Mad Scientist Time
 

Ok. you guys know i do all this electrical crap, and fabrication crap, and that i'm the man.

lol

well, you also know that i'm not only poor white trash, but i'm also poor. therfore, i can't afford a $2,500 TIG welder to fix nd make stuff at the shop, so, with a little research, i've become pretty confident in the feeling i can make one.

you CAN make a "scratch start" TIG rig with just a torch and a stick welder.. BUT, you can't weld aluminum.. gotta weld that with AC, and the frequency is usually high or variable, which makes a uber difference in how aluminum actually welds..

so, in my theory, i can use a (single phase) motor drive to power my stick welder.

standard TIG rigs use "square wave" outputs, which, instead of exponentially rising and falling to a 0 value before transitioning to the opposite polarity, the square wave INSTANTLY switches to the opposite polarity.. that instant switch allows a better weld to be had, and if i'm welding aluminum on my stuff or anyone elses, i want the best welds i can get, obviously..

i'm confident tho i can make a big boys type welding machine without spending big boy money, which i don't have..lol

VFD's in industry typically produce square waves after their inversion stage.. it's just about mpossible to produce a perfect sine wave with electronis, anyway.. theres always gonna be a bit of ripple and squared off curves in it...

so, theres why i can think i can do it. i have variable frequency control, and i have square waves for an output from the drive...



so, what do you guys think?

I read that and just realized how much I don't know. :( "I'm not worthy, I'm not worthy."

Maybe I am not reading this correctly but do you plan on feeding the output of the VFD into the primary side of your AC welders transformer, or straight to the stick. Also I am wondering how you are going to feed the wire. I believe argon is the sheild gas of choice for tig or mig if I am not mistaken.
Knowing you, I have confidence that you will figute it out!

nah deej.. you're worthy man!! you DO have the ability to learn it just as i did!! lol

theory is easy. it's applying it thats tough, sometimes.

As soon as I can afford it I'm buying one of these machines. I had my blinker fixed last week by a guy, it took him less than 5 minutes and he charged me a minimum of one hour, $60.00 That's the last time I have someone else do any welding for me.:mad:

>>>>>>> Wire feed machine

yes worlok. i'll feed the primary.. that way, i'll still maintain the variable current aspect, and the welder itself has DCEN, DCEP, and AC on it. its an old 230A craftman stick welder. i'll buy a TIG torch, power block, regulator and gas. it's worth it for $200 new..

the transformer is whats variable- movable core.. old skool.

but transformers are always power in=power out, so i know if i manipulate the frequency to the primary, the secondary frequency will follow at 1.1 with respect to lag and lead.

no wire feed, tho you bring up a neat idea..

yeah deej, bro, you got raped. then again, maybe THATS why i never make the money i should! i woulda done that kinda fix for free, or for someone i don't know (off the street) maybe $10..

MIG welders are awesome.

Yeah White, I was thinking it may be a multi tap tranny, but the movable core type would give a more infinitly adjustable output, which your going to need on a peiced together rig like that.
You are going to have to be really careful not to overload the triacs or transistors, whichever, in the VFD. I would be sure to fuse them just under their rated current output in order to keep from toasting them. I'm sure you already thought of that but am just trying to help dude!
One thing I do know, is that VFD's do not like a lot of counter inductance, That's why we use the sheilded motor leads on the later models. And with feeding a tranny instead of a motor, I am just wondering how it will tolerate the primary impedance of the tranny, versus the normal impedence of a an AC motor. Could be negligable?

I just read that man and haha I think I just learned something today, but I say GO FOR IT and PICS PICS PICS lol :)

Why don't you keep an eye out on ebone for a add on high freq box. Heres a link to a thread about it. http://weldingweb.com/showthread.php?t=23252