[Tim Hancock]

I would guess that the HF units will work....the 220 unit has more power in the description. We have an old large spot welder at work and it has adjustments for current, squeeze pressure and time of squeeze. I assume the HF unit probably does not have the same amount of adjustments, but once you get it set, the principle of how it works is the same. More expensive industrial units often have liquid cooled tongs and often come with different tong configurations to get around odd shaped parts, but I am sure you could easily make your own tongs from round copper bar if you needed a different shape.

You are the type of guy who could easily make one of these affordable units work for you. If I needed to make multiple spot welds on a major car restoration, I would not hesitate buying one of those. If you were going to use it everyday as a moneymaker, obviously you would want to buy something better, but for occasional hobby use, I say go for it.

Even on our industrial spot welder at work, we always do some test welds on exact material samples when setting it up and then try to peel them apart. The longer and harder you squeeze at a given current setting, the more penetration you get. It is really pretty simple.