahudson42 Junior Member

    P.S - at this point I'm saving my pennies for a Miller Dynasty 200 DX.

    Perhaps it took me too long to learn to WAIT before buying a tool, until it appears I'm not getting that much further up the learning curve before I do..

    I'm reminded of my purchase of the Festool TS55EQ circular saw.

    I once swore I would NEVER buy a Festool - overpriced. After all, whats the difference between one portable circular saw and another?

    Well, I found a tremendous difference. Our Woodshop has several hand circular saws - but now I'm always asked to bring in my TS55EQ for critical splinter-free perfect cuts. $500 - but a REAL pleasure to use. Worth every penny (No - I do not work for Festool)

    On the other hand, I am yet to be convinced that Festool Routers offer anything more than the Bosch 1617 - so I bought Bosch and am perfectly happy.

    I'm signing up for a TIG Community College course. In some months, I hope to report I bought the TIG equivalent of the TS55EQ.

    Thanks again everyone!

    Chris
     
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