Making my own welding machine?

Yup, I recently got a Lincoln Square Wave TIG 300, and am learning to use it. Steel was pretty easy, but the aluminum is a good deal trickier. But, I have made a couple test welds on aluminum that started to look pretty good! Fascinating machine!

Jon

On Tue, 04 Jan 2005 23:29:35 GMT, "Tom Gardner" calmly ranted:

We know what YOU want it for, Tom. You want to go back to the point in time just before the perps came out of your shop so you can kneecap 'em, don't you?

(Let me know how it works, Iggy!)

-- "Menja bé, caga fort!"

I got to get a bunch of new stuff! I doubt I could hurt anybody over stuff, it's just stuff and it doesn't go on the score card.

Its just Stuff that represents your time, your labor, your blood sweat and tears. That accounts for a lot. It does for me anyways.

Just my opinion of course.

Gunner

"Gunner, you are the same ridiculous liberal f--k you ever where." Scipio

I thought that welding transformers were built with a large leakage inductance, so that the arc is struck with a higher voltage, which falls to

10-15volts as soon as the arc strikes. I believe a power transformer would not behave like that - a transformer with good regulation would burn out in seconds if it were used for welding, unless there were some current-limiting in circuit.

Perhaps somebody who knows could enlighten me?

G.H.Ireland

They are built like that. A separate variable inductor could be used for current control in series with a normal power transformer to give the same 'nominally constant current' effect.

Mark Rand RTFM

Lindsay Publications had a little book on making your own welder, I didn't see it on the website but maybe it's in the catalog:

Ken Grunke

I don't know about that. Welders do use wide flat 'wire' and complex cores. I know for more years that I want to think power transformers have been used as welding transformers. You are talking about open circuit voltage vs. closed circuit. Regulation is the name and efficiency is it also. Once HV OSC's were or'd into the main work lead, that need went out the door.

Pure stick likely needs it. Stick with a fancy HV OSC like TIG would be just fine.

That is my take - Martin

Err, so TIG doesn't need a current-limited transformer?

Tim

-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @

For what purpose - just to generate an arc - no, most have built in OSC circuits. Current is always limited by the core and by the work rod.

I think what you refer to is the current surges that generates the high voltage spikes of a winding field dying and generating a voltage spike. That isn't needed.

Tig is generally constant voltage and varies the current over wide ranges. It is an electronic controlled circuit - not just a simple transformer with tight or loose windings.

When talking welding - it can become more Physics and Electronics today than just 10-20 years ago. Some stuff is newer than that.

Martin

Well, modern (inverter) devices I'm sure do. Sort of like this:

big link. It's the welder schematic on dansworkshop.com.

...Only more complicated, err...sophisticated!

At any rate, current into the arc has to be limited, due to the electonic nature of the arc. Arcing with a fixed CV transformer is a sure way to blow a breaker (with exceptions like MIG, but that's not really a constant arc, so there :P ).

Tim

-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @

Yes, but a ferro-resonant transformer as shown does current-limit. If the cross-leg were sawn and made adjustable, it might behave a lot like an arc welder.

Yes, it does. TIG and stick have essentially the same electrical characteristics. They are called "constant current" or CC machines. They are not necessarily electronic, e.g. Miller Dialarc HF.

A V vs I curve with varying resistive load would look like the first quadrant of an ellipse. Voltage is fairly flat at the top (open circuit, high load resistance) region, but the curve is nearly vertical (constant current) near short cct condx. OCV is typically 60 to 80 volts, arc voltage is typically about 24 volts.

This sort of VI characteristic is also typical of oil ignition and neon sign transformers. It is achieved with leakage inductance in the xfmr (often just a magnetic shunt), though welders do sometimes have additional inductance as well.