Advise settings on a 200DX for aluminum?

[Zmechanic]

If you are going to continue to practice with aluminum, you really should get some something other than that narrow flat stock.

It looks like you are building the heat up in the material until it puddles, but since the piece is so thin and narrow, it can't dissipate and it eventually washes out and burns through. This is precisely why pulsing, or using a pulser, comes in so handy close to edges or on thinner material. It stops from building up excess heat in your workpiece. Unfortunately for you, though, all your welds are basically edge (or close to edge) welds, because of how narrow that flat stock is.

Stick with it! You'll get there.

[Rivets]

Here are a couple of shots of my latest progress. I was using the settings given in post #2, with the pedal knob as pictured (I wish there was some kind of divisions marked around the pedal knob, so i could make my best adjustment closely repeatable).

Joe,

I don't have your pedal, but is'nt that knob held on to the shaft with a set screw ?

You could remove it, stick a piece of white cardboard or paper over the shaft, re-install the knob and then mark your own divisions ?

Cheers,
rivets

[zoama]

Joe,

I don't have your pedal, but is'nt that knob held on to the shaft with a set screw ?

You could remove it, stick a piece of white cardboard or paper over the shaft, re-install the knob and then mark your own divisions ?

Cheers,
rivets

Or just use a silver sharpie which is also great for marking steel.

[Joe from NY]

You're way too hot on those welds. Lower your current and focus on a small area at a time, then move on. It is not a race and may take a bit of time to get teh puddle to form.

I believe part of the trouble is that i haven't cleaned the metal enough, and i couldn't get it to start to puddle without stomping on the pedal. Themn when it finally started to puddle, it just flowed away and collapsed.

From the looks of things, you will likely be better off starting with steel, first just pushing a puddle with no joint, then moving to joints. With steel, you will be able to distinctly see the puddle forming, not so much with aluminum and it will melt through as you have been experiencing.

I am OK with steel, i get a good puddle, and can push it along fine. I joined a few pieces of 1/4 inch stock and beat the hell out of the joint in a vise, and it would not break. It is the aluminum that gives me the problems.

If you are going to continue to practice with aluminum, you really should get some something other than that narrow flat stock.

It looks like you are building the heat up in the material until it puddles, but since the piece is so thin and narrow, it can't dissipate and it eventually washes out and burns through. This is precisely why pulsing, or using a pulser, comes in so handy close to edges or on thinner material. It stops from building up excess heat in your workpiece. Unfortunately for you, though, all your welds are basically edge (or close to edge) welds, because of how narrow that flat stock is.

Stick with it! You'll get there.

I have used the pulse, and that is what gave me the best results in the bottom of the middle photo above. I am glad i got a machine with pulse capability, rather than the Miller 165 i was originally looking at. It sure does make a difference. I think when i get some acetone, and get the work very clean, i might have better luck getting a puddle without all the schmutz floating on top. When i kick up the heat to burn it away, it gets out of control, and it gets destroyed.

Thanks to all for your help so far. It gets a bit discouraging, since the steel seems to be so easy, then i grab a piece of aluminum, and it is a totally different story.

[Joe from NY]

After burning up a couple of nozzles, and mashing up the copper consumable parts in the torch (partly due to having the polarity reversed) shut down my practice the other day, i ordered a bunch of consumables from weldingcity on ebay. They have excellent deals and super fast shipping. I feel so ripped off after dropping about $25 last week at my local welding supply for a couple of nozzle cups and collets. I ordered about $60 worth of stuff from welding city so if i mess up my consumables, i can swap in some new ones and keep at it.




My latest practice is getting me further along to get to where I'm improving. I was using a 1/16" 2% Ceriated grey tungsten, gas lens, #4 cup
pulse freq at 1 oclock
pulse amps all the way down to 5
pulse time on at 1 oclock
A/C freq at 11 oclock
A/C balance all the way left to 30% -

[jakeru]

A #4 cup is very small and you might want to consider it primarily a "specialty cup" for when you want to save gas and don't care about oxidizing things (like, if the surface will be ground away after welding is completed, or appearances are unimportant.) I don't think I'd use that for any aluminum welding. To use a #4 cup properly, you will need to make sure you are not running very much argon flow. In fact, something like 8 cfh is about ideal on a #4 cup with a gas lens. (LPM, which your flow gauge may read in, is lower than CFH.) Too much flow for a cup can induce turbulence of atmospheric air into the shielding gas coverag area (and, even a gas lens has a limit.)

I would recommend for aluminum in this size area, a #5 or #6 cup, and about 12 cfh - 15 cfh respectively for those cup sizes. (LPM is about half that.) Keep in mind when you increase cup size, the cross sectional area increases as a square of the diameter. So, a #5 cup has 56% more cross sectional area than a #4 cup, (despite its diameter being "only" 25% larger.) Too much gas flow speed out of a cup can also make the arc erratic (you may notice the arc being harder to start.)

Also, I doubt even after extensive experimentation, you will find any benefit to using pulsing on aluminum, rather than just varying your A/C frequency to narrow the arc cone width when desired. For simplicity, I would turn the pulsing off when welding aluminum. Pulsing (either low or high frequency) can be beneficial for welding steel and particular stainless steels though. But for now I would not use them. Maintaining proper torch angle and arc length are very important. I would focus on those parameters. They are very important for ANY TIG welding regardless of the machine parameters.

When running a weld bead on a small workpiece such as what you've got, limit the "arc on" time to maybe 10-30 or so seconds if possible, and allow resting time in between to allow the workpiece to cool. Otherwise it can overheat, and you will lose control of the puddle. If you see an area sink under what looks like a cellophane "skin" layer on the top, you've got a large area molten underneath the surface, and need to give the workpiece time to cool down. Also, overheating can also often give a "grainey" texture. When the workpiece is more colder (that is, there is bigger temperature difference between the molten puddle and the temperature of the metal that is let's say a half inch away from the puddle), you will need to weld with higher amps to get the same puddle size, but you will have better control over the size, direction, etc of the puddle while doing so. As the rest of the workpiece gets hotter, (perhaps unevenly) the workpiece will begin melting uncontrollably and also oxidizing (because the TIG cup is really designed to keep from oxidizing only the metal that is near the arc.)

[Joe from NY]

thanks for those tips. i will get back down there later after midnight to try it out. i did have issues where the puddle was too wide, thats why i looked to a smaller cup. i thought it would keep the arc narrower. i guess that is not correct. i do notice i need a narrower arc cone to stop getting that wide puddle that i sometimes get. would the AC frequency have any effect on this issue?

[jakeru]

I think the width of puddle problem is caused primarily by overheating such a small work piece. There are ways to narrow the arc (such as cranking up the AC frequency) but really they are just for getting that last 5-10% of the puddle control. You need to get the first 90-95% of the puddle control by getting the manual/fundamental techniques under control first. You can't make up for lack of the "basics" by adjustment of the knobs. The AC Balance knob is a really important basic setting though. I'm not sure what to advise for what AC Frequency setting someone learning should set. Perhaps just put it in the middle, as sort of a general purpose setting. My machine doesn't even allow adjustable AC frequency (it's pre-set at 60Hz.) I have experimented on other machines with AC frequencies as high as 300Hz though. It's just for getting that last 5-10% of the desired weld bead profile, IMO.

I have read that using a smaller cup limits where the arc can go, and I think there is some validity to that. For that reason, it might be beneficial to use a cup in the #5-#6 range, rather than a #8. It may be more important to use the right size tungsten. Too little current on too big a tungsten, combined with a really big cup can really make the arc wander.

Oh, and that last point brings me back to not letting the workpiece overheat. When the workpiece really heats up, you need to compensate by using less current to prevent the puddle from growing uncontrollably large. Then when you compensate for the overly hot workpiece by using too little current (perhaps, by pulling back with your footpedal without even thinking about it) for the tungsten you've got, you can lose directional control of your arc, further contributing to loss of puddle/heat control. Perhaps increasing the frequency can help a modest degree to help maintain directionality of the arc, but I would tend to really try and think about the basics. Really there is not a huge amount that 300Hz buys you over 60Hz. I've heard mark advocate using a footpedal with a torch trigger for learning, and there may be some benefit to that in that it would force the student to wait when a workpiece overheats for it to cool.

I forgot to mention something else important for a beginning to focus on: try to not let the arc get to your filler rod. Maintaining the right torch angle (not angled over too far to the side) is really important for this. You want to melt the workpiece first, and then allow that puddle to melt the filler rod (inserted into the edge of that puddle) to build the puddle up higher. You don't generally want to melt the filler rod directly with the arc. If you drip a melted filler rod onto a solid parent metal surface, that is generally bad technique. If you melt the rod with the arc you can have oxide inclusions and poor penetration under the surface... real bad stuff for weld quality on aluminum. You can get aluminum oxides to float up to the top too, but only after making a huge puddle and only when the oxide layer isn't too thick. Using proper current and recognizing the puddle in the workpiece is something to learn, and *only then* introduce the filler rod into the puddle. It's challenging, because there is a short time window where you need to add the filler rod, to keep the puddle from growing too large. But with time, you'll be able to recognize the puddle, time your filler rod additions and you'll achieve a consistent weld bead, with very strong and sound qualities (no oxide inclusions "underneath the surface".)

If you are not sure if the workpiece is clean enough to weld, try lighting a very light / low current arc (preferably low enough current so as to not melt the surface at all) over the surface where you plan to weld. If the resulting aluminum surface after being etched with the low current AC arc is completely "white to grey" in its color, (and is not "brown" or "smokey" looking), it's clean. This can be useful as a quick and easy "check for cleanliness" before welding any aluminum that you are not sure if it has things on it like oil or water (hydrocarbons, which can cause porosity in your aluminum puddle.)

I hope that is not too much to think about, try and just vary one thing at a time. There may be some value to not even adding filler rod at the very beginning. Just try and carry a uniformly sized puddle across the surface of a workpiece. Only after you can recognize the puddle immediately when it appears (it will look bright and shiney by the way when there are no oxidation on the top of it), work on introducing the filler rod.

[performance]

thanks for those tips. i will get back down there later after midnight to try it out. i did have issues where the puddle was too wide, thats why i looked to a smaller cup. i thought it would keep the arc narrower. i guess that is not correct. i do notice i need a narrower arc cone to stop getting that wide puddle that i sometimes get. would the AC frequency have any effect on this issue?

AC frequency will definitely have an effect on puddle width and arc width, but so will speed. You may be waiting too long.

I am wondering if it is possible that you are having a problem with puddle recognition. The aluminum puddle doesn't really change colors, and it is just a hint of shine that signals that the puddle is ready to add filler. I remember that was the hardest part for me.

[sportbike]

Try making a cold, bird poop looking weld.
Then go somewhere in between bird poop and where you are now :-)

[Jake98]

Great info. Thanks to all.

[performance]

Try making a cold, bird poop looking weld.
Then go somewhere in between bird poop and where you are now :-)

Excellent advice.
I was thinking about that myself...A little too cold of a weld with aluminum while learning is easier to manage than too hot of a weld...

[Joe from NY]

Thanks again for the advice, gentlemen. Here are my latest efforts. These show several passes laid on top of each other. The advice on turning off the pulse was right on. After I did that, my puddle appeared faster and was easier to control. Part of my problem was hanging around in one place too long waiting for a nice puddle to develop. Sometimes, before the puddle would appear, the surface looked like a bunch of ground up fish scales appearing out of the metal and dancing around in the arc cone. Also, I am also using my new Jackson WF60 Truesight helmet, and I am not getting flashed anymore. That is a big help. I started with a 1/16 cerciated tungsten but wound up doing the later passes with 3/32 Red tungsten with a gas lens and a #6 cup, about 8 LPM flow. One earlier issue was i only had 1/16 rods, so i twisted them double like Twizler candy and then the beads looked a bit better.




I am calling it quits for the night, and will get back on it Tuesday afternoon. Thanks again to all for the encouragement.

[sportbike]

Now you are starting to get somewhere. Were those welds "as welded" or did you hit them with scotch brite after welding? If they are as welded, you may still be a little on the hot side (note the weld beads look a little sort of "hazy" or textured).

[Joe from NY]

after i laid down the first few, i hit them with the stainless brush before i did the last shiny ones on the top. they have a different appearance in the photo.

[Joe from NY]

I didn't make it to the supply store to get any rods today, so I will likely not report any progress tonight.