Another copy and paste on here with a couple of video clip links around metal working.
I was asked the question by a mate, and am pretty certain I have not covered it fully, so happy for anyone else to add in more to enhance the response as a resource for anyone else, who like me learns as they go along.
Quote:
Originally Posted by sparkplug
So good to see truck time again :thumb2
As a complete novice welder - could you explain what the heatsink copper pipe was for?
I understand that it absorbs heat, but I don't understand why...
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OK. So half your reply lies in this video.
https://youtu.be/0Iik1ftVGXI
And then some more here.
https://youtu.be/qBJwngEimZU
Half or more than half the holes and repairs on this truck will be to older holes that may have been worked before, leaving the metal thin and tired.
The copper is essentially a non stick surface where the new weld (molten steel) is laid down in order to either fill, or repair, join fresh metal.
Sheet metal is actually quite thin and the first thing that happens is that you blow holes through it, making the hole bigger when a welders amps, wire feed is not set up right. Different jobs take different settings, like most things in life.
Where old rust has eaten at the steel, it becomes fragile, like lace, with holes mixed in with thin, compromised steel in between which mostly cannot be welded up.
So you cut away the dead metal, and make and shape up a patch and weld it back in.
When heated to melting point by the weld, the metal expands and pushes (WARPS) surrounding metal.
The copper removes some of the heat fast.
I also have a copper plate, 120mm X 50mm X 6mm used for larger flat sections. As well as some bronze “round bar” part of an old shaft.
The flattened copper pipe can be shaped and bent to fit in spaces like a door window frame etc as shown.
Many places (because rust happens in tight spots often as slow evaporation and crud collection ) you cannot get in with a heat sink, so a wet rag can work, or small repeated spot welds work better.
Hence it often taking time, a lot of time to do what seems like a small job.
Practice helps with speed too. But making a shaped panel or patch adds time.
Once welded, you need to grind back, inspect, and weld again if holes appear where you did not quite get penetration or filling.