I have been using mig/mag and stick for many years without any problems. MIG rust repair jobs on cars with 0.5mm sheet metal. At my job i did a lot of production MIG welds. And i use the soldering iron daily. This gave me the confidence that TIG welding stainless steel would not be such a big issue... Boy was i wrong.
Some really important things i wish somebody told me:
- Cooling. To prevent black welds, glowing red workpieces and black sugar like colliflowers on the backside. Cool the material with thick aluminium chill bars that fit precisely and press them down tigthly with all the clamps you can fit.
- Grind the tungsten into a thin sharp point. Especially if you have to weld into a 90 degrees corner. And make sure you put the tungsten as close as possible in the corner.
- Make sure the surface is clean, everything fits tightly together, your hands are resting on the table and do a practise weld(machine off) so you know you can reach the whole weld smoothly.
- Practice some welds without adding wire first.
Don't bother with big glass cups and backpurge, get this above stuff down and work from there. Get very thin 316L welding wire, the thinner the easier, some wire from an old 316L MIG spool works perfect.
Withouth using the tips my welds looked like this..
