Ok so why am I not seeing it?

[Starwoes]

Commercial welders are sometimes very cheap these days. In light of the many outlets that they can be purchased for a significant savings off the new msrp, I can see why many of you DIY guys aren't building any of these things from scratch.....but,

I was bitten by the bug and decided to look for circuit diagrams to build one. I haven't found much and the ones I came across are basically a normal power supply (AC => DC) where line voltage is being converted to about 10V - 40V with a huge resultant increase in amperage. Is it really that simple? If so, why the lack of interest?? Not worth the bother?? Risk of ELECTROCUTION deterring folks??? Heck I'm still trying to figure out stepper motor control...and it's tough going but here is something that looks much much easier.

I'm looking for additional info on this so please provide links and anything additional that that helps.

[Al_The_Man]

What type of Welder? Stick? or MIG?
The stick welder requires constant current source and the MIG constant voltage, you will find that the stick welder transformers have magnetic shunts the often can be cranked in and out to cause the voltage to regulate depending on weld pool resistance.
Al.

[Starwoes]

Originally Posted by Al_The_Man What type of Welder? Stick? or MIG? The stick welder requires constant current source and the MIG constant voltage, you will find that the stick welder transformers have magnetic shunts the often can be cranked in and out to cause the voltage to regulate depending on weld pool resistance. Al.

Hmmm, so it gets deeper. I'm talking about a welder where the electrode does not get consumed. I guess GTAW or something. What does constant current get you as opposed to constant voltage?

Al_The_Man, if I got this right, because the stick needs constant current, they are regulating voltage to keep current at the same set level??

[ynneb]

The questions I would be asking are how do they make those electronic (transformerless) welders ? They are usually very expensive. they would be the ones I would like to build.

Also while we are talking DIY welders, I would like to know if it was possible to use the transformer off an old welder as a one of the components for a DIY plasma cutter. What Is the difference in power they deliver, the both melt metal?

[JPMach]

The new transformerless welders use inverters (just like the spindle drives on CNC machines) to deliver constant current or constant volatge depending on what mode you select. The ones I've seen will run: stick, tig, mig, pulsed tig, pulsed mig, and carbon arc cutting. All you have to do is buy all the accessories such as the wire feeder for mig. I would love to have one some day, I hear the arc off one of these is awesome!

JP