Going from 120 to 220, real world pentration, general welding q's

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So I had the opportunity to use a Hobart 210, and I also upgraded my garage to put 220 in there to try welding with my first edition Miller Passport. I understand where people say the Passport has a soft arc - I practically jumped every time I squeezed the trigger on the Hobart, the arc went "SNAP" as it connected. It also felt much more powerful. Although the Passport on 220 seemed to weld a LOT better than it did on 110v on my 1/8" scrap. Now here is my question - with my Passport, turned basically all the way up to the max, dragged the puddle, and went real slow, I could see a bit of weld poking through to the other side of the 1/8" metal. It's rated for 3/8" which IMO seems to be a pipe dream. I was hoping to get 1/4" out of it, but with 1/8" it was just barely able to burn through to the other side. 1/8" to 3/16" the max out of a 180 amp (max output single pass real world) mig running 21 volts? Looking at other 180 amp migs on the market, it seems not any are really rated for 1/4".Also next question, here are some images of someone's weld on 3/8" material using a Miller 211. To me, these welds look like they went about 1/16" of an inch into the material. Is this what a proper weld is supposed to look like? According to the review, this is the 211 set to the 3/8" setting on autoset.(Click images for larger version)Now, it just looks to me like that really isn't penetrating into the base metal much at all. Was wondering if folks could post some images/links to what a proper weld penetration bead should look like?The "rule of thumb" I've read about is 1 amp per 0.001". So 120 amp output would weld .120 material (1/8" +/-). A 210 amp machine could weld 0.210", not anywhere near 3/8" like the 211 claims.
Reply:What you describe when welding your 1/8" material is called burn through, not penetration.Complete joint penetration can only be done with a groove type joint, such as in a butt weld, with preferrably having some type of bevel. The pic with the markings is showing the fusion area of the welds that were done. Fusion (mixing) of the parent metal and filler metal is what you should be aiming for when doing a weld and your not going to get the wire piercing through the plate.
Reply:A couple of things you have to understand about penetration. 1st  you really aren't trying to punch straight thru the base material to the other side on average.  If you tried to do that on a tight fit but joint you wouldn't be able to get a decent single pass weld.  You'd need to bevel and properly prep that joint to do a single pass weld on 3/8" no matter what process you were using, unless you had a super large machine.  A fillet weld is a bit different. Unless the specs call for a full penetration weld, you don't bevel the joint usually.Also different joints "behave" differently as far as penetration is concerned. A fillet joint gets it's strength from the large surface area the weld bead contacts on both legs, as well as the reinforcement between the two. A but joint gets it's strength almost entirely from the surface contact area of the weld.In the example shown at the top, the one on the left shows plenty of penetration into the base material on the one side. The second side with less penetration looks like the leg is too small. It certainly doesn't look to be 3/8" comparing it to the base material. Looks like the person who did the weld favored the "better" side. The one on the right looks to be a bit lacking to me. Without any other information it's tough to draw any real conclusions. Honestly I'm not terribly impressed by those examples, especially the lower one which would fail visual inspection simply on the fact the legs are too short from what little I can see.As far as the  " 1 amp per .001" rule" that doesn't really apply across the board on average. It works well with tig under say 200 amps for steel. You can weld way more than 1/8" using 125 amps with a stick welder. In fact most guys would have real issues welding 1/8" thick steel at 125 amps with 7018, let alone running the same bead with say 6010 at the same amps. The amp suggestion doesn't even work if you use the .001 rule and apply it to the rod on stick. 125 amps works for 1/8" 7018 rod, but it's still way hot for 1/8" 6010. Mig is a constant voltage process, even though migs are often rated in "amps". Amperage changes based on wire speed and stickout given the same voltage setting. Then you get into things like FC wire vs the different types of shielding gasses. 100% CO2 will give you a "hotter" weld than say 75/25 will at the same machine settings. If you look at most of the charts, FC wire will usually be listed as giving the maximum thickness. Then there's things like push vs pull, and  any welding motions like circles or a Z shape that changes how long you stay in one location and in the puddle..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Thanks guys. I took a MIG class but it wasn't very good, so I am resigned to trying to learn online. I did learn a bit, but it was just a short 2 hour course. Unfortunately nothing in the area is offered as far as 3-4 week classes go.Last edited by wheelsup; 02-23-2013 at 01:14 AM.
Reply:Adding your location to your User CP at the top left wouldn't hurt. You might find someone here in your area than can suggest a course or who might be willing to help you learn..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:OK thanks, I added my locationMiller Passport