If a person is good enough, spots about 3/8" long are the bomb,

My son layed these down. These are typical for him but he is better than me.



A flux core machine will work, you will need to clean it up all the time though.

In other words, you will need to clean ALL of the slag off the previous welds before welding on to them with new welds.



These are "good ones" for me.
Notice how the spots kind of overlap each other.

 

i use small tacks. keeps me from blowing thru and warping the metal.

 

Oh ****, here we go again,

I dont think I have any pics of the backside, but the penetration of the welds is fine.

I havent finished (painted & bodywork) the fender yet so maybe I can get some pics tomorrow if I feel the need to....

 

sorry JMD. i forgot who i was dealing with. i editing my original post.

 

Flux core is not for smaller metals. Flux core gets excellent penetration, generally for the same voltage input to the welder, flux core will get about twice the penetration over MIG. So it's great as a 110v unit like I have, for welding 1/8" on up, but under 1/8" it takes a fair bit of skill, and when you get into the thin stuff, it's almost always overkill. That's where MIG and TIG really shine, is on the small stuff, since it makes small clean welds, especially TIG.

Trying to weld body panels with flux core will require good skill. But I generally would only recommend flux core for structural type stuff, subframe connectors, chassis repair and so on.

 

Ive always had a better result with TIG over MIG

 

TIG is a better welding process with much more control and can weld pretty much anything, but it's only drawback is that it requires a considerable amount of skill to do properly, especially when you start getting into the more exotic metals. That's the only thing that makes TIG not so accessible to average Joe. But TIG can weld paper thin stuff, trust me. I've TIG welded stuff in the 20-something gauge range and it works very well, excellent control over the heat.

 

Of course TIG is superior and I actually found it easier to learn to TIG than I did to MIG. This was probably because I did a lot of gas welding and soldering when I was younger, so feeding the rod and managing the heat seemed very natural for me.

There will probably never be any doubt that TIG is a superior process. The problem in the real world, however, lies in the fact that most hobbyists can more easily afford to gear up with MIG than TIG.

 

i'm the same way. i learned TIG first and can get great penetration and make nice little coins with a TIG. i can weld razor blades together. but give me a MIG and it looks like a 5 year old did it. but that's the difference between the two processes. after a couple years of experimentation, i can do a decent MIG job on sheet metal now..

as for switching to solid core wire, you must use CO2 or Ar/CO2 blend gas. solid core with no gas doesn't work. everyone who uses gas has forgotten to turn it on at some point. you get massive blow through, lots of splatter, and everything turns to rust.

 

The biggest problem with flux core IMHO is the mess. The mess just isn't acceptable when leap frogging around on sheet metal because you would either have to clean up after every spot, or weld over it, which will be pinholed.

75% Argon with .025 wire is ideal, but .030 will work okay.