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

well, on those things, thers so many paramenters like slip compensation, counter-EMF compensation, DC injection.. all that good stuff.. they're SCR finals as well, which i place alot of faith in..

as far as inductance i can always add a cap or 2 in there to adjust P.F. and bring the voltage and current more in phase, electrically..
shouldn't be that bad.. as far as adjustability, it is infinite being that the core is whats moving and creating a flux variance, instead of, like you said, just tapping various winds on the secondary like they do now..
and i'll follow the 125% rule when sizing it.. i have a few bigass SCRs laying around from some vector drives i worked on that ran 150HP centrifugal pumps in a paper mill. i can always switch SCR units since the PWM boards in vector drives and VFDs are practiacally the same. i think they're just straghforward 3ph ones with no freewhee diode.. no that that actually matters in this application..

counter EMF should only occur on power down and.. well, now that i think about it, theres probably gonna be a good amount on stopping the welding process. i can counter that with an R-C array and some (bigass) snubber diodes i think..

you're bringing up good points tho.. keep doing that..lol

it makes me think.

damn good point as well, 5-0, might hafta look those up.. i know they exist, but no one wants to come off them. i know someone with a gas-powered weder, and theres a freq box on it, but he won't just sell that.. i originally was going to do THAT about 2 years ago..lol.. plus, i get bragging rights if it works, and i learn something..

no education is had in just buying something!! lol :D

JUst move up here and you can use our chit..lol. :-)

Cool idea though...

In the future check out govliquidation.com , and search for any equipment you are looking for. At work I buy a lot of our instruments from there and I have seen lots of welders on there. But don't buy up all of the scopes. meters, or signal generators...I need to buy some of those :-)

You could just jack up your fiddy, and drive a 10 KW generator into the VFD, then just throttle the fiddy to get the variable AC output. A Fiddyrator so to speak. I hope you have an O-Scope when you start powering that thing up to watch the sign waves, your gonna need it!

lol.. got a tektronix at the warehouse, and got about 10 DMM's laying around!!!!

thanks for those sites, Rick and 5-0.. good stuff..

White, another idea! You could drive a 10 hp motor with the VFD, and let that motor spin another motor. Just excite the third phase of the driven motor with capacitors and you isolate your VFD from all the bad stuff. Speeding up or slowing down the driver end, will also vary the frequency............just a mad scientist idea you know! I have seen three phase power derived this way from a single phase source. It has been around for years! Do you follow me?
Oh, I forgot that your after a square wave,,,,,,,,,,Oh Well!

i got ya man!! my welders 1ph, so i could use a transformer to technically tie 2 phases together to create a higher output freq, but in all actuality, i'm going for simplicity.. lol

got a point (again) tho.. but
i'm going t use an M-G set on my perpetual motion thing whenever i get around to that..lol

i've been working on that one for lik half my life, since i've always been a geek and been doing this crap since i was about 5.

i think i've figured out perpetual (endless) motion, and if i can make it efficient enough to carry a parasitic load, either electrically or mechanically, i would have just invented clean, endless electrical power that could fit in your basement.

i'd be stupid rich, then i could fly everyone on here to the bahamas and we'd all go ridin and get something to eat.

mmmmm...chicken

double chicken for you, since i'm drooling over that site now.

you get an atta-boy.

NICE!!!!!!

It is a good site to get cheap stuff, most of our test equip came from there. You can buy a lot of random stuff there too.

yeah.. like "nuclear reactors", "Guns, though 30MM", "Underwater charges", "gfuided Missel components and Launchers"

i like this site.

alot.

world domination's a click away!!

I have some really cool perpetual motion ideas, but it will cost you the Fiddy........LOL. No seriously, I have studied the M-G scenario for a while myself, but also have another most interesting way of creating power output with very little input. We need to get together, smoke one, and brainstorm dude!

lol.. i KNOW superconductors are the key.. that, and magnetic bearings...

i got it man.. just need funding!!!!

What about the Flux Capacitor? :)

i thought of that, but i can't get that thing to 85MPH!! ;)




lol.. in all actuality, a cap WOULD change the flux in the transformers core.. so, it does exist!

Thats 88 mph. :)

ahh.. yes. good call bro.

who the hell did you find my site????

i got connections.. lol

world domination, man.. it's gonna be awesome.

serously though, what link?

sounds like you could basicly take 2 motors, one the drive off a/c current - one would be rewired to be used to switch polarity being fed by the stick welder.

in an M-G set, yes. you can use whatever you want for the motor, whether it's DC, AC or whatever, and MAKE whatever current type you desire. you can technically make 12VDC into 480VAC 3 phase power.
thats how rotary phase converters work.. theres two types on that, static (using capacitors) and dynamic (using an actual 3ph. generator)

but as far as what i want to do, i'm looking to build a compact "power supply" of sorts that will convet my stick welder into having high-freq TIG capabilities.. since transformers transmit their input noise and transients to the output, that shows that ifyou'd power a transformer with oh, lets say a sawtooth wave, then you'll have a sawtooth wave on the output. if you ran a squarewave into the primary, you'll get a squarewave out of the secondary.

therefore, if i use a variable freq industrial motor drive, (which pretty much generate squre waves) i can modulate the output from the welder depending on the drive settings. if i wanted to run the welder at 120Hz, just go into the parameter and punch in 120. if i wanted 225Hz, same deal. they're good for about 400Hz, depending on the model.

the square wave is really important in TIG welding evidently, so i'm gonna try to maintain that waveform as an input to my welder.

For a moment I thought I was reading a Worlok post... :)

Hendrix,
You may want to use a shielded transformer, so the natural eddy currents in the transformer will be at a minimal level,and will keep your sign wave cleaner and more true to form with the square wave output of the VFD.
And we are the most supreme wiring, designing and fabricatin MO-FO's of the universe, "the Man" x 2! ( just for the Srob..........LOL)

"You see Vern the problem is your catastrophic converter" Know what I mean Vern?

http://jimvarney.org/ernest.jpg

Ha Ha, old Ernest T, havent seen him in a while!

lmao, sro and deej!

ya sro.. i'm the man. i can't help it.. some ppl are just born that way!:D

i've been hacking things apart since i was 4.. surprisingly, i've been putting them backtogether in various conditions since about 5 or 6..;)



worlok!!! .. c'mon man!! the only sine wave there will be will be going into the VFD from the wall outlet! lol

its all modulated waves from there on out bro...

i do believe the welder is pretty shielded.. its got a copper wrap around the windings and its enclosed in a metal box thats grounded.. RF alone will not transmit.. not sure if you've ever studied the effects of EMP and RF transmission, but they don't like metal. i almost went to get an electronics engineering degree on top of the electrical, but i just don't have the money!!

but ya.. the vfd itself will be uber "clean" since they're designed to be installed in sealed cabinets with other electronic things.. you ever see inside a big vector drive? EVERYTHINGS wrapped in copper and grounded out..

Not be a buzz kill or anything, but I dare say that you will be better off to just go out and buy a purpose built TIG welder. You'll most likely spend less money than what you will on this contraption especially when you factor in all your time, burned up parts, and trial and error. And it will actually work. :) Not to mention, you will have it immediately and can move on to your actual project, instead of gearing up for your project and I suspect building a working welder may be a never ending project, you will always be tweaking, fine tuning, trying to get it right, just one more adjustment, etc, etc.

Don't get me wrong, I build a lot of custom things. But I save my valuable time and effort for those things that only I can do. If I can buy a machine/service/information that already exists and does what I want for a fair price, then I'll choose that option every time, unless I just want the learning experience of doing that particular thing, but then that's a whole other thing though with a different cost/benefit system.

But my advice is that if you need a TIG welder to use as a launching platform for your other ideas, then don't waste your valuable talent building the welder. Get a loan if you have to and buy the best one you can afford that does what you need. Then USE it to launch your ideas. And then sell those ideas, inventions, services, etc for a profit and pay for the welder 100 times over.

On the other hand, you could easily spend as much on a home made welder, work on it for months, and it may never work adequately. At the very least, you have lost valuable time where you could have been turning a profit using your machine than if you had just bought a decent Miller or something.

THINK! Where is your unique talent that no one else but you can do? Is is building the welder? Or is it with what you can do with the welder?

well, you definitely have a point..

oh i'd 100% most certainly by a TIG and a plasma cutter and all those goodies, if i could get a loan, had credit, or money!! man, i'd LOVE to have a brand new 350 synchrowave in my shop with a water cooled torch and a thermal dynamics uber plasma cutter sitting beside it, but, i'm poor..lol

i'll have it eventually.. i'm just always curious as to if i have the capability to do something outlandish as this. if i had to go buy a welder, and buy this and that, absolutely the cost would offset quickly and i'd be paying more to build a questionable rig than to purchase proven technology, but in my theory, i do believe it'll work.. this is basically just to get me by, and i won't be welding a customers machine with this.. if it works, great!! if not, then i've experimented and learned something, which, to me, in itself is far more valuable than purchasing someone elses brilliance.. as you've already noted.. lol

you are certainly right tho.. but like i said.. if i had the money, i'd have everything i need. i appreciate your input tho!