Homemade TIG Welder

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Homemade TIG Welder

Postby Capt Ahab » Tue Mar 30, 2004 6:19 am

Here is a basic schematic for my homemade TIG welder. It's really this simple. I have been amazed at how well it works. I can make much better welds with it than with my MIG welder that I bought.

For the electric motor I used a 1 hp motor from an old table saw. It works ok for welding small stuff but will stall if I turn the current up too much. The alternator I bought new for $30 from an alternator repair shop. It is a 90 amp Chrysler unit. I've heard that Chryslers are usually externally regulated which means that they do not have a built in voltage regulator. You don't want a built in voltage regulator since you want to manually control the voltage to the field in order to adjust the output to the torch. I used a regular battery charger from Wal-Mart for the field coil power supply. It has a 6V setting as well as a 12V/2 amp and 12V/6 amp settings. For most of the work I've been doing with thin stainless I use the 6V setting. For thicker (1/8" is as thick as I've tried) I use the higher settings. When I first built this welder I used a stainless steel wire wrapped around a board for my variable resistor. I called it my Wire Wrapped Around a Board Current Regulating Device or W.A.B.C.R.D. (pronounced wabcrud) for short. It worked great but it was a bit of a pain to adjust while welding. I've since developed a more sophisticated WABCRD that includes a homemade foot pedal control. I'm still perfecting this but so far it works great. I'm in the process of obtaining components to build a high frequency unit like Al Belli's. I also have ideas for building an electronic device to re-invert the alternator output for AC.
Attachments
Welder Schematic.jpg
Basic TIG welder schematic
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weld.jpg
Weld made with homemade TIG
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welder.jpg
My early setup
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Pedal.jpg
Foot pedal control
Pedal.jpg (27.61 KiB) Viewed 23030 times
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Postby Mike Everman » Tue Mar 30, 2004 7:41 am

Quite ingenious, Cap'n.
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Postby paul skinner » Wed Mar 31, 2004 7:31 pm

Very nice. Necessity, the mother of invention (cliche but on the money).

Didn't Kenneth have a set of plans for building a mig welder on the old site?

Google'd, and there it was...

http://home8.inet.tele.dk/jan_p/welder/mig1.htm

Along with lots of other "Homemade welders"...ok. I've been living in a cave for to long now.

Last edit...

A discussion at a custom car group, about this very setup. Should answer any questions anyone has about how it's made, and how it works...

http://www.turbomustangs.com/forums/sho ... genumber=1
Last edited by paul skinner on Wed Mar 31, 2004 8:31 pm, edited 1 time in total.
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Postby Capt Ahab » Wed Mar 31, 2004 8:30 pm

The Turbo Mustang forum is where I got the idea. My setup is a bit simpler with the Chrysler alternator (fewer wires to deal with). Mine also works well with only a 1hp motor as long as you are welding thin stuff like pulsejet engine bodies.
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Postby sparks » Thu Apr 01, 2004 12:32 am

I was just thinking.... OBIT´s (oilburnerignitiontransformers) must be just right for the HV/HF, i have some that i use for all sorts of HV powersupplies (N2 lasers and teslacoils mostly) and they all seem to fall in the 9-13kV 15-25mA.
This is something i have tried to read up on for some time now but i was more into making some kind of low-power carbon arc style torch with HV/HF and an old AC stickwelder as powersource.
Soldering copper was my intent but mostly playing with different ways of avoiding oxidation and only use equippment made from old junk.

"Re-inverting" the DC... i dont get it.
Theres perfectly fine 3-phase AC available from the alternator, unless you were thinking of trying higher freq. AC.

Btw, on the HV/HF its only the ionizing effect we want, why use a "high power" device like neonsign xfmrs or OBIT´s?
Wouldnt a smaller TV-flyback based one with capasitive coupling be possible to use?
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Postby Capt Ahab » Thu Apr 01, 2004 3:41 am

I don't know about the TV flyback transformer. I don't know enough about HV/HF. I'm just going to build the same circuit that's in Al's schematic. I ordered the parts yesterday. I wouldn't be surprised if there was a cheaper transformer that would work. I guess you would just have to tune the rest of the circuit to match.

About re-inverting the DC into AC. Please correct me if I'm wrong since I'm not a EE or anything, I just have a rough understanding of a few basics. The alternator is 3-phase so how do you hook up a 3 phase power supply to something like a welding torch and the work. Any one phase is only 1/3 the output power but if you combine all 3 phases they sum to 0, not the full output power of the alternator. To weld you need single phase AC. The only way I see to do this is to invert it after it goes through the rectifier. Is there another way? Like I said, I don't know all that much about this. I could try to use only one of the phases but than I'm limited to only 1/3 the output of the alternator. I tried it once and it wouldn't sustain an arc. After I had finished and rewired the rectifier, I realized that I had my battery charger set to only 6V which works fine for DC welding on thin metal but maybe it's just not enough when only using one of the AC phases. Also, I was kind of worried about running a bunch of current through 1 phase while the others weren't doing anything. I was afraid this might damage the alternator somehow.
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Postby sparks » Fri Apr 02, 2004 9:55 pm

You have to use a 3-phase transformer to convert it to 1 phase.
It's just like any other transformer but with 3 primarys, each on its own "transformer-leg".
Gives you the opportunity to change the voltage later if you make a secondary with taps on some windings.

The reason i am thinking about TV-flybacks is the lower current-capacity compared to other HV-transformers.
My OBITs has scared the sh*t out of me more than once when something unexpected has happened.
TV-flybacks can be just as lethal when hooked up to capacitors that gives some current behind but are otherwise pretty harmless.
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Postby Capt Ahab » Sat Apr 03, 2004 2:47 pm

Very interesting. So, is a transformer capable of shifting the phase of AC? I suppose it would have to in order to combine phases, otherwise the electric fields would sum to zero too. How does this work; can you post a drawing?
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Postby sparks » Mon Apr 05, 2004 3:46 am

Well not shifting phase exactly.
This is all from memory since i was a little too quick to answer without having my books available.
Three transformers (or one 3-phase dito) are delta connected on both primary and secondary.
When loading just one phase the currentdraw is supposed to be equal over the phases since they are connected in a loop, but dont take my word for it until i have looked it up.
I tried to draw some curves with 120 deg. shift to see if it looked right but my brain just wasn't up to that kind of fun.
The other one i mentioned with 3 primarys-1 secondary is used on trains for something but i'll let you know as soon as i find some more hard facts.
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Postby Rossco » Thu Apr 22, 2004 12:22 pm

Sparks, im running out of breath!

ive been watching this space and nothing. Get those books out and give me an idea of what is in a 3 phase transformer. I can wind one for myself no worries, and delta config is nothing new to me, but i just cant see the layout in my head yet? Ill get some paper and have a scrible, i might even come up with it myself.
You sound like you know what you might be doing tho so id really like to see some of your ideas on these welders.

Ive been playing with tesla style coil and capacitor today for my welder, I was thinking of full current DC out of the alt for resonating the primary and caps, and the secondary would be the same size and turns going to the torch and work. I was going for super high freqency to see the effect, even tho it would probably only be good for aluminum? If that!
Too much current for any of the spark gaps that i slapped together today, couldnt get a long enough run to see what it would do, if anything, to an arc welder rod.

Those three to one phase transformers, where would one possible be used? and why, is there not three perfectly good single phases that any line powered gismo (comercial) could run of of a single one?
Ill get scribling!
And sparks, while your at it, asuming that you are going to have a look and astound us with your infanate wisdom, would there be any advantage of running the alternator stator in delta config? I know that i can pull more current out of an alternator that was previously wound in star, and that would be an obvious advantage but how would it effect output in the waveform sence?

The other thing that i was thinking of doing is set up a whopper of an alternator that has three separate stators and a LONG rotor, i could set it up to give out three phases of AC that would be three times the frequency at the same revs as a single unit.
When in parralel they would give me good amplitude and current capable single phase AC. I would have to sort some elaborate switching device to dump them sparately into a rectifier for DC tho. and id be going away from the near 100% duty cycle then!
So the solution to this prob. was that in one of my stators (they could not be set up at the higher frequency tho) I invisaged the full set of windings, and it is from this one (not while AC is hooked up) that i could rectify the out of phase AC to DC? Too many variables tho, that i dont know the theory on. What would be the effect on one system when running, would the other be when sittling idle?

Sorry, ive got too many questions that i cant just go and build every one to see what the answer is.
Sparks, im counting on you. I feel that you know a bit in this area, and it would be greatly appreciated if you could chuck it in here in any random order for us to pick through at our own pace. Thanx in advance!

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Postby Capt Ahab » Mon May 03, 2004 4:46 am

Just an update on my welder project.

After building my HF unit I decided to build a few more electronic gizmos for my welder. I wanted a start or continuous function for my HF and I wanted some nice switches to make everything easy to deal with. I also wanted a better way to regulate the field current and I wanted the whole thing in one package instead of a bunch of wires running all over my workbench. I'm in the process of completing it but it's come a long way. On the photos you'll see the control unit on the right that includes the HF unit along with a bunch of other stuff. This project has been severly afflicted with "creeping featurism". It now includes (from left to right) a master power switch, a motor switch, a hi/off/low switch for the field, an "easy start" feature, a start/off/continuous switch for the HF, and a continuously variable current regulator. Also included are a foot pedal control and a rudimentary pulse feature. Everything seems to work pretty well at this point except the pulse feature. I just wired it tonight and I haven't gotten the bugs worked out of it yet. The next step will be to build a more user friendly switch layout and house the entire thing in one portable container.
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Postby sparks » Tue May 04, 2004 2:34 am

I´m afraid i dont have any news more than a short note about 3 to 1 phase transformers.
I asked a friend who went to the same school as i did years ago and he remembered the same thing.
Anyway, a deepdive into his piles of books gave nothing.
There is one more person i can think of that could have some (alot of) info on the subject, and as soon as i meet him i'll ask about his opinion on this and anything else he might have to add.
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Postby Rossco » Tue May 04, 2004 3:03 am

As far as ive got with the three to one transformers is that youll only get a percentage of the power. Its not a phase shift, its only taking one phase out of the three. As far as i understood theres the primary wound in delta config and the secondary is a take representation of two of the windings.

I cant see any advantages of this? In a stator, You could take the same single phase of of two of the windings in delta and get twice the Votage of one but only 1/3 the current of the total out of the alternator.
Im too rushed and cannot explain, but ill do some experimenting in the time till my puter is going again.

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Postby sparks » Tue May 04, 2004 6:22 am

I'm pretty sure the answer is hidden somewhere in the forum-archives at www.diywelder.com But i haven't had the time to read it all.
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Postby tufty » Thu May 06, 2004 8:07 pm

sparks wrote:I'm pretty sure the answer is hidden somewhere in the forum-archives at www.diywelder.com But i haven't had the time to read it all.


And, indeed, it seems that way. Google is yor frend.

Doing a site-specific search (damn handy that) on www.stockly.com elicits the following rather handy-dandy looking links:

http://www.stockly.com/lists/diywelder/0110/msg00013.php
http://www.stockly.com/lists/diywelder/0105/msg00010.php

And espacenet searches for 'alternator welder' were quite enlightening, too. These look handy:

http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=WO03037561
http://v3.espacenet.com/textdes?DB=EPODOC&IDX=US4904841&QPN=US4904841

[/url]
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