Since someone asked for it, here's my project log of building a TIG welder from the ground up (not from a stick welder). Three transformers provide 20 volts each, at probably 50 amps each. I'm going to need to install a 240 volt outlet if I really want some power, the power factor on the transformers (rewound microwave oven transformers) is pretty bad. So far I've tried the transformers and the HF/HV starter, but not together (need a cap for a low pass filter to prevent HV entering the transformers. Power control is provided by a phase angle control, two anti-parallel SCR's (while essentially a triac, triacs have problems with inductive loads, sometimes they dont turn off at zero crossing). Pictured is a triac, although im going to the surplus store tomorrow for the biggest scr's they have. Tig torch is WP17V, with valve.

Some pictures

MT1 broke off the triac

No pictures on this update, but I did find a very large fan for the triac, and some emi suppression caps for adding HV. Also bought four 70 amp diodes, which will do until i can find some stud mounted ones on ebay. All together, less than $20.

Do you have a wiring schematic for this. I bet I could scrounge up most of this.

Very interesting !

I'd like to see a bead you've layed with it.

I'd like to see a bead you've layed with it.

When I do start welding, I don't think it will be pretty. I've never welded tig or even OA, so don't expect anything great.

Schematics are in pdf and dxf

Wheres the thread on your DIY Plasma Cutter? :)

Some new pictures. Sorry people on dialup (~2mb)

24-The welder on a prototype case. The "case" is pretty much non existant until I get the plasma cutter working (tin snips are painful)

25-The arc starter, only the transformer has been mounted. It's a 9kv/30ma unit, so it probably needs a seperate circuit from the welder (rated 240va)

26-The front plate, incl. circuit breaker and current adjustment pot (which is unconnected)

27-HF suppression caps, to prevent the power stage from being destroyed by the arc starter

28-A large 120 vac fan

29-The starter tank mmc, aren't those caps familiar?

30-Adjustable Spark gap, a 10-32 screw will clamp the electrodes (tungsten) in place

33-Poor man's HV wire, just some clear plastic tubing around a 600v rated wire

34-Heat sink compound

35-Triac next to triggering diac on top of a big heatsink

Does anyone have an suggestions on how to flatten aluminum sheet? It's bent out of shape from the tin snips, and I can't seem to get it flat again.

I am also very interested in your work. It would be nice if you could put some size and values of the components in your pdf file. With the rewound transformers the voltage and wire guage also would help.
Thanks, John

The HF suppression caps are rated .047uf 1600 vdc, 900 vac with 5 parallel sets of two in series, giving a .235 uf 1800 vac bank of capacitors. Secondaries are ~22 volts, using around 20 turns of 16 ga plastic insulated (non magnet wire, much cheaper) wire. The tank cap is around 30 of the same .047uf caps in series.

I'm pretty sure I need a better power control circuit than what I have, so the details on that will come later.

Great work. Its certainly coming together. :)

I finally had a chance to run both the arc starter and welder, and am slightly disappointed. There's two issues:
First, the plastic holding the spark gap pretty much caught on fire. There is a fairly easy fix, move the gap to the exact center, and if necessary, add a fan (would also provide some arc quenching=better performance)
Second, and more importantly, the arc would not sustain full power. Without a capable amp meter, I can only guess the cause. I have a feeling the transformer (I'm running only a single transformer to prevent tripping the house breaker), is saturating. The HV arc would stay on the entire time, but the high current arc would only be sporadic, despite the arc distance. I'm going to run it again tomorrow with the second transformer running off a different branch via an extension cord, and see if I can't get an arc to sustain. But it was definately a welding arc.

Edit:
After some reading, I realized saturating a transformer is impossible by excess secondary current draw (it's dependent on voltage and frequency only (chair)) I guess my next option is the second transformer, maybe in series.

Sorry for the long wait, but there's some good news....

It works!!!!!

The 25 amp circuit breaker (the one on the aluminum front panel) kept tripping, which might be a good thing depending on how you look at it (3kw of power...). It would start an arc at about 1/2" away from the workpiece, which caught me by suprise a few times. I could weld for about 5 seconds before the breaker tripped, which may explain why the puddle just looks like a blob of metal. I also think the shielding gas flow rate was too slow, or the electrode was too far out of the cup.

Tomorrow I might try using two seperate 20 amp outlets with an extension cord, and without the 25 amp breaker.

Now does anyone have some 100+amp diodes? :p

A few more pictures

It seems the filler doesn't really want to stick to the aluminum. Is this caused by surface oxidation? The duty cycle is fairly low, even with a fairly large fan on it. I'm going to see if some secondary side ballasting can help limit current.

I'd really like to see how it compares to a real tig welder. The closest to a bead I could get was the bottom of the first picture. As soon as the puddle develops, the surrounding aluminum starts melting. I'll try again tomorrow. I only tried to lay a bead on aluminum because I don't have big enough diodes for steel.

(The switch on the torch controls a relay which controls the HF starter)

What shield gas are you using and what type of tungstun?

What shield gas are you using and what type of tungstun?

Straight argon and pure tungsten (green). HF was on the entire time, aluminum is unknown extrusion alloy. Filler is 4043.

all that is good but it looks like you could use a little cleaning on the aluminum.

Aluminum to get a good weld must be very clean. And depending on the amperage/voltage used you might have to preheat the metal to get a good weld started.

If youve never welded before aluminum isn't the best thing to start on and definitely not on a rigged up welder.

just my 2cents

The oxidation on the AL can definately be a problem, ANY contamination on AL make it more difficult. Best thing to do is wire brush it just before you weld with a stainless steel brush. (normal steel one will leave residue as well) Even with it very clean, starting a bead is tuff if you have never done it. You will see the surface turn dull, this is the remaining oxide on the surface of the molten puddle. You have to stick the filler rod into the puddle to break this surface. Once that is done the bead will form much easier because the fresh metal is inside the sheld gas area and will not oxidize as fast. Another thing that can cause problems is the fact that AL conducts heat so well that if is laying on a steel table it could be soaking up the heat. It looks like you are useing a very thin piece so this may be to your advantage to keep from mealting the whole thing. Very large peices of AL you need to preheat before welding to get a good joint.
I failed to pay attention to your earlier posts, are you using AC or DC? AL needs AC if you are using argon or argon/helium mix to help "scrub" the oxide away. If you are using DC you can use pure helium I am told. (never tried it myself) Steel needs to be welded using DC with ground on the work peice. 2% thoriated(sp?) "red" tungsten will give you a better weld and last alot longer on steel but will contaminate aluminum.
I hope this info helps, good luck! Keep on posting!

I failed to pay attention to your earlier posts, are you using AC or DC? AL needs AC if you are using argon or argon/helium mix to help "scrub" the oxide away. If you are using DC you can use pure helium I am told. (never tried it myself) Steel needs to be welded using DC with ground on the work peice. 2% thoriated(sp?) "red" tungsten will give you a better weld and last alot longer on steel but will contaminate aluminum.
I hope this info helps, good luck! Keep on posting!

I'm using AC, which is why I tried aluminum. I also tried to tack weld two ~14 ga pieces of aluminum sheet. I noticed it seemed to only heat one at a time, and both failed to stick together. There was a slight gap between the plates, but it wasn't more than 1 mm. I didn't brush the surface, so that might have something to do with it.

I've welded aluminum with my mig welder, but that was an excercise in frustration. I probably should've used a teflon gun liner, but never bought one.

I definately need a better way to cool the transformers. Oil cooling would be an option, except the whole flammability issue.

You definately have to use filler rod with aluminum to break the surface and get them to stick. You cannot "tack" or fuse aluminum together like steel. Once the puddle starts on one piece it will help the heat flow to the other, sort of like tinning a soldering iron. The heat flows with the arc and both will take the path of least resistance. Once the puddle starts you can help control how hot it gets (since it looks like the variable peddle is a bit in the future for you! :) )by adding rod faster or slower.
I am far from a pro at TIG, but fake it pretty good and have been lucky to use good Miller and Lincoln machines (and had good teachers). I feel for you learning on a machine when you are not even sure if is working right. If you get a chance, try out a real machine so you can tell better what is wrong. I'll give what advice I can if you ask.

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.

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

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? :p

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? :p

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

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

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

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

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.

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

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

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.

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

Nice welds Mortek

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

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. :)

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?

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 :D. As to the questions about stick/tig, the older (pre-squarewave) machines are just stick transformers with the HF circuit added to them.

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

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.

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