Inductor value for a mig welder

I bought a cheap harbor freight mig to weld thin gauge metal, It splatters something terrible so i opened the case to find only a transformer and a few diodes, I
hope to add a inductor to help stabilize the arc. The welder is 70-90 amp output, I have a high current air core choke thats heavy enough but i need to add a core of some type to raise the inductance. It has a 2" round I.D. I need a sugguestion of a type of core to add to it & maybe a value in mh ?
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snipped-for-privacy@conninc.com wrote:

You are REALLY wrong about what's happening. It isn't the transformer or the arc characteristic that's giving you crummy-looking welds, it's the fluxcore wire, which is the nature of the beast. Live with it until you can afford a real MIG welder which will let you run a gas shield, then you can easily run gorg-ass beads all day long.
And by the way when you go to sell your HF "MIG" welder, *please* don't ask more than $45 or so, that's all they go for used. They are essentially throwaway units. Think of it like you paid $139 (or whatever) for a lesson in how to not buy a welder, and you got a $45 welder thrown in with the deal.
GWE
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I wonder why they call it MIG. MIG stands for Metal Inert Gas. But there is no gas capability in that "MIG".
i
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Good question, ive noticed the cheap migs that also have gas hookup are called Dual Mig mine just says mig & should say AC flux wire welder, without a inductor it acts like AC anyway.
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Ignoramus29795 wrote:

You're right, Igor, but MIG has long since lost its narrow meaning, and now is often generalized to mean anything that includes a wirefeed. If you want narrow meanings then use FCAW (like the HF machine) or SMAW (what you think of as MIG).
GWE
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SMAW is arc welding, the correct term for wire feed is GMAW, more generic than MIG or MAG.
Grant Erwin wrote:

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On Tue, 03 Jan 2006 16:48:10 GMT, Ignoramus29795
Depending on who "they" are, they don't. It's MAGS unless you're using argon, and only in that case is it MIG.
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replying to Andy Dingley, Kenneth E. Ghost wrote: Easy to add argon to the HF 90 amp. I am in the process as I speak. Fun too, learning a lot. Added a bridge R , 160,000 mf cap total, torrid coil, single 20 amp outlet in front panel/power on indicator , heavy power cord and very heavy work clamp. works like a dream and, its 120 v 20 amp rated, I can take it anywhere. Gas hookup will be done this week.
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The others have told you about the real problem but if you want to see if it helps put the inductor into the ouput lead. I assume it will handle the current. Try the welder and see if it is any better. If you want more inductance, try putting a mild steel core into the center of the coil and see it that helps any. If you want more try making a loop of mild steel, however, you will have to leave an air gap or the core will staturate rendering it useless. As for value, don't know, all you have to do is shift the voltage/current phase a few degrees such that the arc and voltage don't go to zero together. If you have long secondary leads there supposedly is enough inductance in them to do the job. You can add the inductor outside the box so it will be easy to fool with. If it really helps then you can worry about putting it inside. billh

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billh wrote:

thats ALL thats in there?
No caps either and no choke?
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Yep thats all, its a ( Chicigo Easy Mig 100 ) sold by harbor freight and assembled in Italy. It does have two small caps & a resistor feeding the unregulated wire feed motor.
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snipped-for-privacy@conninc.com wrote:

several large electrolytic caps rates at at least 200v should help smooth that out just keep hooking them in parralell
as for those who pointed out that a choke is for CC and caps are for CV essentially half waves leave you welding with AC and even a kick in the nuts would work better than that
BTW instead of getting a Big massive iron cored toroidal inductor the caps are way lighter.
I would however like to say that i agree with whoever said this was an example of what not to buy in a welder. its not a product of appropriate quality and the caps probably saved them 1 or 2 dollars in expense to witre it up
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wrote:

Don't want to get into a semantics argument but welding with half-waves is not welding with AC. The current/voltage may go to zero which isn't ideal but the opposite polarity does not exist. A half or full-wave rectified waveform with the peaks in the positive direction has a positive DC component to it. If it is reversed, then it has a negative component, but not AC. billh
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<Snip>

Point taken it is still DC but it is not the Constand Voltage power supply that the mig family (GMAW and FCAW) are supposed to use.
You agree with the overall message though?
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Yes, I agree and am somewhat amazed that a box with so little in it functions as a CV supply at all. I don't really know all that much about MIG but I was under the impression that the wire feed rate determined the voltage across the arc. It is hard to see how this could be reasonable well maintained with a supply that is so crude although the rather rapid 60hz (or is it 120hz) pulses from the supply probably wouldn't be seen given the relatively slow burning of the wire. The box is operating on the unregulated average dc voltage. Capacitors certainly would be a good place to start and I imagine they are quite large in value. Whether or not they have a large beneficial effect might be questionable given the crudeness of the rest of the system. billh
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i'd like to see what the bead would look like compared to a less cheap machine for the same setings angle and travel speed
I bet the bead produced wouldnt be considered acceptable to many

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Just be sure that your choke is rated for 70-90 A. Back EMF should make your choke run hot so you may need to put a fan on it too.
billh wrote:

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Ya know, aren't MIG welders supposed to be CV welders? That means a bank of capacirors, NOT a big inductor. A big inductor makes a CC welder ..
GWE
Robert Ball wrote:

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Looks like we jumped in too quick, you are correct about constant voltage (CV) vs constant current (CC).
Grant Erwin wrote:

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Tend to agree. billh

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