Great idea will give it a go thanks!I learned the answer to this today. More amps. Thickest peice here is 3mm so I started practise at about 90A, then I reread the ac tig guide thread. Saw the +50% rule for tacking, and stuck it upto 160a, liked the result and left it at that. The big heatsink was needed or it'd be a melty mess, bead flowed nicely.