DIY TIG Rossco style & other tools

[Rossco]

Right im sick of the Stic/arc.

Im gonna build myself a TIG.

Sorced all that i need today.
Torch is $160
Tungsten Ceraited or Thorium are about $2 each
Argon is about $80 for gas and $100 per year, hire
Alternator is from my workshop, and mower is where ever i can find it. Ebay?

Total, about $400. Not bad considering a comercial unit will set me back about $2'000 to .....$20'000!
(Au$)

Method:
Get mower
Take blades off, mount pulley, sized to give me about 5000 prm at the alt
Cut hole in front of mower case, mount alternator, belt adjustment brackets and belt
Hook up solid state votage control for field circuit
Attatch torch and cables
Mount bottle bracket and bottle
Weld something!

Questions?
Comments?
Dissagreements?

[Rossco]

Ive done more thinking on the TIG.
Its all of a sudden not such a simple set up.
Im thinking of putting HV overlay in, not to hard, hopefully for easy start up.
But what is starting to complex my design now is the idea of pulling high current single phase AC out of the thing. This would either involve a phase shift if there is such a thing, that lines up all three phases! Or go three separate stators with a single phase each opperating of a single field rotor. This could directly drive the torch for all AC needs, and for DC one of the stators could have all three phases in it, running through a normal rectifier set up.
I dont think that either would effect the other if they had a separate torch fitting for AC or DC?

Now, why cant i use 3 phase AC? Im sure that i read somewhere that i couldnt, but i dont recall at all why? Cant believe everything that you read can you! I need proof, or reasonable arguments to the contrary!

I think that taking into account that i havnt ever actually used one before, let alone built one, i better go with the simple design first and work my way up when i get a feel for what i need!

Another tool to my colection comming up too!
Sheet forming slip roller.
I made a rough one that i used for my last engine, and it worked great!
It was simply angle and pipe welded together with some legs clamped to my ute!
This, i think from my first model, will be the ideal.
Any suggestions?

Rossco

[Mike Everman]

Ross- Look below at the "homemade tig welder" thread; everything you might want to know, I think.

[larry cottrill]

Now, why cant i use 3 phase AC? Im sure that i read somewhere that i couldnt, but i dont recall at all why? Cant believe everything that you read can you! I need proof, or reasonable arguments to the contrary!Rossco

Rossco -

Do you mean three-phase out to your torch and work? Um ... I hate to say this, but there is no such thing. You can't have three-phase on two wires. Three-phase basically has one purpose: to efficiently drive motors that are designed for it. I suppose you could conceivably have a transformer with three-phase on one side and single-phase on the other, too, although I've never seen that.

Any 'split' from a three-phase setup [using two of the three wires] is a single-phase circuit. For axample, if I remember correctly, a 480-volt 3-phase service will enable you to tap into it as three 208-volt [NOT 240V] supplies. That's why so much equipment is labeled '240/208 Volt Single Phase' -- because in a lot of factories, and even businesses in industrial areas, the single-phase power is actually derived from a 3-phase source.

L Cottrill

[Rossco]

Yes Larry, i put that wrong.
I mean two lines out, one to the work and one to the torch.
What i meant about the three phase is the wave overlayed each other directly from the stator of the three phases, but now that i thinkabout it (thankyou) If they arnet rectified seperately they will nearly compleatly cancel each other!

How do i go about re inverting the DC then?

How about this mower?

Rossco

[Rossco]

Desruction Testing!!!!


I got some spare time to myself today. So i had a play with a couple of alternators.
I leant/realised several important things for my TIG.
I ran up a 45A alternator i had in the scrap bin that i know worked. I took out the pin from the regulator to the brush and extended a wire out as to be able to control the voltage.
I did all tests in my alternator and starter test bench that has a whaping great variable rpm elecric motor.
For these tests i didnt bother with any field voltage control, i just relied on rpm control.
I reved her up and gave it full field. Made a fair spark at the field wire.
Not thinking any further of this i gave it full revs and dropped the thing in again. Booted me REAL hard through the plastic of the field wire.
At about this mom i thought about it a little more. The alternator is a Bosch unit with an internal reg that is actualy mounted on the back of the alternator. These switch field negative. The positive for the other field brush is from the exiter diodes (D+). This i thought would be nice on my Moweld, as i could vary the field current without an external power sorce.
But, it also led to this alternators demise! when running full tilt, it was nearly 100V (over what my test bench reads to so thats a bit of a guess ill get a better reading next time) Problem with this is that this is also what is going to D+ and with full field this also over the field circuit. At 100V this is 25A, its designed for 3A!!! didnt last long.

I struck an arc, at full revs and held it (after going and getting a welding helmet and trying again). I pulled max current out of the thing, WELL over 45A with that sort of field current, more like 200 or so!
I burnt through most of the 1/4 inch steel rod that i was using as an electrode before the thing packed it in. Great fun! And quiet, i was expecting for the alternator to howl like one that has the diodes shorted or blown! The arc sounded great, a constant hiss, very very hot! and nearly too bright for my stick welding welmet!
I dont know why i didnt try a proper welding rod first!

Anyway, at the end of the day, when it had cooled off enough, i stripped it down and checked out the damage.
NONE
well, the rotor burnt out, and all shorted together but that was expected at 10 times its design limit!
Diodes, solder joints and fields were all like new! Well, as good as they came out of the car!
All the heat and smoke came from the rotor.
Really good results!
Ill get a bigger alternator going soon and do some stick welding with it, see how well it does it and how it takes it (then ill probably fry some rod again with increasing (measured) field voltage and see what its actual limit is.

Rossco

PS Thisarvo the customer of that alternator wanted the old one back cause he didnt think that it was faulty! LMAO (the reg was faulty in the first place tho) Really is now tho!

[Rossco]

Hey all, good news.

I got another old alternator running this arvo.
It is a 55A Bosch unit very similar to before.
At full revs of my test bench, at a field of 12V it outputs 140V Capable of 55A. (im assuming that current, i will have to test this later)
With a field of 24V it outputs 250V, and capable of 110A.

The rotor took the 24V no worries. No overheating or damage at all this time. But i suppose its also not 100V or so that it was before.
I chewed through about 5 rods of different sizes without a worry.
At the end i could still put my hand on it, it was reall warm, but not TOO hot!

Some pics of welds. Sorry, not the best welds, i was in a hurry and not too worried about asthetics.

Its got a great hissing scream to it, unlike my bought house power arc welder, that groans and rattles.
Its soooo much easier too. No sticking to the job, easy start up, dont even have to scratch start it!
Ill get the HV overlay into it soon and see how much difference that makes.

I am happy stuffing around with bits and pieces for the mom. Im finding too much out still to just jump in and build the final model. For once im trying to get the concept right first.

I would recomend anyone to go and build one of these even if its just for stick welding! (im pretty happy with it already) Cant wait to get my tig stuff!

Rossco

[Capt Ahab]

Rossco,

I've been TIG welding with my welder using mostly the 6V setting on a battery charger hooked up to the field through some homemade wirewouind resistors. I haven't measured the voltage actually going to the field but it is less than 6V. This works fine for thin stainless and usually I have trouble with it being too hot rather than too cold. I can use the 12V setting and turn down the resistance for welding heavier stuff.

The other night I adapted my wirewound resistors to a foot pedal and it works great. You can start the arc with higher power and then back off quickly to almost nothing. I also have my HF unit working nicely which seems to keep the arc going down to lower currents than would otherwise be possible.

I've been messing with my rig for probably a couple of months now and I still haven't packaged it up to a nice final product. I keep learning new things and incorporating them. Right now I'm working on a way to have HF only for start or on constantly. One problem I've run into with the HF unit is that it messes with other electronic control circuitry I'm trying to use. I'll have to figure out a way to shield it I guess.

I'll post some more photos when I get my camera back. The wife took it with her on a trip.

[Al Belli]

I built a HF control and Argon postflow circuit assembly which works if You do not have the HF operating.
As soon as the HF comes on, the 555 timers lock up and do not shut off.
I have even tried isolating the inputs and outputs using electromechanical relays, and that did not work. After much experimentation, I have abandoned the electronics, and am going to use electromechanical timers
like the commercial units use.

Al Belli

[Capt Ahab]

I had the same problem trying to use a 555 to control a relay to pulse the arc. Actually, the 555 wouldn't lock up, it would just change the timing and make it inconsistant. It looked like a problem I could overcome but I lost interest in the pulse function.

Al,

Do you ever use your TIG and HF setup with your AC welder? I tried this also with a cheap AC welder with very poor results. I was wondering if it was just my crappy welder or if there is more to it than that.

-Ahab

[Al Belli]

I have not used My tig setup on AC. It should be ok on AC.

Al Belli