gap size

[grumpygramps-2007]

going to bite the bullet & treat myself to a mig from weldequip. i,ve already asked some questions & i,ve got one more. when you butt weld do you always have a gap & what size is it. somebody told me its same as weld wire but i,ll wait to hear from you guys.

 

[malcolm]

The purpose of a gap is to increase penetration without increasing volts or wire speed. Penetration can further be increased using a V prep (see http://www.mig-welding.co.uk/arc-flat-joints.htm )

So whether to have a gap or not depends on whether you want more penetration. You might want no gap at all up to 2mm steel, a gap in 3mm, and a V prep in 5 or 6mm steel.