HF Mig-mag welder
Dr. H., Wed Feb 04 2009, 06:49PMGood day guys
I have been working on this project for a few weeks now (when I have time) and I finaly got it working. It is a just HF inverter based on the sg3525. It consists of a full bridge of irg4pc50ud IGBTs, the transformer consists of 18 primary and 2+2 secondary turns. The electronics is as simple as it gets - just variable puls width, no feedback, the output is boosted with UCCs, few seconds delay to charge the filtering caps up to voltage and a OCP (something like the one used on DRSSTC - it shuts the whole thing down if it exceed the current in the primary).
Here few pics:)
Re: HF Mig-mag welder
..., Wed Feb 04 2009, 07:02PM
Wow that looks really nice!
You know that you are getting good when making a smps mig welder is just a simple project done in your spare time
..., Wed Feb 04 2009, 07:02PM
Wow that looks really nice!
You know that you are getting good when making a smps mig welder is just a simple project done in your spare time
Re: HF Mig-mag welder
Proud Mary, Wed Feb 04 2009, 07:03PM
Good work, son!
Proud Mary, Wed Feb 04 2009, 07:03PM
Good work, son!
Re: HF Mig-mag welder
Dr. H., Thu Feb 05 2009, 06:01AM
Thanks for the kind words guys :)
Dr. H., Thu Feb 05 2009, 06:01AM
Thanks for the kind words guys :)
Re: HF Mig-mag welder
Arcstarter, Thu Feb 05 2009, 07:49AM
Wow, very nice! If only there where less gangsters and rapists in the world and more smart people like you and the rest of 4hv :P. When i have more electronics knowledge, i think i might try this.
Arcstarter, Thu Feb 05 2009, 07:49AM
Wow, very nice! If only there where less gangsters and rapists in the world and more smart people like you and the rest of 4hv :P. When i have more electronics knowledge, i think i might try this.
Re: HF Mig-mag welder
101111, Thu Feb 05 2009, 12:39PM
I really enjoyed this project, everything with it is just so damn neat.
Would be great if you made a good and thorough project thread about this.
101111, Thu Feb 05 2009, 12:39PM
I really enjoyed this project, everything with it is just so damn neat.
Would be great if you made a good and thorough project thread about this.
Re: HF Mig-mag welder
Dr. Dark Current, Thu Feb 05 2009, 12:42PM
Very nice.
-what do you use for the transformer core?
-how do you limit output current? (leakage built into transformer/external inductor?)
Dr. Dark Current, Thu Feb 05 2009, 12:42PM
Very nice.
-what do you use for the transformer core?
-how do you limit output current? (leakage built into transformer/external inductor?)
Re: HF Mig-mag welder
Dr. H., Thu Feb 05 2009, 03:24PM
Good day guys
again thanks for the kind words !
Dr. Kilovolt - for core I use three sets of E80 cores (a bit of an overkill but they work great).
About the current limiting - if I directly short the output of the SMPS the over-current detection kicks in (the leakage inductance is not enough). Mig-mags are a little bit fifferent from stig welders. The current is limited by the resistance of the thin wire that comes out from the nozel -it's speed and thincknes - bigger the speed and thikness bigger the current. Afcourse in big deal it depends from the output voltage of the inverter.
(I don't know how to explain it better).
Cheers :)
Dr. H., Thu Feb 05 2009, 03:24PM
Good day guys
again thanks for the kind words !
Dr. Kilovolt - for core I use three sets of E80 cores (a bit of an overkill but they work great).
About the current limiting - if I directly short the output of the SMPS the over-current detection kicks in (the leakage inductance is not enough). Mig-mags are a little bit fifferent from stig welders. The current is limited by the resistance of the thin wire that comes out from the nozel -it's speed and thincknes - bigger the speed and thikness bigger the current. Afcourse in big deal it depends from the output voltage of the inverter.
(I don't know how to explain it better).
Cheers :)
Re: HF Mig-mag welder
ConKbot of Doom, Thu Feb 05 2009, 05:45PM
Very nice, I take it by HF you just mean the inverter, and youre outputting DC? or is your inverter a pulse arc type mig welder?
What kind of voltages/currents can you output?
Did you buy a wirefeeder?
Pulsearc mig is really nice to use.
For those who dont know about regular mig, it just holds a constant voltage across the terminals, and the constant voltage keeps the arc length constant, as the wire feeds, arc length drops and current increses, melting the wire back and transferring the metal.
As far as welding technique, as you move move the tip in circles, similar to drawing an inductor symbol (the loopy style, not the one with just humps), like this Slow down as you get to the bottom of the loop, and speed up as you get to the top where the lines cross. Doing it like that will give you the "stacked coins" appearance since youre advancing, slowing down, advancing... The side to side movement of looping helps get a proper fillet on the edge of the bead. Though the whipping doesnt have to be pausing at the bottom and advancing at the top like the symbol I posted, whatever works for you.
Also, you can 'push' or 'pull' the puddle as you weld. Pushing is having the gun pointed so that youre 'pushing' the puddle forward, and then obviousley, pull is pulling the puddle forward, both work, most people have a preference though. Just make sure you can see the puddle however. :)
Nice work, cant wait to see some other stuff made with it :)
On the two samples you posted I would also turn the 'heat' up a bit and definitely whip more as you move.
ConKbot of Doom, Thu Feb 05 2009, 05:45PM
Very nice, I take it by HF you just mean the inverter, and youre outputting DC? or is your inverter a pulse arc type mig welder?
What kind of voltages/currents can you output?
Did you buy a wirefeeder?
Pulsearc mig is really nice to use.
For those who dont know about regular mig, it just holds a constant voltage across the terminals, and the constant voltage keeps the arc length constant, as the wire feeds, arc length drops and current increses, melting the wire back and transferring the metal.
As far as welding technique, as you move move the tip in circles, similar to drawing an inductor symbol (the loopy style, not the one with just humps), like this
Slow down as you get to the bottom of the loop, and speed up as you get to the top where the lines cross. Doing it like that will give you the "stacked coins" appearance since youre advancing, slowing down, advancing... The side to side movement of looping helps get a proper fillet on the edge of the bead. Though the whipping doesnt have to be pausing at the bottom and advancing at the top like the symbol I posted, whatever works for you. Also, you can 'push' or 'pull' the puddle as you weld. Pushing is having the gun pointed so that youre 'pushing' the puddle forward, and then obviousley, pull is pulling the puddle forward, both work, most people have a preference though. Just make sure you can see the puddle however. :)
Nice work, cant wait to see some other stuff made with it :)
On the two samples you posted I would also turn the 'heat' up a bit and definitely whip more as you move.
Re: HF Mig-mag welder
Dr. H., Thu Feb 05 2009, 09:42PM
Good day guys
Really good article ConKbot and thanks for the explanation. About the welding - I am not a welder - my father is. I was just demonstrating high and low powers on the two pics.
Yes I am outputing DC.
I was getting around 130amps but the input voltage was dropping below 200vac so I will test again when i get the wire feeder home.
About the wirefeeder - it came from a scrapyard - the motor needed new bearing and all the magnets have detached from the case (they are glued to it). New roler was made, the electronics came from an old welder - needed repairing. (here a pic - it is on my big heavy transformer mig-mag - you can see the cable coming from the left going to the inverter)
Cheers
Dr. H., Thu Feb 05 2009, 09:42PM
Good day guys
Really good article ConKbot and thanks for the explanation. About the welding - I am not a welder - my father is. I was just demonstrating high and low powers on the two pics.
Yes I am outputing DC.
I was getting around 130amps but the input voltage was dropping below 200vac so I will test again when i get the wire feeder home.
About the wirefeeder - it came from a scrapyard - the motor needed new bearing and all the magnets have detached from the case (they are glued to it). New roler was made, the electronics came from an old welder - needed repairing. (here a pic - it is on my big heavy transformer mig-mag - you can see the cable coming from the left going to the inverter)
Cheers
Re: HF Mig-mag welder
Dr. H., Sat Feb 07 2009, 06:34PM
Hi guys
today I got lucky in the scrapyard - I bought a wirefeder for 10$ wheee
The motor requires a new bearing but that is an easy change
Cheers
Dr. H., Sat Feb 07 2009, 06:34PM
Hi guys
today I got lucky in the scrapyard - I bought a wirefeder for 10$ wheee
The motor requires a new bearing but that is an easy change Cheers
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