Welding Tips and Tricks

I've run many weld tests with 7018 in different amperages and continue to fail the test in the root pass. The cap bends out and is perfect with nothing in it. But the root pass will have literally 3 pin pricks of a hole along the sides of the weld. Very small little needle pricks along the sides. They used to be bigger but now I've gotten it down to very small holes.

I originally started running the root pass at 95amps but it had big holes. So then I went to 105amps and it had smaller holes. So then I went to 115amps and it had even smaller holes. And now I've run the root pass at 120amps and it still has very tiny holes!

I'm feathering the rod back and forth from side to side each time.The gap is an 8th inch gap. I'm now running the root pass at 130amps and the rest of the fill and cap passes at 105amps. The cap occasionally will have only 1 pinprick hole on the side but the root pass is having multiple pin prick holes every time.

How do I weld 7018 every time to pass a weld test.

I assume 1/8 7018? Typically if doing a 3g plate test with 3/8” plate, I use a 1/4” gap as is standard for that test. 1/8” gap for and 1/8” rod really isn’t enough for me at least. Either widen your gap a little bit or use a 3/32 rod. For 3g 1/8” 7018 I run about 110 amps and almost always have good luck

Amperage always varies by machine, lead length, travel speed, etc. so it’s difficult to say what is the “correct” amperage for you. Porosity is a symptom of poor fusion and/or contamination. If you’re welding plates, clean the backside and the edges as well as the front side. And the backing strap if you’re using it.

Make sure to wire wheel the root pass before you throw in a hot pass too.

Alright thanks. I will do these things. Yeah I saw that 1/4" gap was standard for this test with a backing strap. And I haven't been cleaning the mill scale so it looks like I've got to start doing that.

I passed the root pass today doing it at 130amps without grinding off the mill scale. But I think I'm going to make sure I just grind all that off from now on.

For my fitups today I definitely widened the gap. I welded out another plate test with all mill scale ground off and the root pass at 130amps just to be sure. Then I pulled it back to 105amps for the fill and cap. If you say you do well at 110amps then I believe it but it probably is for sure that you grind off all the mill scale. Even at 120 amps I was still getting pin pricks worth of holes in the root pass when I didn't grind off the mill scale. But today I passed the root pass with the mill scale on at 130amps so that's good to know too.

I'll post what my results are for these next few tests until I'm passing with flying colors every time.

Keep a tight arc. Long arcing, even a little, can boil the pool and create tiny voids or pinhole porosity.

Any time it matters; a welding test, an x-ray, etc you should grind the mill scale clean. Yeah, you can weld through it, but any amount of mill scale increases your chance of failure of an exam, especially an x-ray. In the field, you may not grind it because it’s not that critical and you surely can burn through it. But dang, if you’ve been struggling without grinding, grind it and pass the exam.

Alright I'm still failing the root pass and this time there is slag in it for sure. I've widened the gap and I know for a fact that it takes a weave to do the root pass. You can't have a 1/4" gap and not weave the root pass from side to side. So I'm going to start weaving it and see what I get.

You're right, it does take a weave.

These two Jody videos will hook you up.

https://m.youtube.com/watch?v=tC7PmksNDhY

https://m.youtube.com/watch?v=kblmdScflQU

MinnesotaDave wrote:You're right, it does take a weave.

These two Jody videos will hook you up.

https://m.youtube.com/watch?v=tC7PmksNDhY

https://m.youtube.com/watch?v=kblmdScflQU

I saw those videos earlier. The problem is that my instructors told me to do the very thing he said not to do which was to just barely go back and forth on the root pass instead of dwelling on the sides to ensure that you get proper penetration into the plates themselves. So for the past few times I've been doing it their way which they called a "nervous twitch" back and forth. But now I'm going to do a full on weave as shown in the video to make sure I get proper fusion on the root pass.

trainingGrounds wrote:

MinnesotaDave wrote:You're right, it does take a weave.

These two Jody videos will hook you up.

https://m.youtube.com/watch?v=tC7PmksNDhY

https://m.youtube.com/watch?v=kblmdScflQU

I saw those videos earlier. The problem is that my instructors told me to do the very thing he said not to do which was to just barely go back and forth on the root pass instead of dwelling on the sides to ensure that you get proper penetration into the plates themselves. So for the past few times I've been doing it their way which they called a "nervous twitch" back and forth. But now I'm going to do a full on weave as shown in the video to make sure I get proper fusion on the root pass.

I have no idea why your instructor wouldn't want you to pause on the sides of a weave. You need to since you go across the middle twice as many times as each edge gets hit.

I do the same as Jody.

How do you do the restarts? 7018 is prone to porosity at the start. You should restart about 1"above where you stopped, longarc it a bit back to your stop to heat up and tie in and weld over the start to burn the start porosity out.
But if the fill and cap are allways good your restarts shouldn't be the problem.

Do you clean the millscale after tacking the backing strap or before?

How many tacks on the backing strap? There should be no gap at all between test plates and backing strap.

Eric

You do NOT need to weave to make a proper open root pass for 3G using 7018 with proper penetration, It all depends on joint setup, rod diameter, machine you are using, arc you are keeping, VoltAmp curve of the machine and many many other factors.

Can you please make a short video of you putting that root pass from above at an angle around 45 degrees (through welding filter of course) and PM it to me?

I saw those videos earlier. The problem is that my instructors told me to do the very thing he said not to do which was to just barely go back and forth on the root pass instead of dwelling on the sides to ensure that you get proper penetration into the plates themselves. So for the past few times I've been doing it their way which they called a "nervous twitch" back and forth. But now I'm going to do a full on weave as shown in the video to make sure I get proper fusion on the root pass.

Your instructor gave you neither wrong nor right instructions. I was made to do the SAME using very small gap and very narrow preparation angle on both sides. So I would just push the rod inside and using up and down motions "gouge" the base metal then fill it with filler and push that material 'behind' to form the root side. It all DEPENDS on how your joint is set up and what exactly you are doing.

You do not need to worry about penetration into the plates 'sideways' themselves at the ROOT since the plates are grinded/milled/machined whatever and that place they are so thin you literally burn/melt through them and put "your" (aka filler) material in there to form the root. (Given that you have your current set properly, keeping the proper arc length depending on the rod size, plates preparation angle, Volt-Amp characteristic of the machine and DIG/ArcForce setting if available).

A friendly warning/reminder:

You have no idea how much the machine matters when it comes to SMAW welding. Difference in inductance/choke will give you the feeling of softer/harder/colder/hotter arc and much more....you need to be prepared to weld with other machines and tackle them out in the field. Even difference in cable cross section(gauge), length, ground clamp location matters a lot. Some modern inverter based power sources even give you a feel of smoother and softer puddle and metal transfer since the inverted power source is similar to a switching power supply that pulses very fast at 17-20 kilohertz ..now add a high frequency choke at the output and the mess gets even bigger....

Update:

I continued to struggle under the instruction of my teacher. He kept having me trying different things. So I watched Jody's video again and what stuck out to me was the whole "get it hot enough to keep a tight arc then, keep a tight arc." I ran some pad and thought that was my problem. So I flipped it up to 120-125 amps and just did exactly what Jody said about keeping a tight arc the whole way through and what do you know, I passed!

So thanks for everyone helping out and Jody. You think it's all these other things you must not be doing right but I was doing everything right except one thing. Once I made sure to keep a tight arc, I had no problem passing. That's pretty cool to know.