Welding Tips and Tricks

What can I do to prevent undercut?

I am welding 1/4” plate with 1/8” 7018. I started at 125 amps and kept dropping the amps until I couldn’t keep the rod from sticking. I ended at 109 amps.

Should I be using a larger rod? Slower speed?

I am still getting used to watching the puddle while trying to see where I am going.


Top pics is 125A bottom is 109A.


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less amps or faster speeds.

Even the bottom still has undercut. Move faster. You could use 160 amps if you move fast enough!

Great I speed up on the other side [emoji1303].


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jtornabene wrote:Great I speed up on the other side [emoji1303].

One thing is that speed will cause that, but with stick, WATCH THE PUDDLE.

You should have the electrode angled to blow the slag to the rear of the puddle, but keep the puddle fluid and watch the toes so it doesn't dig in. You wouldn't want to set stick on too high of amperage, but my guess is you're too slow if you're getting undercut.

OTOH, listen to someone else.

It looks to me like you are dragging the rod only, and that's fine. A good tight arc and watch the puddle "fill" the joint and just reach the top edge as you slowly move along. There is inconsistency in your travel speed showing, which is one of the hardest aspects of Stick: speed, motion, and arc length.

Don't be too discouraged, that's a very decent weld for someone getting started. But if you can, try to re-position yourself where you can always look back along the welding line to watch the puddle width, keeping your rod in the front of it. Be patient, let if grow, let it grow, let it grow Sorry, a bit of humor there. Point is: watch the puddle fill, then advance.

I like running hot, about 122-125 amps depending on length of work cables. Burns the rod well, allows me to move smoothly ahead and deposit fill metal fully and completely.

I won’t get discouraged, I’m just trying to learn as much as I can with each weld. I won’t have continuous welding projects to learn from.


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It looks like you're holding too long of an arc to me, it's more apparent in the bottom picture where you can see hints of porosity, as for travel speed you're definitely actually traveling too fast in some areas, but not so much in others, so I'd suggest aiming for more consistency with your travel speed over over moving slower or faster yet.

It looks like those are beveled plates from some of the under filled areas, if you're doing a groove weld then it is all the more sensitive to arc length and travel speed. and you also typically cannot fill it in one pass nor should you try.

The plates are cut at 90 degrees. I had the inside edges touching and tacked together.

So, I would have been better off doing a straight drag on the first pass and try to fill on the second?


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