Since the topic of mig-S, the welding process that many folks want & enjoy using, comes around for discussion throughout the years I came across these videos that show the good, the bad, & the ugly of lack of fusion with mig welding and thought it might just help someone. There are a ton of videos out showing mig-S welding BUT many are nothing more than pretty-pass junk welds with no fusion!

I actually saw a far better looking mig fillet weld similar to this break apart as I’ve described in another thread just by tossing it on the shop floor. Notice this seagull poop was welded on 1/4” as I’m sure an extreme example.
https://www.youtube.com/shorts/uZEqC8F6Vrg?feature=share
[video:youtube]https://www.youtube.com/shorts/uZEqC8F6Vrg[/video]

The help video-
https://youtu.be/lSNXTgmNbxk?si=nl0SlcXWmTxMnkwl

BTW, on an added note. Folks asking about volts & amp settings when mig welding need to remember, stick-out of 3/8” is the very best. The length of stick-out has EVERYTHING to do with your amps! If you have an amp gauge on your machine have someone watch it while you weld and purposely change the length of stick-out. You’ll be amazed how it will change your amps and the negative effect it has on your weld. Lack of fusion, seagull crap for a bead, and increased spatter.

If you can’t see your puddle very well with a 3/8” stick-out, buy a tapered nozzle and turn your gas down a little, or reposition your body but maintain the 3/8”! Do not do anything that brings the contact tip out beyond the nozzle so you can see better.

IMO the hardest part of fab work is controlling warpage. I see the pick for that video and think steel will be twisting big time.

Yup, but because it’s mig-s, the heat input is the lowest of any of the normally used welding processes so there is far less warpage making mig-s a good choice for fabricating thinner material. The weld bead still cools & contracts from the outside to the center but with such a narrow heat affected zone, there is far less warpage.

Mig just stands to or metal inert has. The process is gmaw.