Welding Tips and Tricks

So I've been practicing on my aluminum technique and have a few questions.

I'm using a AHP 200x set at approx. 130A max, stock foot pedal, 170 Hz AC, 35% cleaning, 3/32" 2% Lanth. tungsten, 1/16" 4046 rod.
Freshly cleaned 1/8" thick Aluminum plate

1) ending
When I am running a bead i try to taper off at the end but always seem to end with a dimple in my puddle. I know that's not a good thing. it seems as I am tapering off the arc just stops abruptly, not the slow shrinking arc that I see on videos. If I taper too slowly I end up overheating the spot and end up with a large dimpled spot. If I taper too quickly I end up with a smaller dimpled spot. I just can't seem to get a non-dimpled spot at the end. Should I be lifting the torch as I taper on the pedal and circle the torch?

2) sq. tubing technique
I am also practicing on 1.25" sq tubing. very sharp corners unlike the rounded corners of steel sq. tubing. I cut a section of tubing and then weld the two pieces back together.(no pics at this time) I find if I start my bead on the corner I get a very rounded corner and sometimes a dip. Am I expecting too much trying to maintain the square edges? Or should I start my bead on the middle of the wall and travel towards the corner? Stop at the corner? Or should I try to continue around the corner and end in the middle of the next flat? lots of questions just trying to figure out a technique for dealing with square tubing.

thanks.

steve

WIth alum I try to taper off but right at the end feed a little extra filler, it takes a little practice alum is the hardest IMO. I can honestly count on one hand how much I have ever used 1/16" alum filler, typically you are using something thicker or it can be tricky to keep up with the puddle, an increase to 3/32" may give you better control of the puddle.

You will not keep the sharp square edge, if you require those that will come with some post weld finishing. With alum the bead profile will not allow it, very normal. I always prefer and recommend, starting before the corner, weld through the corner or wrap the corner and stop in the flat. Do the same and join the beads or restart the bead and continue to through the next corner.

Of course pics always help...

There are far better welders (far, FAR better!) than me on this forum but I'll try to answer your second question, in part, through my own experience.

The aluminium tubing I use also has very sharp corners. I tried tacking on the flat, also tried it on the corners. I settled on putting tacks right in the middle of the flats on opposing sides. I then light up, get moving and roll over the corners. For me, at least, if I roll through the corners mid way through welding a bead, I get a more uniform look. I don't have the out-of- position skills yet complete the whole 360 degree weld in one run. I tend to do it in two runs, stopping each time mid way along the flat before re-positioning to start up again and finish the weld.

I think you are expecting a lot trying to retain sharp corners. I just go for a uniform bead all the way around, on both flats and corners.

Hope this has been some help.


Kym

Thanks for the responses.

In regards to the keeping sharp corners, it was more of a question of what should be my goal (what's the absolute best appearance I could expect to ever attain). First goal is to have a structurally sound weld. Second is an aesthetically pleasing weld, if possible. The idea of starting in the middle of a face and going around the corner hadn't occurred to me until I decided to ask the question. That's what I will practice next.

Rick_H, I will play around with adding filler as I'm tapering. I have some 3/32" filler but I question it's viability. When I first got my machine I went to the LWS and bought 10 lbs ER70S2 and asked about aluminum filler. They disappeared for a while and came back with a handful of aluminum filler, no markings, nothing, dull in appearance, presumably 4046. They said they had had it for a while and just gave it to me. I struggled with my aluminum early on and put it aside until my basic steel technique improved. Once I started my aluminum practice again I really worked on cleanliness and prep. I even scotchbrite'd and acetoned my filler and found I would usually get a better bead. I ordered online some 1/16" since I was planning on using thinner aluminum. It came nice and shiny whereas my old 3/32 was dull. I think my 3/32 is old and covered in an oxide layer which did not help my learning at all.

I realize it's all about seat time, but picking up tidbits of knowledge along the way should speed up the journey.

Once again, thanks for the input.
steve