I'm also a hobbyist trying to learn more, so I may get a few of the terms wrong.
I am trying weld 1/8" aluminum angle (2.5" legs) to a 36"x18" 1/8" sheet. This is a project for my brother and the sheet/legs are being turned into shelves that slide on heavy duty drawer slides. I am using a Lincoln Square wave 200.
I have the balance set to 70, and I have tried between 60 and 130 hz on frequency. I am using 3/32 2% lanthinated tungsten and a 3/32 5356 rod. Initially, I was using a #7 gas lens with about 12 cfH 100% argon. I am cleaning the plate and angle with a wire brush on an angle grinder, then a dedicated Aluminum SS wire brush by hand, and then wiping everything down with acetone, including the filler rod.
My issue is on the backside of the angle. I believe this is called a T joint. The heat is getting pulled away both by the sheet and both legs of the angle here, especially along the bottom where the sheet and angle are doubled up.
I've run up to 190 amps on this joint. I can feed the rod into the root some of the time, but mostly it wants to bridge and melt the filler away too quickly, and I don't get the rod into the puddle. I also cannot move very quickly or I lose the puddle on the angle side of the joint, and anything below about 180 amps won't really puddle the angle.
I have also tried a torch angle nearly parallel to the plate, so its pointed almost directly at the angle. Again, no dice.
So, the high amps combined with the slow travel has two issues. The biggest is that it is heating the part up so much that its warping into all kinds of shapes. The second, which is a machine annoyance of mine, is that the 200 square wave has preset postflow and at 190 amps, it just keeps flowing and flowing and I'm burning through Argon like crazy.
So, I was watching some of Jody's videos, and saw that he often uses a little bit of helium mixed in, from about 1/8" on up.
PERFECT! I thought, I'll go grab a small tank and give it a go (I was excited until I saw the bill for a size 20 He tank,
).I rigged it up with a janky "T" and an old Smith flow gauge from my old Miller 175. I know that the flow of Helium is going to be higher than indicated on an Argon flow meter, so I was just opening it enough to get the needle to just come off the pin. I set the Argon to around 10 cfh. I also switched to a #5 cup and had about 1/4" stickout, which is enough for me to see the arc clearly. Away I welded.
Below are two welds one with 100% argon, one with my crude helium mix. I know they are far, far from perfect and wouldn't pass anyone's test, but they are not structural, and are not in a position to do any damage if for some reason they fail, either to property or to people. It seemed like a good practice project.
Both welds are with the same cup but the argon is at 190 amps, 100 hz, and the mix is at 130 amps, 120 hz. The helium mix welded much quicker, and I was able to easily get rod into the root. However, it was popping and banging like crazy, and left a gray "ash" coating on the surrounding area and the weld. In the picture, you will see that I cleaned it off, which I realized after the fact that I should have snapped a picture first, but I wanted to see the weld appearance without the gray coating. It easily came off with a hand held wire brush.
The snapping and popping arc, from watching Jody and JD, and others, suggest gas flow (too high) is likely the problem. However, I wasn't sure if the gas flow would cause the gray "ash" to coat everything. In one of WTAT podcasts about aluminum welding, Jody mentioned getting balloon gas instead of weld gas. I am a little suspicious of my supplier since the guy helping me tried to sell me a premix of argon, co2 and a small amount of helium though he knew I was TIG welding Aluminum. Maybe its a thing, but I've not come across that.
Anyway, I don't want to go spending a bunch on new flow meters and valving and such if its a gas quality issue, so I thought I'd ask here first before doing anything else. And, any other advice is always appreciated. Thank you for taking the time to read this and for your help.
Isaac
- Helium mix weld, ash cleaned off
- IMG_4959.jpg (50.71 KiB) Viewed 498 times
- 100% argon weld, bridged over the root
- IMG_4960.jpg (51.94 KiB) Viewed 498 times
