[Corvus corax]

You will probably find it relatively impossible to weld aluminum. Even with a proper TIG setup it requires a fair amount of time to get the technique down, and consistency even longer. I would concentrate next if I were you on making the welder operate on DC. AC welding with TIG works well once you are able to unbalance the waveform to the negative side, as the balanced waveform you currently have will overheat the tungsten in short order. Positive polarity with respect to the workpiece sends about 80% of the heat to the tungsten due to ionic bombardment. In any given arc, the anode always gets hotter. Welding steel is a doddle compared to welding aluminum- about half the heat input required, because steel is a very poor conductor of heat away from the weld pool. You can weld it fine with an AC waveform as well, but AC waveforms are difficult to control unless you have fast zero crossing electronics built in to your welder. The arc typically extinquishes during the zero crossing event, unless your using SCRs and two seperate DC supplies, to speed up the switching time. Otherwise, you will be using HF the whole time to keep the channel open. With DC, you don't even have to use HF start, simply lift or scratch start the arc.

Also, thoriated tungsten is fine for aluminum- I've used it for years for that purpose, and stopped using pure tungsten long ago. You'll find 2% is far more durable for a given tungsten diameter, and arc starts are superior. Lanthanated is better for aluminum, but it is harder to find here in the states. And if you haven't already, get yourself an ARC welding helmet, or you'll find that "sandy" feeling in your eyes getting worse. If you haven't experienced the delights of arc flash in your eyes, or on your skin, I'd be surprised. That goes for plasma cutting too, especially on aluminum. It takes about fifteen or twenty seconds of arc time using my welder at 200A on aluminum to induce a burn on any exposed skin similar to what one would get after a full hour in the Florida sun. Wear a long sleeved shirt. Medium wave, short wave, and vacuum ultraviolet is produced in PRODIGIOUS amounts by these machines. The acrid smell while working a TIG isn't from the arc, its from the UV light produced, powerful enough to rip the oxygen molecules in the air apart, producing monatomic oxygen, ozone, and nitric acid.

[motomitch1]

surface oxidation needs to be cleaned off before you try to lay a bead.

it takes less amperage to tig weld steel so you could use smaller diodes for steel

[js530]

And if you haven't already, get yourself an ARC welding helmet, or you'll find that "sandy" feeling in your eyes getting worse.

I've been using a helmet (for mig), just the whole arc-starting-away-from-the-workpiece thing has caught me by suprise a few times.

The acrid smell while working a TIG isn't from the arc, its from the UV light produced, powerful enough to rip the oxygen molecules in the air apart, producing monatomic oxygen, ozone, and nitric acid.

And, in my case, the spark gap. Running for just five seconds with the garage door shut produces a noticable smell.

Some conclusions...

I've been experimenting with the "welder" for a few hours, and it's just not very practical. Two MOT's have died (I believe heat related causes), and about the only thing I can weld with one mot is some 16 ga steel. The starter works perfectly, maybe even too good (or is it "too well"...?). Is it normal for an arc starter to allow arcing ~3/4" away from the workpiece?

So yes, it is possible to build your own TIG welder, but it's much easier/reliable/useful to find a used stick welder, and add a torch and starter. Which is exactly what I'm going to do next. Now does anyone have an old stick welder in the DFW area?

[dumaster]

So yes, it is possible to build your own TIG welder, but it's much easier/reliable/useful to find a used stick welder, and add a torch and starter. Which is exactly what I'm going to do next. Now does anyone have an old stick welder in the DFW area?

hello js530

I found this project very interesting, I have a stick welder , it wanted to
know if I to rectify it, and to make the high-voltage circuit, I will be able
to use it as a TIG ?

Another one doubts is if the high-voltage can be used to stick welder,
and as it is the construction of the Coupling Transformer, it would
like to construct one!

I wait a return !!

Best Regards

Eduardo

[dumaster]

it has some friend to help me here in the questions above ? ^^^^^^^

[Ed VanEss]

alum is fussy,must be very clean -clean with stainless brush. concintrate your heat on the part. When it starts to look wet, add wire. always keep the wire in the shielding gas,[near the cup]- use argon gas @ 20psi. tungston-use .093zirconium or pure. try 4043.o62 wire. Lot of welders use to big of wire, which is fine on heavier parts. Tungston should only stick out of cup the di. of the tungston, unless using a gas lens. must be set on ac with continuos HF. you might be better off practicing on steel. its a lot easier for starting out. for steel, use 2% thirated tungston.093 di. sharpen to a clean point. dc current 15psi argon .HF only for starting. should also have a post flow on the shielding gas to keep the tungston clean as it cools, [about 3-5 seconds]
Practice-Practice-Practice

[crease-guard]

All of the above advice is spot on and is worth a semester in welding class just reading.

I have a ThermalArc 185 unit in my garage I use for welding aluminum and what not. My welding prof told me that in order to get a good weld (in addition to all the things mentioned previously) you needed to put a lot of heat into the initial arc to create a puddle as quickly as possible, then add the filler in as mentioned before and start moving. As you start to create a longer bead...you're heating up the aluminum even faster and the puddle will start to widen because you now have too much heat in the puddle. You need to use your foot amptrol to back off on the current or you will burn through the alumium. You'll also start to warp longer pieces if you run beads too long, so you need to tack at multiple spots and run shorter beads to keep the metal from warping.

Aluminum is a bugger to weld. More an art than a science. but even for me, I've gotten OK with my aluminum welding.

Jay

[Ed VanEss]

when welding alum , do NOT mash the pedal to heat the base metal quickly. to much amperage will cause the tungston to spit particles into the puddle. Let the base metal heat slower, and you will have less problems. I had one of the first Miller tig welders around. No foot pedal, and had to crank the amperage to your preferance. That was over 30 years ago.

[ozzie34231]

Hi All,
Would someone spell out what has to be done to a stick welder to get to TIG. Will I spend more than buying a TIG. Since I bought a small Mig unit I haven't used mine. I've welded a lot of metals with the Mig but it just doesn't seem hot enough for Aluminum; wire just sticks, and the wire feed of aluminum is a nightmare. I'm retired so I have plenty of time, I think ;-)
Thanks,
Jerry

[Ed VanEss]

Years ago Sears made a high freq attachment for a stick welder, which I tryed. Took it back and bought a miller. The problem with a stick welder is it must be both AC-DC. There's quite a few used tig welders out there now days. so be better off looking around, or check with a dealer. The problem with a mig for alum is the wire bends pretty easy, pushing the wire through a 12 or 15 foot cable, so a spool gun is the way to go there, but if you want to weld up some neat looking alum projects, you can't beat TIG.
A stick welder is obsolete these days, if you really need stick, you can do it with your tig. look around for a used Miller 250 Dial arc. I,ve had one for 20 years, and as far as I'm concerned, it's bulletproof.
Hope I was of some help.
Ed V

[diarmaid]

Hi All,
Would someone spell out what has to be done to a stick welder to get to TIG. Will I spend more than buying a TIG. Since I bought a small Mig unit I haven't used mine. I've welded a lot of metals with the Mig but it just doesn't seem hot enough for Aluminum; wire just sticks, and the wire feed of aluminum is a nightmare. I'm retired so I have plenty of time, I think ;-)
Thanks,
Jerry

How 'small' exactly is your Mig ?

From my limited knowledge, a spool gun is a good idea, perhaps essential. If you want more heat with your Mig crank up the volts and reduce the wire speed.

[Mortek]

Here's a sample of a project I am "currently" welding. Done with a Miller Syncrowave 350 LX
2" diameter 6061 aluminum tube 1/4" thick. About 250 amps 3/32" 4043 rod

[diarmaid]

Nice welds Mortek

[ninefinger]

Hi All,
Would someone spell out what has to be done to a stick welder to get to TIG. Will I spend more than buying a TIG. Since I bought a small Mig unit I haven't used mine.

If you're electronically inclined I found a guy who did make his own TIG, and he did it right - variable everything. His design requires only a low voltage high amperage power source (like those "obsolete" AC stick welders).

I've started thinking about his design and have started to make a parts list for Digi key - so far I'm at ~ $160 for parts - probably need another $60 or so by the time I get all the little things added on.

Add a Stick welder for ~ $250 and a ton of shop time (...which I don't have)

http://www3.telus.net/public/a5a26316/TIG_Welder.html

Mike

[diarmaid]

Wow! Thats such a great link. Thanks ninefinger.

Wish there were more comprehensive instructions though, as I dont have the knowledge to make something just from his electronic diagrams. Definately an experiment/project for the future.

[s_c_engineering]

your welder would work a lot better if you put the magnetic shunts back into your transformers, that would get tid of the overheating/frying the mot problems, you should also be using around 10awg wire in those transformers. what size microwaves were those transformers out of?

[tadream]

your welder would work a lot better if you put the magnetic shunts back into your transformers, that would get tid of the overheating/frying the mot problems, you should also be using around 10awg wire in those transformers. what size microwaves were those transformers out of?

That was something that I wondered about myself. I don't know much about microwave transformers, but I was wondering what kind of a volt-amp curve they have. You need a fairly high open-circuit voltage, but it needs to 'droop' pretty sharply while providing plenty of current. This is the difference between stick/tig and Mig power sources. Mig is Constant Voltage, stick & Tig are constant current. All this means is that the mig transformer is more closely coupled than the tig. It tries to maintain it's output voltage while allowing the current to vary considerably to do so. Tig is the opposite. It tries to maintain it's amperage, while letting the voltage vary widely to do so. Part of your description kinda sounded like the transformers might have too much of a 'CV' behavior. Also, yes, your Alum was much too dirty to achieve a good weld, and aluminum tig takes a good bit of practice to learn. Once you have a puddle going you have to MOVE with it, or your puddle will quickly end up in the floor . As to the questions about stick/tig, the older (pre-squarewave) machines are just stick transformers with the HF circuit added to them.

[D_ego]

Hello I made a table to weld (GTAW) to drive a high frequency equipment. the equipment works well but when the arch is created the engines don't work, i want to know why. I am working with a kit xylotex of 3 axes.

forgive my english

[venomx999]

what a crazy creation! if it cost less then its feasible to play with this project...but from what I heard it cost more than an actual machine..lol
Maybe its great for someone who has tons of cash to waste. Until someone comes up with simplier machine where the parts can be found in electronic dumpsters, it is looking like a government funded project lol.

[venomx999]

I was referring to the link on this post to another project ..not this one. Srry for the confusion lol