Arc blow in G3 test plate

[Shield Arc]

Actually 1/4" gap is easier. Generally the plates are gaped the same distance as the rod diameter, which gives you very little room to move.

 

[dcyrilc]

Actually 1/4" gap is easier. Generally the plates are gaped the same distance as the rod diameter, which gives you very little room to move.

That makes sense. Most of my reading has been oriented toward mig. That might help explain why that gap seems so big to me.

 

[Shield Arc]

1/4" gap with a backing plate I'd run it with two passes, (one up each side overlapping) because I'd be afraid of burning through the backing plate on vertical up.

For open root I like 5/64" gap with 3/32" root face / land, with 1/8" 6010.

 

[dstig1]

Actually 1/4" gap is easier. Generally the plates are gaped the same distance as the rod diameter, which gives you very little room to move.

:confused2: Easy for you to say!!:laughing: With the 7018 rod having such a thick flux coating, there really isn't any room to move other than just a little wiggle here and there (usually due to bad grinding on my part). 1/8" 7018 is close to 1/4" OD, when you include the flux. It is one pass for us on the root, and no issues blowing through the backer that I have seen. We're running 110-115A. My biggest issue is that the bead won't fully lay down (humps a bit in the middle) so I get trapped slag at the edges that I can't get out (or can't see).

 

[Shield Arc]

My biggest issue is that the bead won't fully lay down (humps a bit in the middle) so I get trapped slag at the edges that I can't get out (or can't see).

Oh yeah! That is called wagon tracks. Bad business if you're not allowed to use a grinder. I never ever took a plate test where I could use a grinder.

If you're getting wagon tracks, you need to work on your rod angle, and travel speed. If everything is correct you should be able to just drag the rod up hill with very little movement. For my root pass with 7018 I'll have the rod about 5 degrees down angle, (85-degrees to the plate). When doing this if I get in trouble, I'll start making a J motion. Run up one side, back down into the puddle, hold until it fills, run up the same side again, repeat as many times as necessary.

 

[dstig1]

That's what the instructor told us too - about 5 deg rod angle. I try to maintain it, but sometimes my attention drifts as I'm focused on controlling other things and the angle increases until I catch it. We've used the grinder as needed, but this isn't any kind of an "official" test. It's just him trying to teach us good procedure. With the amount of time these things take to set up and run, it isn't worth it to pile more weld onto bad weld.

Also it's hard to see what is going on with the heavy 7018 slag.

You mentioned speed - is this usually a too fast or too slow issue causing it?

Thanks!

 

[Shield Arc]

You mentioned speed - is this usually a too fast or too slow issue causing it?

It's a too slow, and too cold kind of thing.

Here is a vertical up root with 7018, I just stuck the rod in and drug it up hill, next to no movement at all. See how the heat started to effect the weld at the top?

 

[dstig1]

Jeez! Could you make me look any worse? :laughing: "Yeah I threw these two plates at the wall and stuck a rod in there while I was painting and taking an online class, just for sumtin' to do..."

Seriously I appreciate the advice. I will try more amps and faster movement. What amps was this at?

Oh and you keep a bin of beveled plates on hand just for the occasional TBN thread when you need to spank a newb?

 

[Shield Arc]

Advice is free, I don't mind helping at all, a little pay it forward thing if you know what I mean.
If I gave you an amp number I would just be guessing, so lets say 115.

I have an Ellis 1800 saw, takes me just a couple minutes to cut the bevels, and tack up a plate.

 

[dstig1]

Well if you're running in the same general amp range as I am, then I must be running too slow, plain and simple.

I appreciate the help. I have the same feelings and try to help others where I can. Right now I can help lots of weldors on how NOT to do a G3 vertical up test plate...