I am learning gtaw and I am having problems with fillet welds. I am welding a variety of thicknesses of aluminum between 1/8" and 1/4". I think my problem is torch angle. Some of the posts suggest a 45deg angle and books and other references suggest 70deg from flat, similar to lap welds. I seem to have trouble keeping my notch uniform and once I lose it I tend to let the plates overheat and you know the rest of the story. Any suggestions?
Assumptions: Lincoln 225 squarewave
1/8" tungsten electode, 2% thoriated
1/16" filler rod (that is all we have right now) Thanks.
Try 1/8" Lanthanated or even better yet, Zirconiated. Thoriated are bad for AC as they will degrade and impart tungsten inclusions into the weld.
Your filler rod is a bit small, but if you get it in really fast I suppose it would do.
OK the basics.
1 amp per 0.001" of thickness for aluminum and steel.
This translates to 3/16" = 0.1875" = 187 amps. Now that applies to a flat, butt joint, single pass, full penetration weld.
Inside fillet welds add 1/3 amps
187 x 1/3 = about 62, so add 62 to 187 for 249 amps.
Outside fillet subtract 1/3 (187 - 62 = 125 amps)
3/32" filler would be way better.
Ball your tungsten using DC Electrode Positive. Point the torch straight down at a chunk of copper or a clean piece of thick aluminum. Bring up the amps slowly until a ball forms on the tip, then back off the heat, and allow to cool before switching machine to AC.
This will give you a much better ball than AC. A smoother ball means a smoother arc.
Ask more specific questions and I can give you many many answers, or just go to google groups and do a search for my posts.
do as Ernie says. use "white" tungstens. i grind my AC tungstens on the grinder, just grind the end round.
i find i need to work AL with higher amps than 1 per .001". i run more amps and weld faster. my TIG's AC also allows me to adjust the duty cycle between DCSP and DCRP (ac is dc in sp and rp modes). i tend to favor "rp" because it runs a more narrow focused arc. odd that i say "rp" right ....? this is because my TIG manual says to put the torch on the "+" side of the welder, which is opposite of the DC setup ("+" is the ground clamp when in DC mode). what puzzles me is, why switch where the torch is if AC mode is a balance between DCRP and DCSP ?????
anyways, Ernie certainly knows more than i, but from my experience i'm guessing its not the angle that's causing to the grief, its your setup.
I don't know what machine you have but if it has either square wave capabilities or balance control it can make a lot of difference how you hook up your torch for instance set the balance to full pen. then reverse the conections and you end up with full cleaning Dave
I would find this setup fairly difficult 1/16 filler and 3/16 material with too much forward torch angle (what you are calling 45deg.) and the extra heat of an inside fillet plus trying to feed the filler in from the front of the weld.
first of all the heat from the torch is traveling in front of the weld, which will melt that thin filler before you can get it near the puddle if you try feeding it from the front. feeding in from the side would be slightly easier
second when you lay the torch down that low it can act like a siphon so that instead of having the gas spread out over the weld it can draw air into the weld from behind the torch, (saying that I risk having pipeliners tell me about walking the cup, but that doesn't work on aluminum when the cup is red hot )
clean your material .set up your machine as per Ernies recipe and try a torch angle around 10-15 from vert / *------ Dave