Sears MIG Welder

Hi Dick...if you are confirmed that all you equipment is in good working order.......then use straight argon...I also have to suggest that metal preparation is very important...lots of old vehicle body parts contained lead....years ago I welded a trunk on a 56 chevy that a buddy of mine was fixing up...terrible results intil I ground away the lead.........so I suggest grinding the metal lightly without thinning the wall thickness to expose pure steel. Try to create yourself a windless environment with shields etc.. to prevent shielding gases from being blown away from the weld.
And another question you had " Is this welder any good, does anyone know who madeit for SEARS?" No...it is NOT a 'good; welder and was made cheap to allow cheap sale...hense ..."you get what you pay for"
Hope I was of some help..... Jim Morris

Can't offer any gas help (stick man), but Century has made all the Sears wire welders I'm aware of. They also made most of the stick welders, with a few older ones being Emersons.
GTO(John)

Using the Argon/CO2 combination for MIG is fine. The most common is 75% Argon and 25% CO2 and called C25. There are quite a few different mixes, some also having O2. I think Jim & Lil are confusing your machine for a TIG since that is the only use I know of for pure argon when welding unless you are running brazing wire in it. As far as the problems with your welds... I would guess the machine first with the little bit of info so far given. Drag a fender down to a welding store and try it out on one of their machines to see if it's the metal or the machine setup or you.

Aren't stainless and aluminum MIG welds done with 100% AR?

Yes, you are so very right. At least I know it's fact for Aluminum. Doh! Stainless likes a mix like 90% helium, 7.5% argon, and 2.5% carbon dioxide for short circuit as far as I am aware. Spray can be something like 1% or 2% oxygen in the argon mixture .

Learn to weld. Thin rusty sheet is hard work, and not somewhere you want to be practising your technique. Find a wheelbarrow full of clean 1/4" scrap and practice welding that first (all dials set right up) until your technique is good. Then start working on turning the dials down and working thinner stuff.
You can book learn this stuff (I'd suggest Gibson's "Practical Wedling", but that's a UK text), but you do need to practice it.
One of my pet hates is domestic MIG sets with pure CO2 from a pub "because it's cheap". You don't say what your gas mix is, but using some real gas that's basically argon with just a few extras in it will give you much better welds. As to the exact mix, then that's less critical - but avoid O2, unless you really are welding stainless.
Chances are that you're running into globular transfer mode, rather than dip transfer. CO2 will do that to you on a small set. Find a book with good pictures, get the set running hot on thick plate until you understand what the different modes feel like, then start working on reducing things to a reasonabe power level, without the quality going off the beam.
-- Die Gotterspammerung - Junkmail of the Gods

Actuallly, he did state that he's using argon C02 mix.
J

Hobart 200 amp welder (miller) with spool gun option is now sold with sears brand now in tool catalog.

Yes Jeremy, Aluminum and stainless ARE done with straight argon gas and so can mild steel..... reason I suggest straight argon is that it gives the weld a smoother finish and does not have the penetration or 'Push" that C15 does. I hold a pressure ticket in using a "Mig root" process. The process was used because the pipe was to be internally coated for acidic sour gas and needed a smooth bead. The process involves taking the pipe bevel and grinding the land off to a sharp point (zero land) then using a 5/32 gap (Frigging wide) and .42 wire and straight argon gas the mig root was put in. The hot pass was also applied using mig process...Then the weld was filled and capped with 7018. We had tried the process with 02, but the push that it gave left too much build up in the inside of the pipe and under xray, the porosity was immense...so going to straight argon .Left the weld lay flat on the inside. Purging the joing on the inside was not cost effective as we were required do do 'Many joints" a day. All pipe joints were done in the flat to about 2 oclock position...somewhat downhand...on a "pipe roller"
No I didn't get mixed up with tig process.....Reason I said straight Argon is that It will allow him to weld on thinner material without the 'push"...try it... regards...Jim

It was probably made by Century but a model number would help.
Does it look like this one only black?
Century isn't considered one of the top brands but I had a Century and had no problems with it whatsoever. The only reason I got rid of it is because I moved up to a 220V Lincoln and couldn't afford to keep both.
What size wire are you using? For body panels I'd recommend .024. The best thing to do is pick up some scrap sheetmetal somewhere and practice quite a bit so you don't have to worry about screwing up the body panels while practicing.
If you're not sure how to set it up try this:
Set the voltage knob to the lowest setting and then while welding turn the wire-speed knob until you find a point where you get the smoothest arc and that classic "frying bacon" sound and it should do a decent job.
Best Regards, Keith Marshall snipped-for-privacy@progressivelogic.com
"I'm not grown up enough to be so old!"

Thank you Jim for the correction and detailing the process. There's always something interesting to learn here. :^)
I'm not sure if I'll get a tank of pure Argon though because the results may not be the same on my "baby mig", SP125. I have trouble enough with C25 making high round beads. If I had one already, I'd love to try it on the thin stuff. It probably will work great for the original poster on auto panels. Maybe when I find room for a Syncrowave...