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Welding 101 and 102

25K views 57 replies 22 participants last post by  dcb 
#1 · (Edited)
THIS ARTICLE IS NOT MEANT TO BE USED IN PLACE OF STANDARD SAFETY RULES AND REGULATIONS. IT IS A SUPPLEMENT AND INTENDED TO BE USED IN ADDITION TO THEM.

I first learned to Arc weld when I was 9 years old. I am now 61 and have learned a few things along the way. I wish to share some of these things and hopefully have you share yours as well and ask questions.

I do not profess to be the world's own expert in welding, I do however have some knowledge that might make your next project easier.

My father owned a large steel fabrication business. I spent several nights per week, weekends, holidays and summer breaks there. I progressed from floor sweeping to machinery operation to layout and through every department in the shop until I could pinch hit for each station.

Later, I was a Union Ironworker for 23 years, a crane operator and a community college instructor before going into a full time racing career.

Those early years in the fab shop were always a constant source of skills and knowledge to fall back on and have served me well.

Welding, in one form or another, has been around since metal was first used. It generally consisted of heating two pieces of metal and bludgeoning them until they were one solid mass.

Metal is just one layer of molecules over another, all interlocking, forming a malleable lump. Heating and beating reforms that molecular bond between those separate pieces making them one again. The actual "weld" area is one molecule deep.

Along came the industrial revolution and with it, electric trains and trams. After the wear and tear of the tracks caused pits and lumps, they needed to be replaced or resurfaced. Grinding would remove the lumps, but the pits needed filled in. They learned that by attaching a heavy copper cable to the overhead DC service cables and using an iron bar for the sacrificial electrode, they could heat the pitted area and melt the bar into it forming a patch. A little grinding and the track was good again. Arc welding had been invented.

Prior to that they used Oxygen/acetylene welding. Again, heat the two pieces until molten, add a filler and cool to reform the molecular bond. It was strong but was time consuming and costly. After the advent of electric arc welding, it was relegated to mostly smaller/thinner items.

The early arc welding process was really crude, it consisted of arcing the metal with a bare iron rod and hopefully melting them together. It soon was learned that the welding current polarity was a major factor in the successful result of the job. On most welding, DC current was used, but under some conditions AC current would work too.

AC current was useful in dirty environments. It performed a "cleaning" effect, which was useful on rusted materials.

DC current, though, was the clear winner when a stable, controllable process was desired.

DC reverse polarity (work piece - and electrode +) was outstanding on heavier pieces as the direction of the arc would crater(and fill in)the work piece allowing a stronger weld without much edge beveling. (Most stick welding uses reverse polarity)

DC straight polarity(work piece + and electrode -) would do the opposite. It would not crater much and allow the filler to "pile up" and thereby allowing an arc weld on a much thinner piece than was normally the case with reverse polarity welding. (Most wire feed welding uses straight polarity)

Any welding process is dependent on the joint design, fit up quality and cleanliness. Take your time, do it right. (sticking in a piece of rebar or an old bolt as a spacer or filler is a silly/ childish practice. "Just say no!")

Unfortunately, I see a lot of sad, childish things on even nice cars. It puts the whole thing into question as to quality and safety. It does not represent the EV community very well either.

(End of part one)
 
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#57 ·
This is attractive Welding 101 incredible work lower than around 1-4 and at low speeds it is some of the period spirits moderate or quick. Is that typical for these welders? I trust I've set it up effectively, in that it's as well-lit as it can be deprived of slipping or unspooling.
 
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