Tack weld

[Arc of steel]

As I’m just tack welding, what am I doing wrong, the small bolts seem to weld.But it doesn’t seem to penetrate the thick nut. It just brakes of . Some times when I do thinner bolts it melts the bolt

 

[Matchless]

the problem with small tacks using an arc welder is you need to warm up the rod so a very small tack may not get it going, you may need to run a bit more weld, and maybe the current is not set high enough for the larger bits, sorry not a very technical description, also remember to keep your stock of rods dry, like in the airing cupboard, it is 30 years since I arc welded but it was all I had once, would even weld on car wings with arc,