Can you post up your settings SBK? How did you make the cuts? Also how do you do the backpurge? I rigged a second gas solenoid to control my purge line, which is essentially just a bit of pipe shoved down the highest point of the piece then wadded in with rags.
Thinking of re-jigging it to move the second gas solenoid so that its almost at the outlet of the purge pipe (its currently inside the welder), so trapping the argon in the pipe, as it took a while each time to purge the air from the line. I had a lot of stop starts due to welding stood up at the bench vice, had to keep re-positioning the work, and each time it took a while before I had the inside inert again.
Settings were 28 amps for the straight butts then 37 for the 2-1. using 1mm 308 filler No Pulse.
5lpm with 5 sec post flow no back purge on this as just dicking around, will post some pics later of my BP setup.
yes mate i use masking tape and then poke two or three holes in it with a 1.6mm rod to allow the flow.
depending on size of workpiece set gas to 4lpm for a couple mins then back off to 2lpm whilst welding.
You can check if the workpiece is fully purged by holding a lighter in front of vent holes if it goes out its got all the oxygen out.