Quote Originally Posted by DaveO View Post
My recollection from the video (and the method I used) was to start at the middle of the hole on the lower plate and make circular motions outward, eventually reaching the perimeter of the hole and bonding to the upper plate that way. Then move the arc to the center to pile up some filler metal for the dome effect. I just went back to check the Everlast video- it's part 3, and the plug weld explanation starts at about time index 2:20. I was thinking it would be interesting to cut a plug weld apart to look at it in cross section.


It's a great series of videos, with about a thousand tips and tricks sprinkled throughout. Definitely worth watching... plus it's how you qualify for the current contest!
That sounds like pretty much the same method actually. The main idea is to make the circular motion around the perimeter and end in the center. The method that can fail is the one I mentioned previously where the person welding leaves the stinger stationary and just pulls the trigger for a second. That can leave the edge of the hole unwelded and cause insufficient penetration. I had a bunch of plug welds to re-weld after someone at my previous job hacked everything together on some 16ga stainless. If you followed what Everlast put in their video, you can be sure their method is correct.

I built a trailer that is nearly the same as theirs (many years back) and I always like to see other methods of construction. I didn't really know what I was doing (outside of the welding part) as I was a junior or senior in high school. It came out nice, but after all these years of welding and fabrication work, I look at it once in a while and think "Why didn't I do that a little differently?" Oh well, live and learn!