Starting off and have some questions

[Well-D]

I would like to attempt to tig weld some box section tubes to form an octagon.

I have never done tig welding before so have some questions I hope you guys can help me with.

For welding box section with 3mm wall (mild steel) what settings would be best, my machine has three controls

Peak current 10-200A, Valley current 10-90% , Pulse frequency 0.5-2Hz,
Fall Time 0-5 S

There is also a Frequency shift switch with 3 settings. One has a straight line so I assume this means no pulse, the other other two shows a square wave, one at a higher frequency then the other.


Would I need to use filler rod ? If I simply cut the sections, butt joint them together can I simply just melt the two together or would I get better results using a filler?

 

[shenion]

Set the controls to DC (no pulse) Then just the peak current is used.

It can be done without filler. I always keep a bit of filler around, some MIG wire will do in a pinch (you can twist a few strands up if needed.)

 

[Well-D]

Thanks Shenion,

I guess that makes it a hell of a lot easier

What would be a good general purpose filler rod for mild steel?

 

[wyn]

An "A 15" grade of rod would be a good choice.
If you are welding 3mm thick box section then maybe a 2.4mm rod.

 

[shenion]

Most common is:
BS:2901 A15
AWS: ER70S-2
EN: 1668: W2Ti

 

[Well-D]

Thanks Wyn, Shenion.

With regards to the amps used, is there a general rule of thumb, so many amps per mm thickness of steel?