Multipass T-Joints with 14 gauge carbon steel

MichiganWeld15 · Thu Oct 23, 2014 5:13 pm

I'm new to welding month ago I started TIG welding and I am currently am taking 2 classes for it in my night class we are using 14 gauge Carbon Steel and I have my lap, outside corners, and T joints down to where I'm satisfied in Horizontal and Flat postitions. My instructor wanted us to try Multi Pass T-Joints and I seem to be laying the initial bead and bottom bead with ease but when I try and lay my top bead I screw it all up thus starting all over, does anyone have any tips on how I could fix this? Also what can I do to improve overall welding on thinner metals such as 16 or 18 gauge steel?

Mongol · Thu Oct 23, 2014 8:52 pm

Define "screw it all up."

And on thinner stuff, I like to get it relatively hot and move fast.

Mike · Fri Oct 24, 2014 9:12 am

Welcome to the forum.

rick9345 · Fri Oct 24, 2014 10:07 am

a picture
torch set up
machine settings
welcome to forum
help will be here

Superiorwelding · Fri Oct 24, 2014 5:27 pm

My guess off hand would be you are not letting your coupon cool or not turning down your amperage for the third pass and burning through the back side. Or, being to hot, your weld profile severely flattens out. Correct?
-Jonathan

AKweldshop · Fri Oct 24, 2014 9:04 pm

You really think you need multiple passes on 14ga????

MichiganWeld15 · Mon Oct 27, 2014 8:37 am

AKweldshop wrote:You really think you need multiple passes on 14ga????

no but if you read what I said it's because I just started learning TIG and I'm in a class welding for a grade.....

Tue Oct 28, 2014 7:08 pm

MichiganWeld15 wrote:I'm new to welding month ago I started TIG welding and I am currently am taking 2 classes for it in my night class we are using 14 gauge Carbon Steel and I have my lap, outside corners, and T joints down to where I'm satisfied in Horizontal and Flat postitions. My instructor wanted us to try Multi Pass T-Joints and I seem to be laying the initial bead and bottom bead with ease but when I try and lay my top bead I screw it all up thus starting all over, does anyone have any tips on how I could fix this? Also what can I do to improve overall welding on thinner metals such as 16 or 18 gauge steel?

What you're describing sounds like a 2F position, a Tee- or inside coner-joint with one leg flat on the table and the other leg vertical. I'm going to guess you're getting serious undercut on the third pass. The previous comments about not allowing the coupon to cool and/or not backing down the current make sense here. Realistically, on a job, you will only have time to force-cool the weld, preferably with compressed air, and your machine may be some distance from you, making adjustments impractical. I humbly suggest the following... drop your current setting about 5% (and take the little bit of extra time in the first pass... you'll make up for it in the end result), cool between passes as much as you can, and on that third pass that's being a bear, change your torch angle to almost parallel to the bottom plate and straight in 90* to the vertical face, so the arc-force pushes your filler up and back, and get off of the top edge quickly after the metal melts in.

No two of us do it exactly like, so you'll have to experiment with the suggestions you get to see what works for you; Like a MIG chart, it's a starting point only.

And if I've misunderstood the problem, please clarify it so I can offer more appropriate suggestions.

Steve S

TamJeff · Wed Oct 29, 2014 12:59 am

Make the bottom pass the last one.