New Welding Thread ?'s for beginners...MIG

[Matt@RFR]

Hey Josh. Yeah, welding bodywork is completely different than structural stuff.

To quickly answer one of your questions, no, structural MIG does not include individual spot welds, ever. That's just begging for a failure of one kind or another. I attached the only picture I have of one of my MIG welds. It's 1/8" mild steel.

To give you a real world example of how much spot welding would be frowned upon in the world of structural steel (bridges, buildings, etc.), anywhere a weld stops, the end of the weld must be ground down to the base metal before another weld is begun. And in multi-pass welds, starts/stops are staggered so they aren't in the same area.

,,,but I am not quite sure how to do the finishing welds after spotting every 6 inches or so.

Well, puting a tack every 6 inches is a good start. Then tack the joint every 3 inches. Then every 1 1/2". Then every 3/4", etc., etc..

Concerning the physical technique, once again we're talking about something that's pretty personal. It depends on your voltage/wire speed/wire size/stick out/gas coverage/metal cleanliness, as well as how well you can actually see what's going on in the roughly 1/2 second that the arc is on. I think most guys find that just pulling the trigger and holding the gun still works fine for them.



Penetration on 16-20ga and thinner should be complete, but for bodywork, I'm thinking it's not really required. Also, I'm not even sure the body guys completely weld the seems. You may want to check on that.