Spot welding help

[tomfc]

Ok so I have managed to get hold of a spot welder, it's a trangle 240v spot welder.

It has a lever on the top which pulls the copper arms together and a black button.

When I clamp the arms together and pull the black button back it powers up, how long should I be keeping the power on for say joining two 1.2mm panels?

Also any other useful advice would be great

 

[Paul.]

Spot welders normally have a timer on them as well, weld time will depend on the power of the welder, material thickness and type, the tip geometry and the pressure, this chart from the back of mine may help you.

 

[Robotstar5]

Once you have welded the material, slide a chisel down the side of the weld and tear the 2 plates apart, the sign of a good weld is hole about the size of the weld torn out of one piece, known as "pulling a slug"

 

[Bill Edwards]

A bit of practice at varying the power and time. Too much power and time leaves wrinkles as the piece gets too hot.

 

[Jim Davey]

Let the arms and machine cool down regularly, 10 spots in a row on a cheap handheld is usually enough to make the arms roasting hot, and it takes a surprising amount of time for the heat to leave such big chunks of copper and iron.
Also, make sure the tips come together in perfect alignment and the flats are nice and small, say 3mm across, you don't want huge flats on the tips as that takes a lot more energy to weld with a larger surface area.