What is 2T/4T? What does it do?

[performance]

Frequently, we have a lot of guys (and women) calling in sometimes afraid there is something wrong with their machine or that there is a problem with their torch...

Usually a quick rundown of the controls discovers the problem: the unit was being used in the 4T mode and it either had the foot pedal attached or the torch would not develop full heat.

The 2T/4T literally stands for two touch or four touch operation.

In 2T mode, operation is fairly simple. All you need to do is EITHER use the foot pedal or disconnect it and connect the torch switch cable to the amphenol connector in the front of the unit. You CANNOT use both simultaneoulsy, mainly because there is only one connector. You must decide to use either the torch switch to activate your current flow or the foot pedal. Activating the torch switch in 2T mode is simply a process of pressing the switch and holding it down and the machine will operate at the preselected settings on the machine panel. This is very good and simple operation of the machine for new beginners and tasks where the required amperage can be preset if it is required.

The 4T setting is a little more complex as you have control over the stages of the welding cycle and when each stage begins and ends. To operate, simply press and hold the torch switch. The preflow and start current should initiate. During this time, you are still holding the switch. When a puddle begins to develop, you can release the switch and the torch automatically begins the preset upslope cycle until it reaches full operating amperage. To terminate the weld, simply touch and hold the switch again and the torch will begin the downslope cyle and continue to the end current phase which will allow you to precisely fill the crater with out overmelting. Filling the crater is important to preventing the weld from shrinking and cracking upon cooling. To terminate the arc, simply release the torch switch and the arc will end and the post flow cooling of the torch and weld will begin.

4T operation is very precise and controlled so that welds may be made perfectly without constant manipulation of the foot pedal to make welds. Honestly , many people who learn to master this operation, never go back to the pedal. A perfect example of a practical application is for welding car frames and roll cages where a foot pedal will not fit or be practical to use. Many people think that in this situation a slider rheostat torch control is the way to go...But generally, precise amp control is not easy. So, the unit may be set perfectly before hand to operate at optimum amperage with only a touch of the switch.

Whether it is foot pedal, or torch switch operation, it must be remembered that the foot pedal functions ONLY in 2T mode. If you are experiencing problems with strange behavior of the torch or the pedal, check to see what the machine is set on and whether you have the correct cable plugged into the unit.

[jtybt]

Thanks, I needed that. I can do more experimenting.

[Gary]

Hey Mark, or anyone else that might know.
I was down and tried out a 256 at Mikes today , brought it home and have not used it but for a few beads at Mikes place . On the 4 T setting I was holding the switch trying to get a puddle to form but it did not come up to full amps then let off and it would still not come up to full amps to puddle , but when I hit the switch the second time to start the down slope it would come right up to amps the shut down. (arc not the machine) . Like I said I only tried it a few minutes with the 2T and once the amps where right it welded great.
We only put a few seconds for ramp up and ramp down so it should have come up to full set amps but it didnt until I hit the switch the second time..But as soon as I hit the switch the second time it came right up like it should..I do have to say ,,,nice machine good puddle and hot when set right..
And like I said I have not had time yet to get time on the welder yet, but I am going to try and set it up this weekend and get it welding as soon as I finish a small job that I have to finish tommorrow, I dont want to try and learn a new welder on the last few pieces I need to finish for the job to go out on sunday
Thanks
Gary