When to use AC and when to use DC

Will somebody explain when to use AC and when to use DC.

I know a person that is wanting to sell a Lincoln AC/DC that was used very little and he wants $150. Is this a good buy?

Thanks

Regarding magnetic fields, DC polarity being constant will build a magnetic field that remains constant. This can cause arc wander or arc blow in tight enclosures. Changing to AC polarity eliminates the field each time the current alternates.

As stated, some electrodes are only designed to operate on a given polarity setting while others, such as the airless gouging electrode, will operate more efficiently on one than the other.

DC provides a very stable arc compared to AC thus is much easier to control metal fusion. Theres less weld splatter with DCRP. Being DC has been the most popular choice of welders for many years there is a vast electrode selection where thers a very limited selection for AC.

I personally like DC over AC but I also quit professional welding several years ago and have a old Lincoln AC buzzer that I still weld with for all my home use. If the buzz box ever gives out then I would buy a AC/DC to replace it with. To run out and replace a AC machine with a DC machine is a waste of money other than one for $150 smackers. If the machine welds good then I would pay $150 for it even tho I don't need it.

I would also buy 50lbs of Chemtron 7018 and Lincoln 6010 as those are the two finest DC rods made and will make 99% of the welds that a professional/home user needs but I also could get by on just Chemtron 7018.

T_Bone

You can weld the same with both rods. 6011 has it's own place tho and thats welding galvanized. You can use 7018 with grinding off the galvanize but it's very difficult to use with the galvanize left on. 6011 will clean the galvanize off as you weld. 6011 can also be used on AC.

I'll assume you were talking about the 6010 that I refferenced in the above post. With 6010 it's much easier to run a open root weld than with 7018 although 7018 can be used for a open root weld. You can also get deeper penatration with 6010 than with 7018.

If I only had one rod choice it would have to be 6010 as it also does well on galvanize when on DCSP.

All rods have there special place. 7018 is such a good all around rod and looks well when your done. 7024 is great for welding on the bench on flat weld joints and is very smooth and a very fast rod. The problem 7024 has for field work is it's restricted to flat and horzontial welds.

T_Bone