Thread: GP rod help!!

Originally Posted by Grahame Collins

Go here
http://www.millerwelds.com/interests.../pdf/Stick.pdf
to get a good explanation of electrode use and classification .

But that PDF says:

"For SMAW, the DCEP connection is used most often. It provides for the best penetration and bead profile. For this reason most electodes are made to weld with DCEP."

"Using a DCEN connection for SMAW will result in a narrow bead with little penetration. This connection works well when welding on sheet metal or for hardsurfacing electodes."

Which seems to be the complete opposite of what was said earlier in this thread

Oops!!
I referenced the link specially for the electrode classification and code number flux and polarity listings.

I did not bother to read the full text.MY bad!!

I don't agree with it states either. I reckon theres a typo somewhere.Most work with these electrodes is on DC Electrode - A few passes with electrodes on both polarities will quickly tell you what will suit you best.

My old boss used Lincoln 12 & 13's and if welded carton after carton of the things on electrode negative,with out problems.

In any case that should be the way that everyone approaches a welding job.Variable inputs -like power supply change from time to time .

To this day,I still set up and run a practice bead on scrap to prove the electrode and check the settings.

Using a quality inverter machine capable of AC/DC ,my preference on 4112 &13,s is mostly AC.

In the end,it is what suits the operator.Try both and find what suits,no big deal.

Grahame

Originally Posted by phelum

I don't think this is right. Current = electrons. If you have 70 amps you have a certain number of electrons per second regardless of direction or cathode surface area.

You're spot on when you say that 70A defines a certain number of electrons per second but there are a lot of other factors here as well. When you set your welder at say 70A that doesn't define the actual current that will flow. It's just the maximum. Other things like resistance, earth bond, arc length and electrode area have a bearing on the actual current.

Just like when you're selecting cable for a piece of equipment the cross sectional area has a bearing on the amount of current that can flow. You can't throw 100A down a 1sqmm cable. You'd need at a guess about 25sqmm.

As a matter of interest I just hooked up a clamp meter to the power cord on mig and changed the polarity leaving everything else the same. It's definitely using more juice when the electrode is positive. Not heaps more but it's noticeable.

Interesting

Originally Posted by Grahame Collins

A few passes with electrodes on both polarities will quickly tell you what will suit you best.
.
.
In the end,it is what suits the operator.Try both and find what suits,no big deal.

Absolutely - I should go and do some tests just to see what the actual difference is with the welder I have and the particular rods I use.