2T vs 4T, a tack weld problem on my TIG

[carbon]

if the tungsten changes colour due to lack of shielding when it cools

Ignore this part, post flow controls the gas flow.

 

[carbon]

Maybe that’s the problem, when in 2T mode I need to lower the down slope as it would not switch off on the release

How long is the down slope time?

 

[addjunkie]

Maybe that’s the problem, when in 2T mode I need to lower the down slope as it would not switch off on the release

You still need some down slope to make sure you get a decent tack, argon flow is essential to protect both the weld metal and the tungsten electrode from contamination, oxidation, and damage while they cool

 

[doubleboost]

Ive never tried this but would have thought that the up slope and down slope would need to be very short for this to work with 2T

2T is just on and off no down or up slope that is a feature of 4T

 

[carbon]

Down slope is enabled in 2T on this thermal arc as shown in the manual

My thermal arc 250 also has similar operation with downslope in 2T

 

[Hitch]

Set it to 2T, HF, turn all up slope and down slope to 0 secs and try it. Leave a few seconds of post gas.

Arc should be ignited until you release the button.
The dial should simply adjust amps up/down id say.

If that works as expected, put it onto 4t. Press and release to initiate arc, press and release to stop.

It should stop immediately.

Introduce a second or two downslope and look at the effects.

Now some machines had additional functions on 4t, for example, pressing and holding whilst welding will drop machine to half power on some Migatronics for example, or a standard press and release will stop arc normally with whatever downslope is set.