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Undercut

Posted: Mon Aug 31, 2020 3:27 pm
by jtornabene
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125A 7018 1/8”
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109A 7018 1/8”

Should I be using a larger rod? Slower speed?

I am still struggling to watch the puddle while seeing where I am headed.


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Re: Undercut

Posted: Mon Aug 31, 2020 8:35 pm
by Poland308
Slower speed. Looks like your really close.

Re: Undercut

Posted: Mon Aug 31, 2020 10:17 pm
by jtornabene
Thank you.
Would rod angle make much difference?


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Re: Undercut

Posted: Mon Aug 31, 2020 10:20 pm
by Oscar
I'll go out on a limb and say pretty much everything makes a difference. You have to practice any and all "questions" you come up with, so you can see the effect.

Re: Undercut

Posted: Tue Sep 01, 2020 7:42 am
by Poland308
Yes rod angle on 7018 is pretty forgiving you can push or pull it. It’s an all position rod. But arc length is much more critical to getting it to run right. Most common things I’ve found that create undercut with 7018 are, 1 not getting off the mill scale, 2 to fast of travel or not holding the sides long enough if your weaving, 3 long arc, 4 way too hot of amps for the thickness of metal or position of weld. It takes a little bit to get used to looking through the slag and trusting that the weld is doing what you think it’s doing. How thick was the steel? And was it beveled, and roughly what degree of bevel? Was it an open root , and was there land.

Re: Undercut

Posted: Wed Sep 02, 2020 2:44 pm
by jtornabene
Poland308 wrote:Yes rod angle on 7018 is pretty forgiving you can push or pull it. It’s an all position rod. But arc length is much more critical to getting it to run right. Most common things I’ve found that create undercut with 7018 are, 1 not getting off the mill scale, 2 to fast of travel or not holding the sides long enough if your weaving, 3 long arc, 4 way too hot of amps for the thickness of metal or position of weld. It takes a little bit to get used to looking through the slag and trusting that the weld is doing what you think it’s doing. How thick was the steel? And was it beveled, and roughly what degree of bevel? Was it an open root , and was there land.
The steel is 1/4” plate cut at 90 degrees and is an outside corner weld.
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Thanks for the responses.


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Re: Undercut

Posted: Wed Sep 02, 2020 2:45 pm
by jtornabene
Poland308 wrote:Yes rod angle on 7018 is pretty forgiving you can push or pull it. It’s an all position rod. But arc length is much more critical to getting it to run right. Most common things I’ve found that create undercut with 7018 are, 1 not getting off the mill scale, 2 to fast of travel or not holding the sides long enough if your weaving, 3 long arc, 4 way too hot of amps for the thickness of metal or position of weld. It takes a little bit to get used to looking through the slag and trusting that the weld is doing what you think it’s doing. How thick was the steel? And was it beveled, and roughly what degree of bevel? Was it an open root , and was there land.
The steel is 1/4” plate cut at 90 degrees and is an outside corner weld.


Thanks for the responses.Image


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Re: Undercut

Posted: Wed Sep 02, 2020 4:00 pm
by Louie1961
The shape of your ripples is the dead giveaway for me. Vee shaped ripples always mean you traveled too fast. Slow down, and give the puddle more time to fill in. If your weld is horizontal, pause a little longer on the top side of the weld and add more metal there to fight the pull of gravity.

Re: Undercut

Posted: Wed Sep 02, 2020 4:24 pm
by Poland308
If it’s only 1/4 inch metal I’d be running 3/32 at about 80 amps.

Re: Undercut

Posted: Wed Sep 02, 2020 4:26 pm
by jtornabene
Poland308 wrote:If it’s only 1/4 inch metal I’d be running 3/32 at about 80 amps.
Would you expect to make two passes to fill it with 3/32?


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Re: Undercut

Posted: Wed Sep 02, 2020 4:34 pm
by Poland308
No one pass.

Re: Undercut

Posted: Wed Sep 02, 2020 7:44 pm
by jtornabene
Single pass with 3/32 7018. According to my amp gauge (which I think is wrong) I’m running 106 amps. I can’t keep from sticking striking the arc below that. I held longer on the top to try and fill in.Image


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Re: Undercut

Posted: Wed Sep 02, 2020 8:19 pm
by Poland308
Yeah your amp gauge is off looks like about 40 amps off. Give it 5 or 10 more and that weld bead will smooth out. Side note. If your long arcing then you need more amps then someone who holds close. But long arc usually leaves lots of spatter. I’m not seeing that. Slow down just a bit more with the same settings .

Re: Undercut

Posted: Wed Sep 02, 2020 8:57 pm
by jtornabene
Poland308 wrote:Yeah your amp gauge is off looks like about 40 amps off. Give it 5 or 10 more and that weld bead will smooth out. Side note. If your long arcing then you need more amps then someone who holds close. But long arc usually leaves lots of spatter. I’m not seeing that. Slow down just a bit more with the same settings .
Image
5 more amps and a little more patience. Holding the top twice as long as the bottom.


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Re: Undercut

Posted: Wed Sep 02, 2020 9:47 pm
by TraditionalToolworks
That looks much better!

Re: Undercut

Posted: Wed Sep 02, 2020 9:50 pm
by Poland308
Definitely better. Just more practice from here.

Re: Undercut

Posted: Wed Sep 02, 2020 9:52 pm
by jtornabene
Thanks for the tips! I have struggled without any mentoring other than you tube.


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Re: Undercut

Posted: Mon Sep 07, 2020 10:14 am
by BugHunter
Have you ever considered a wire brush on a grinder and remove even the slightest bit of all that dirt you're welding through?