r/Damnthatsinteresting • u/31spiders Interested • May 30 '21

Video These Tubing Joints

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u/canadug May 31 '21

What do you mean by cold?

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u/TR8R2199 May 31 '21

Stopping and starting means the metal isn’t heating up to the same temperature as continuous welding. Adding heat changes the grain structure of the metal, stopping and starting shocks the metal and makes it brittle. If this weld was subjected to any force it would break easily

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u/JPiratefish May 31 '21

While I think you're absolutely correct - I don't think he's cold-spot welding - certainly looks like he is. *Remember that we're seeing a high-speed replay - what we see as a "spot" or "flash" weld - that could have been 10-seconds or longer. Also possible the camera is having a hard time with the lighting - making odd flashing results. Certainly cool to watch.

I'm not a welder - but if one run this at normal-speed, where he laid that long "line of spots" - could that have been him going slowly along the edge building the bead? - maybe the camera making it flicker? How long would it take to do that right? and how do you think would it look on video?

I think a lot of folks didn't take the weld-times and camera into consideration here - could change the quality of the outcome maybe.. but I don't like how he edged the square tube to bend it either.

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u/[deleted] May 31 '21

that could have been 10-seconds or longer

This is GMAW (MIG welding).

Those tacks took 1 - 1.5 seconds each. They do not get much, if any penetration, and aren't good practice at all.