I may be missing something here but why can't we disconnect the wire feed, screw in a tungstone tip and happily use our MIG welders to TIG - only on steel, and only scratch start but for the occasional TIG welding why not?

Let me know how you get on.

I've tried it - even with the lowest current and pure argon it almost instantly burnt away the tungsten. Came to the conclusion that the polarity and waveform were probably all wrong for TIG and gave up. If you could come up with a way of making it work tho' I'm sure there'd be a lot of people wanting to try it.....

I thought that MIG was DC, if you want to up the power you up voltage/current whereas TIG is a square waveforem; to up power you increase the mark/space ratio.

I thought one was constant voltage while the other constant current. don't which way, tho.

dave

Rats thought it would be too good to be true

. I think it would be documented somewhere if it would work. If you forget to turn the wire speed on just see how quick the wire burns back, your tungsten is going to do the same. Combined Units that do mig and tig like the Miller machines are very expensive, probably for a reason.

Don't forget if it is DC, then for TIG welding the ground should be +ve and the torch -ve, or you will burn away the tungsten.


[Edited on 11/4/06 by JohnN]

right..
mig and dc tig are both dc- direct current
mig has a nominal voltage of 35 volts dc - tig has a nominal voltage of 80 volts dc.
mig is negative earth and tig is positive earth.

the big thing is the voltage tig requires a higher voltage as the arc has to be maintained across an open arc shielded by argon. that is why you cant tig with a mig power source.
pps you can stick weld with a mig..
hope this is clear
dean