[piniongear]

Hey there all,
Several weeks ago I posted for the first time on this forum and was (and still am) having trouble getting a good looking bead, and just joining two pieces of aluminum together.
My equipment:
Dynasty 200DX
Argon gas
#20 torch and Coolmate 3 cooler
3/32 Lanthanated Tungsten using 3/32 5056 filler rod

My problem:
Getting a continuous bead on a lap joint.
Material is new 1/8 inch 6061 aluminum engine plate and 1 x 1 x 1/8 aluminum angle.
Several weeks ago I could not get the aluminum pieces to join together no matter what I tried.
All it did was ball up and either fail to penetrate or else it burned through.

For the past week of really serious effort I can finally get the puddle to form and lay a pretty decent bead.
The problem I am having is controlling the bead.
I will weld along for about 6 inches and then start to lose control of the puddle.
It gets larger and larger and the filler rod starts to drop off long before i can stick the end in the puddle. It gets that hot.
To save it, I am backing off the peddle completely and then starting over again.

Here is how I am welding at the moment.....
I have the Dynasty amp set at 125 using A/C setting with the balance set at 80%
I first start the weld with half peddle down until I see the cleaning action start to take place.
Then I press the peddle down full and begin dabbing the filler rod into the lead edge of the puddle about once per second.
The 'cleaning area' is about 3/16 outside of the bead edge.

Everything goes along fine for several inches and then the puddle starts to enlarge and I soon lose control.
What am I failing to do here? Is the aluminum heating up so much I need to either back off the peddle or move much faster?
By the burns on my hands I can tell the aluminum becomes very hot. Ha-ha! I have had to lay a piece of asbestos cloth under my hand to keep it from getting scorched.
And yes, I am using a Tig Finger too.

I realize I should perhaps post a pic of the welds but until then can anyone offer me some help with this?
At least my welding is 150% better today than a few weeks ago, but I still have a long way to go.
Thank you!

[dsmabe]

Lap joints on aluminum can be a pita for me too, but the part about the filler rod makes me think you have too much torch angle. As for the puddle getting away, that makes me think you may have 2 problems. Too long arc length, and your centered up on the joint. The bottom piece takes a lot more heat to melt, so focus more heat on it.
Going back to your arc length, stay very tight, then lengthen the arc when you dab filler to keep from dipping the tungsten.

[79jasper]

I haven't done any aluminum yet.
But from what think, dsmabe pretty much hit it right on. Especially the torch angle part.
A pic is worth a thousand words.

Sent from my SM-T537R4 using Tapatalk

[piniongear]

Thanks for the suggestion regarding torch angle guys.
That may well be one of the problems.

I seem to start off OK, but when the puddle gets larger I lose track of where the electrode is actually pointed at.
This is most likely resulting (or a result of I should say) of the torch angle sloping back far more than the suggested 10 to 15 °.

I will give it another go and concentrate on torch angle and putting more heat on the bottom piece.
I also use a piece of half inch aluminum clamped beneath the bottom piece, so that is going to be a real heat sink I guess and will of course cool that bottom piece a bit.
pg

[Bill Beauregard]

I would try the heat sink on the top piece. It's the smaller mass that benefits the most from a heat sink. I have copper in various shapes (buss bars) It sounds like time to regroup. Watch Some Jody videos. Get a couple of TIG fingers. You need to stay close, between 1 and 2 times diameter of tungsten. Grind tungsten blunt, taper begins 1 diameter back. Either move fast or back off the heat. I would use 1/8" 4943 filler. With practice you'll move fast, minimizing HAZ. I focus the torch between the pieces, near 90 degrees to the weld tilt up or down to balance heat. I believe at your level of expertise you can hold filler an inch away from the torch, or bring it in from the side where it doesn't take on torch heat so much. Never melt filler with the torch. the filler must be melted with the heat in the puddle.

[piniongear]

Thanks Bill.
I will try what you suggest. The piece I am welding on is a 5" x 10" x 1/4" plate on the bottom and the top piece is a 1" x1" x 1/8" angle.
Below the bottom piece I have a 4 x 5 inch piece of aluminum plate clamped in a vise.
The weldment pieces are clamped to this plate which provides me with a flat area to rest my hands.
This plate acts as a heat sink (but that was not my intention) as it turns out.

[whm_fab]

jody does a great video showing the process of lifting the torch slighly as you dab, other than that, as the guys said: arc length too long, and torch angle. you've got to bear in mind that aluminium is far easier to weld when hot, so if your on a foot pedal, you really should be backing off the amperage as you travel and as the work piece heats up. eg if your starting at 90a, at the end of a 300mm piece i would normally be down close to 75 for the same penetration and bead.

[piniongear]

jody does a great video showing the process of lifting the torch slighly as you dab, other than that, as the guys said: arc length too long, and torch angle. you've got to bear in mind that aluminium is far easier to weld when hot, so if your on a foot pedal, you really should be backing off the amperage as you travel and as the work piece heats up. eg if your starting at 90a, at the end of a 300mm piece i would normally be down close to 75 for the same penetration and bead.

What you say makes a lot of sense.
I know the aluminum gets really hot when I have traveled 6 inches.
Thanks for your suggestion about starting at 90 amp (as an example) and closing at 75 amp (again, as an example).
I will try that.
I am trying to keep the tungsten close to the puddle without sticking it as the aluminum is getting hotter and hotter and at the same time keep my fill rod dabbing consistent. When the puddle starts to get away from me I know the angle of the torch is not correct..... I reduce the foot pedal, usually to the point that the puddle goes cold.
I will continue to practice.
If I can better myself with aluminum then I would hope my Tig with steel will improve too.
Thanks again!
pg

[AKmud]

Sounds to me like you are simply going too slow. When you start your bead, hit it pretty hard right off the bat to get the puddle established, then back off a bit when you start laying your bead. If the puddle is slow to develop at first, turn up the amps. I run my Dynasty wide open for aluminum and just use the pedal to fine tune it while welding. With 1/8" material, you will definitely have to keep moving. Right now your issue is overheating the base material (probably going to slow) and your puddle is growing too large. At that point, the only cure is to let it cool down.

Don't forget your pulse capability on the Dynasty. It shouldn't be necessary for 1/8", but it will buy you a little time.

[dirtmidget33]

First off before you keep trying to muddle threw this using bells and whistles pulse, heat sinks, etc to control puddle step back a few notches. Forget about building or working on a project. Get a scrap piece of aluminum and pad beads. yeah it sounds boring , but sounds like you need to learn puddle control, foot pedal control, torch angle control. If you slow down and learn the basics of laying good beads controlling heat, speed of travel, torch angle all these major problems your having will vanish and things will all of a sudden start to work. Those major problems will seem like small potatoes. Forget about those advanced features of machine they have a place but learn to do it without them. All the time you waste trying to find a cover up with features could be well spent learning control.

Jody has a good aluminum video best advice I ever seen. If you do this drill will help out on all materials steel, aluminum, magnesium , stainless etc.

http://www.youtube.com/watch?v=vWNZioJ_FOc

I like doing this once in awhile for the heck of It. That and aluminum cans always have that kind of scrape laying right in kitchen teaches patience and amp control. Might just pad some beads this weekend and weld some cans.

[Bill Beauregard]

Dipping rod in the puddle is equivalent to an ice cube in boiling water. The energy needed to melt filler sucks heat out of the puddle. If you don't back off heat, you drive a 1967 Volkswagen, as it heats up, you have to accelerate the whole process, speed up, move faster. After dipping rod advance the arc to just touch the leading edge of the puddle, As it forms a horseshoe shape around the arc just as the center of the puddle wets and expands a tiny bit, move back a bit with the torch and quickly dip with filler. Speeding up is a good thing, it limits the time heat can spread out to the whole piece. I was having trouble with filler balling up, Dave suggested jumping up a size in filler.
Zap says he sometimes comes in from the side with filler or even from behind. He doesn't see it as being so important to keep the filler in the gas cloud. I move away from intense heat, staying in the gas.
Like a carved turn on skis, or I guess a hole in one for a golfer, making a flawless aluminum weld feels great! That won't happen early in the learning process. It takes a while. I do it sometimes, not always. Steel is more consistent, not as fussy. Stick with it, it'll come.