Also, don't open the gas supply too much. Normally 10 litres a minute is plenty.
Most MIG gas regulators have a green patch between 10 and 20 Lpm ( some show a lot more)..... so people tend to set it in the middle.
Not only does this waste gas, but with a small torch, the gas exit speed is to high, and it causes "wind" which actually sucks air in behind it...... causing shielding problems.
The natural reaction to this is to turn the gas up, when in fact the fix is to turn it down.
Only when I can't avoid a breezy day, might I turn it up, and always setup the weld position so the torch is pointing towards the ambient air flow.
With car panel and structural work I am often doing plug welds, through a 5 or 6mm hole (depending on material thickness) in the top layer. This replicates the original spot weld quite well, and you should avoid the tendency to weld to much.
Most MIG gas regulators have a green patch between 10 and 20 Lpm ( some show a lot more)..... so people tend to set it in the middle.
Not only does this waste gas, but with a small torch, the gas exit speed is to high, and it causes "wind" which actually sucks air in behind it...... causing shielding problems.
The natural reaction to this is to turn the gas up, when in fact the fix is to turn it down.
Only when I can't avoid a breezy day, might I turn it up, and always setup the weld position so the torch is pointing towards the ambient air flow.
With car panel and structural work I am often doing plug welds, through a 5 or 6mm hole (depending on material thickness) in the top layer. This replicates the original spot weld quite well, and you should avoid the tendency to weld to much.