DIY--TIG Welder

[OrganicMechanic]

Alternator modifications:

I like and chose the Delco cs144, there is lots around, parts are cheap and you dont have to solder anything(original stuff). You can use almost any alternator. The theory is the same, but I am only dealing with this alt.

Ive always used the 140amp version, the more power the better

Anyway, there is a rectifier inside that changes the current from high frequency three phace AC to high frequency DC. But the original rectifier lets the smoke out the second you try to weld through it. This is becuase it has avalanche diodes and I believe they are set up to blow if the volts get to high. Simply as a safety measure for your cars electronics.

You have to take the alt apart and replace the rectifier with a Transpo Part# dr51173 Rectifier. It works like a charm

Also take out the regulator, and throw it in the garbage.
Next, Solder a wire to the terminal where the regulator was attached to the field coil brush. And run that wire outside of the case.
I drill a small hole, slip the wire through and JB weld it in so it doesnt move around. and put it all back together. You can clock the case around as well to move the post to the best spot.

and mount it on your engine/electric motor

now you have a power supply.

put 12V in the wire you just installed and you have welding current.

the easiest way to use this is to install it into a vehicle.

Go and buy a ford external regulator about $10

I can't remember the the letter designations right now but you run one wire to it that is turned on from the ignition key to power it.
On wire straight from the battery, so it can sense the battery voltage, and one to your new wire. that one runs it. On the regulator there is an extra terminal, you dont need it but you can use it to run the charge light in your dash.

once thats all hooked up you just hook the Batt. terminal to the battery. and now you have a very nice 140 amp 12v charging system for your vehicle.

Now all you have to do to weld is take the batt. wire off of the battery, and hook up your stinger....
!!!straight from the batt. terminal on the alt to the stinger, nowhere else!!!

and a negative clamp to the vehicle chassis.


Run the engine.

I hooked up a hand throttle by using a bicycle gear shifter to the throttle, in order to idle up and set the RPM. the faster the engine the more power you get. and that's how you set the heat. if you rev it up to about 3500 you can run angle grinders and brush motors.


What happens is the regulator thinks that the alt isn't charging (becuase the output isnt hooked up to the car 12v+), and it puts out max power to the field coil. I swear it is the best arc welder I've ever used, the HFDC is super smooth and burns nice and deep.

We now have a power supply.. modified alt, and a electric motor.

We need to power the field coil with adjustable voltage.. so we can adjust the welder as we need it.

Becuase all we have in the new welder is 208VAC to run the electric motor..

(You may have 240VAC or something else... whatever )
We need to find a way to make it 0-12VDC

So I got a step down transformer fromt the local electric supply.. you can see it in that pic, its the big blue box.

It has two seperate input coils, and two seperate output coils

they are wired in series. 208 VAC in one side and 25VAC out the other

Getting closer I know have 25VAC....

[OrganicMechanic]

Ok, so far this is for DC welding only wich is limited to welding everything except for aluminium. there is AC there and I plan on using later on, but for now lets just talk about DC.

For all TIG welding you need Argon. so you will need a tank filled with argon. a regulator with hose, a tig torch, and that special fitting to attach the gas hose to the tig torch,it then bolts onto the welder conection

so I left of at 25VAC, next we need to change it to DC with a simple bridge rectifier.. you can see it above the transformer, it is the small square box with four wires screwed to the aluminum plate... ie heatsink



now we have a DC power supply to work with. simple hey

its get a little more complicated from here..
next we need to talk about transistors....

A transistor is sorta like a valve


it has three terminals.. Base, Collector, and Emitter

The collector is where gets its power from. IE: the DC output from the Rectifier

The Emitter is the output, pretty self explanitory

and the base is the handle of the tap basicly.. its sets the output...

ok another background lesson.... voltage dividers

kinda tricky but really very simple

A voltage divider is a way to use less than the maximum output voltage.

if you take the negative of a DC power supply and the positive of the same
DC powers supply and put two equal resistances between them in series, and then attach a wire to the connection between the resistors you will get half the voltage of the main output. like this




the +Vs is our 25VDC positive output

the OV is our Negative output

and the output Vo would be 12.5VDC+

Make sense??

to make this usable and adjustable we use a Potentiomer as a variable voltage divider this is what controls the base voltage on the #1 transistor

a variable voltage divider using a potentiometer looks like this:



if you look at it as if the middle connector.. known as the wiper is right in the middle we would see half of the output voltage on the wiper connection..

as we move it closer to the negative side we would see less volts down to zero. and if we move it to the positive side we would get more volts all the way up to the 25VDC max +


so with this we have hooked up to our DC power we now have a variable output voltage from 0 to 25VDC.

the problem now is that a potentiometer will only take a small load before it burns up.. this is where the transistor comes in

how are we doing.. you guys learning this stuff??

So,

we now have the variable output from the Pot.

the variable wiper output goes into the Base of a TIP3055 Transistor you can see it just below the rectifer on the aluminum plate.. both the rectifer and the tip3055 have heatsink grease on the back so it will dissapate any heat better.

Here is a pic of a TIP3055 there are only a couple bucks at an electronics store



But yet the tip does not have enough current carrying ability to serve the field coil reliably yet, so it controls the base input of two 2N5885 Transistors in parrallel.. you can see them on the right, they have there own heatsinks, and I got them used from the local electril suppy store for about $5 each.



the output form the 2n5885's are run through about 12" of 14 AWG wire to act as a small resistance to balance the load between them.. before there are joined and hooked to the field coil wire. you can see those wires as the red wires that are coiled up.

Also when i was inside the alt I ran the negative field coil brush terminal out of the case as well, so it is isolated from the welding output and is connected directly to the 25VDC - output. simply a safety measure to protect the electronics

with this all hooked up you know have a variable welding supply controlled by a pot.. you can see the main power control pot sticking out of the back of the welder on the right hand side.

Becuase Volatge dividers work on resistance and there is so much wire the 25VDC we started with max's out at the field coil input at about 18VDC wich is great as all it needs is 12VDC. but I like ot be able to crank it up that extra little bit..

But!! if I was hooking this up to a 240VAC wall input I would end up with more power there and might have to limit it a bit so not to have a melt down.. I am at 208VAC input so we are good to go.


next up foot pedal control

[OrganicMechanic]

VR1 is the Max power control and VR2 is the foot pedal control


VR2 is a sliding pot I canabalized from a sliding light dimer switch.

[OrganicMechanic]

Resources used--

http://www.hotrodders.com/forum/my-diy-tig-welder-77730.html

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

http://diy-welder.com/index.shtml

enjoy!

[Jesse30]

THAT IS AWESOME.


seems dangerous but VERY awesome.

[Zmann42087]

That's pretty crazy.. nice work. I'm going to stick (err.. TIG) with Miller though.

[wolfgangstbd]

omg that is badass but i wouldnt trust it ahha.. since my friend has a tig just layin in his garage ill stick to that

[Kerrath]

That's pretty damn cool. Poor man's tig welder (assuming he has a massive motor and a spare alternator). With all those bare terminals though, it looks like a disaster waiting to happen. I'd be scared shitless to use a TIG welder I built myelf.

[Justin B]

This has got me thinking. There's several DIY's out there and some are nicer than others. If I can find a cheap 5 hp electric motor I might have to make one. Here's a nice one-

http://myweb.cableone.net/rschell/TIG.htm

I just wish that he had finished updating it when he started using a microcontroller. The previous designs would still work though.

[dashboardmonkey]

seems dangerous BUT THAT'S WHAT MAKES IT VERY awesome.

Fixed that for ya

[atomic]

[itsbrokeagain]

lol@ burnin down the house

[Unearth078]

organicmechanic, u need to throw a disclaimer on that lol. im going to have to start hacking away at some old air compressors

atomic is the fucking man btw

[Hellabad]

I dunno. I was already pretty impressed when OrganicMechanic made his own banner at mybannermaker . com

[OrganicMechanic]

I dunno. I was already pretty impressed when OrganicMechanic made his own banner at mybannermaker . com

coming from a tool who has none.