Using 2T and 4T in TIG - Part 2
While 2T can work with the foot pedal in TIG units like the Power TIG 200 DV and Power TIG 250 EX, 4T is exclusively designed for the torch switch as it shifts the welder to the next phase of the weld cycle.In the case of the start amps, pressing and holding starts the arc, but releasing the switch signals the welder to step to the next phase, which is upslope. Upslope is presented as a unit of time (seconds). It governs the time the welder needs to ramp up the amps from the initial current (start amps) to the full preset welding amps. In 2T, when the switch is held this step is taken care of as soon as the start amp cycle is satisfied. This is automatically accomplished as the finger is kept down on the switch.This is simple enough. 2T with the torch switch is a great weld to spot weld and make short welds, and is less tiring than manipulating a foot pedal.As stated though in 4T, the torch switch is released to signal this cycle. Once the upslope has fully cycled, in 4T, the torch switch remains released (open) while welding. This is great for long term welding where holding the torch switch down as required in 2T, can be tiring or uncomfortable.This is a great tool to precisely manage the formation of the weld and controlling the heat. While some people prefer a pedal for maximum control, the torch switch settings reduces variability in the weld and between employees.