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ARC WELDER MACHINE - CONCEPTUAL

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StormInABottle

Mon Jan 28 2013, 09:05AM

Registered Member #9252 Joined: Fri Jan 04 2013, 06:27AM
Location: Andromeda
Posts: 253

AwesomeMatt wrote ...

wrote ...

And that is a really nice tutorial on how you do what he did.

It covers everything.

Why thank you for the kind words. Some day I will finish the actual project videos that were supposed to come after them :)

You're the one who created those videos.?

JESUS i find the creators of all the awesome videos on youtube on these forums
Thank you for being kind enough to release those tuts

AwesomeMatt

Mon Jan 28 2013, 11:53AM

Registered Member #4454 Joined: Sun Feb 26 2012, 12:47AM
Location: Western Canada
Posts: 74

Arcingnoob wrote ...
You're the one who created those videos.? Thank you for being kind enough to release those tuts

I am, you're welcome. No one learns in a vacuum; very little of what I showed was anything I discovered. After a few years of mooching off the global DIY community without making much new, I thought I could at least contribute back by coalescing all the advice I'd gleaned into some tutorials. I'm not smart enough or knowledgeable enough to push any boundaries, but I think I'm okay at cutting to the basics and teaching people. This also eases the burden of those I learned from so they can stop iterating the same low level things over and over to people like me.

Steve Conner wrote ...
Stick welding electrodes are designed for use with DC (AFAIK)

Nope, almost all sticks are designed for both. For decades they only had AC anyway.

Most of the energy (80%?) ends up on the positive side of the arc, from the impact of the electrons. This is important in TIG welding because the tungsten electrode is non-consumable (well, slowly) and you don't want any heat there, you want it on the weld itself and if you want to add material you have a separate filler rod. In stick (aka "Arc") welding, it doesn't matter much if you heat up the electrode 'cause it's consumable and being shoved into the weld anyway.

Old stick welders are called "Buzzboxes" and they're just plain 60hz 20v from a stepdown. My little one has an on/off switch and that's it, no current control, no multiple taps, no DC, no foot pedal, nadda.

DC does make a weld nicer in most cases because the arc isn't being extinguished 120 times a second. It's smoother and easier and less angry. It's a cute little upgrade to an arc welder. A big inductor is another nice upgrade, helps not extinguish the arc if your distance wavers.

Aluminum needs (doesn't actually need, but is hard to weld without) AC because it builds up some gunk which is helpfully blown off by the polarity reversing. Something around a 20% reversal from normal (electrode positive) is usually sufficient... but you can give it 50/50 plain 60z. Less than optimum but probably not noticeable to an amateur.

There's not really any point in building a DIY switchmode inverter stick welder. If you're making an inverter welder, go straight to TIG, it's almost universally superior.

Anyway, not really what the thread starter wanted to talk about, so, I'll hush up and let him document his build.

Newton Brawn

Wed Jan 30 2013, 02:31AM

Registered Member #3343 Joined: Thu Oct 21 2010, 04:06PM
Location: Toronto
Posts: 311

AwesomeMatt,

I Agree with you.

I have used stick weld in the range og 60~240A ac and sometimes dc. One machine (Buzzbox transformer) deliver 80V ac 60Hz to a iron core inductor, with several taps. I select the taps in such way that the series inductor control the welding current.

The other, also a transformer buzzbox, have a iron core shunt between the primary and secondary. A long threaed rod contror the position of the magnetic shunt in such way that the output current may be set between 50~250 A

Both buzzbox are heavy, in the range of 60~80kg. Heavy stuff, dificult for me carry out of the shop.
My dc equipment have a full bridge diodes, 180A with 2 computer fans. It is connected to the buzzbox when I need to make a dc welding.

However, most of time I use ac weld, and not use to much the rectifier box. It is a personal preference.

When I need weld aluminun I go to a nearby shop and use the TIG that is there. ( and next week they call me to fix some electrical stuff...)

Long time ago, I have made a small buzzbox using 2 cores of two MOT.
To open the MOT iron cores I use a hand saw, openning a 2mm dip slot in the weld that joint the "I" and "E" cores.
The secret is open this slot litle bit away from'E' "I" junction, so the "E" core is not affected by the cutting, only the "I'.
After the coils are placed inside the two "E" , the core is closed and the "Es" are assembled in reverse, and the "I" cores are displaced to the recicle.
Due the distance between primary and secondary coils that is about 10mm (65mm electrical) the dispersion reactance helps to limit the secondary current. Secondary current 40~120A. Easy to carry out the home. I do not have this buzzbox animore...Maybe I should construct it again.

Newton Brawn

Thu Jan 31 2013, 10:59PM

Registered Member #3343 Joined: Thu Oct 21 2010, 04:06PM
Location: Toronto
Posts: 311

Hi !

Returning to the conceptual, here is the inverter.
To be honest I have copy and paste it from internet. the site is

I hope someone with experience in IGBT tell me the required protection for IGBTs

Newton Brawn

Fri Feb 01 2013, 03:03AM

Registered Member #3343 Joined: Thu Oct 21 2010, 04:06PM
Location: Toronto
Posts: 311

Here a better diagram:

1359687745 3343 FT149248 Inverter Rev2 Jpg

Steve Conner

Fri Feb 01 2013, 08:22AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Looks fine. It is similar to some schematics I saw for an Esab inverter stick welder. It actually used two circuits like that with the outputs paralleled, for more current.

Modern fast IGBTs don't need the RC snubbers though. (they have a "square SOA"- they can switch just as much current as they can carry)

Why did you use two different diodes for the output rectifier? The requirements are just about the same for both of them, and most of the fast welding rectifiers you can buy come as dual modules anyway.

Newton Brawn

Sun Feb 03 2013, 01:24AM

Registered Member #3343 Joined: Thu Oct 21 2010, 04:06PM
Location: Toronto
Posts: 311

Hi Steve:

Do you have the part number of a IGBT that have a "square SOA"- they can switch just as much current as they can carry ?

I specyfy two different diodes in the secondary output rectifier just because this was especified in the inverter diagram.
I agree that just one kind of rectifier is reqired, in the case a dual STTH200 - 600Vpiv
Follwing the original concept, two dual diodes are rquired for lower temperature rise.

By the way, can you send me the ESAB inverter schematic ?

Regards

Steve Conner

Sun Feb 03 2013, 08:59AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

One example IGBT would be the HGTG30N60A4D from Fairchild. It was marketed as an upgrade for designs that used IRFP460 MOSFETs. As an experiment, I substituted one into a 100kHz boost PFC that previously used an IRFP460 with no snubbing or energy recovery circuits. It worked fine and even without optimising the gate drive, performance was slightly better than with the MOSFET.

I'll see if I can dig those schematics up.

Ash Small

Sun Feb 03 2013, 02:16PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Is this of any use?
]an-1045b.pdf[/file]

Billybobjoe

Mon Feb 04 2013, 01:12AM

Registered Member #396 Joined: Wed Apr 19 2006, 12:55AM
Location: Pittsburgh, PA
Posts: 176

Newton Brawn wrote ...

Here a better diagram:

Maybe I'm missing something obvious here, but how does T1 ever seen AC? This doesn't look like a typical half bridge driver

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