Tig Welding Chromoly Question Taking A Second Pass?

Hi everyone. I have been doing a lot of practice tig welding with .040 er70-2 filler rod and .035 wall 4130 tubing from Aircraft Spruce. It has been a long steep road but I am finally getting a handle on it. I have been using pulse settings (80A peak, 15 base, 2 pulses per second) with the lay wire technique. My torch is a CK130 with 1/16" 2% lanthenated tungsten. My welds are looking better on the first pass. I can make them look better if I take a second pass adding filler rod in the thin spots. I am still practicing and my goal is to get it on the first pass but I was wondering if it is a bad practice to go over the welds twice?

Fernando Carcao

A lot of builders will run a fusion pass and a filler pass on titanium. On anything else, it's best to weld it once and be done with it.
Like you said, work on getting it right on the first pass.

I’m getting there. I have been trying to develop a sequence in order to be more consistent. I can make it look much prettier if I go over it twice. I can see how going over it twice can be a poor practice.
I’ll keep practicing:
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Nice work in committing to practice.

How high is your amperage set? One of the things I noticed when I was an instructor at UBI is that most beginners are afraid of using too much heat and avoid it by going slow and using lower amps. A large portion of your beads are dull and grey, that's a sign of too much heat input. It might seem counterintuitive, but if you set your machine up to 150A, go deeper into the pedal and move faster, you'll input less heat into the joint and get better flowout of the filler. You'll probably blow open a few holes, but filling holes is part of the journey and you might as well become an expert at that before you start welding frames. Be sure to practice some 60° joints too

The next time you're picking up weld rod for practice, get a little ER70S-6 and give it a shot. I've always felt that S-2 felt really grainy when trying to push a lot of rod into a puddle (like in an acute part of a joint). The S-6 seems to flow out a little better without having to push on it as hard. Don from Anvil turned a lot of builders on to Weldmold 880T, which flows out very nicely but costs a bit more than the ER70 rod.

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Originally Posted by VertigoCycles

Nice work in committing to practice.
We
How high is your amperage set? One of the things I noticed when I was an instructor at UBI is that most beginners are afraid of using too much heat and avoid it by going slow and using lower amps. A large portion of your beads are dull and grey, that's a sign of too much heat input. It might seem counterintuitive, but if you set your machine up to 150A, go deeper into the pedal and move faster, you'll input less heat into the joint and get better flowout of the filler. You'll probably blow open a few holes, but filling holes is part of the journey and you might as well become an expert at that before you start welding frames. Be sure to practice some 60° joints too

The next time you're picking up weld rod for practice, get a little ER70S-6 and give it a shot. I've always felt that S-2 felt really grainy when trying to push a lot of rod into a puddle (like in an acute part of a joint). The S-6 seems to flow out a little better without having to push on it as hard. Don from Anvil turned a lot of builders on to Weldmold 880T, which flows out very nicely but costs a bit more than the ER70 rod.

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I’m using 80-85 amps. Most of the joints look cooked because of the multiple passes I took. I am getting better on the first pass but need more practice. I was using weldmold 880 to practice at the beginning but decided to switch to ER70S-2 because it is readily available here in Canada. I am saving the weldmold 880 for use on actual frames. I’ll pick up some ER70S-6 and give it a try. I am going to make some 60 degree practice welds, thanks for pointing that out. I have been making 90 degree welds this whole time.

Welding 60 degree mitering is so much harder than 90! Thanks for raising the bar! I would much rather have taken a lesson from a pro but not possible with all the lock downs. I’ll keep self isolating with my family and my torch.

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I switched from er70s-2 to 880 filler rod and noticed the difference immediately. Looking forward to trying the er70s-6. I really appreciate the feedback.

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More practice on .035 to .035 material. I find it easier to weld tubes of the same thickness. When welding .035 to .080 (like seat tube to bottom bracket) I have to be very careful with my torch angle so as to not burn holes through the thinner material. Below is 36x 1.5” .080 tube with .035 tubes welded on four sides.

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More practice.

Starting to feel more confident.
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More practice

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Better

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Still practicing almost daily. Finally started on a bike.

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Thanks to all the pros here that are always willing to help!

Fernando

Looking good Fernando!