Plasma cutters/Tigs?

[Powermandan]

Ive noticed that some TIG sets have a Plasma cutter option on them.

Can this be done with all TIG welders providing you have big enough air compressor and a suitible torch?

Also what does "scratch start" mean?

Thanks in advance?

 

[Powermandan]

anyone?

 

[lorenzo]

I have no experience with these small dual purpose machines, but my assumption is that when companies try to build these small hy-bird machines there is always a certian amount of quality that is lost.

Scratch start when refering to TIG, is a method use to establish an arc. To scratch start the arc you would set the output directly on the machine.... Bring the torch down to the work and with caution try to graze the tungsten just over the work without actually touching the work. The arc should be able to jump the gap if you get close enough, you can also actully touch the work but this will chance contamination to the tungsten. The motion is similar to striking a match to ignite it. Once you establish the arc you will have to vary the heat but changing the arc length since the output is set on the machine.