Welding Question, Newbie Mig welder here trying to make some plug welds Options

[nathanxnathan]

I've been tig welding for the past 10 years and I think I'm alright at it, but I recently got a mig welder as I think some stuff I need to do on the car I need to go that route. I have a few questions...

So I got argon/co2 mix, I think 75/25, got some.023" wire.

First question, about plug welds, how big a hole should I drill? I saw this on the American Welding Society website

Per AWS D1.1

The minimum diameter of the hole for the plug shall be no less than the thickness of the part containing it plus 5/16(8mm) preferably rounded to the next greater odd 1/16". The maximum width shall equal the minimum width plus 1/8"(3mm) or 2-1/4 times the thickness of the member,which ever is greater.

For slotted holes it is the same as above except the length of the slot shall not exceed 10 times the thickness of the part containing it.

The minimum center to center spacing for plug welds shall be 4 times the diameter of the hole.
The minimum center to center of slot welds (traverse direction (this way II) shall be 4 times the width of the slot. Longitudinal direction (--) shall be 2 times the length of the slot.

The material I'm planning to use for repairs is 1 mm, so it's saying I need to make the holes 9 mm, which is 3/8 inch almost. —That seems really big given the size of the flange on most parts. Like it would be hard not to burn through the edge or both edges and make a mess to do that?

Other question is maybe a stupid question, but I find the torch this Hobart Handle 140 came with to be super awkward, like first of all it is gigantic coming from tig welding. Tig I always use a #7 or a #9 torch. This thing is like 2 sizes up from that equivalent it would seem. Secondly the button to weld is like a pistol — on the front/bottom of the torch, so it's really hard to weld on the bench. I have to put my elbow way up in the air to point the torch downward. I'm trying to angle it about 10º. So I get all shaky trying to do this, supporting it with my whole arm — I think my welds would be more controlled if a could weld with just my wrist, if I were able to support/rest my elbow on the table. If the button were on the top of the torch it would be more natural, to hit with my pointer finger. I guess a tig torch you can hold multiple ways, but the mig torch, I've tried holding it "the other way" and pressing the button with my thumb, but that's awkward, too. I'm not terrible if I use both hands — 1 to hold/stabilize it and 1 to press the button, but that seems dumb.

Here is a few practice welds, first pass at this. the right is me playing with voltage and feed, the leftmost is the 2nd , and then the middle last. Some of them is me trying with 2 hands, the better welds. Then the 1 hand, trying different holding positions I get off a bit. A few of them I was playing with "forging" the welds pounding them with a hammer to feel if they were harder than I'm used to as I've heard that about mig vs tig — they seem the same to me that way though.



The holes I drilled I are much smaller than 3/8, was going for something that seemed closer to what I'd want to do based on the typical size of a flange on most parts.

Maybe anyone has some insight on this?