Question on MIG welder specs

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So I am getting ready to buy a welding machine and the choices are the Millermatic 252 the 212 and the Multimatic.I am new to MIG welding so dont know much about it to start off. My main question is the capability to weld certain metal thickness in one pass. According to the website the 252 can weld up to 1/2 inch and the 212 up to 3/8. Sooo what do they mean? like you can get to pieces of 1/2 inch plate butt it up against each other and weld it up and it will hold to the same 1/2 inch strength? other then that why is the 252 better then the 212?These kind of ratings are new to me I only went to school for pipe welding and we only worked with TIG and stick and was beveled and had a gap, so pretty much had one amperage for the root, another for the hot pass then finish it out. So by my logic couldnt you just get the 212 or even the multimatic and weld any thickness steel and just bevel  and gap it?
Reply:You need at least a certain minimum amount of power to make sure you get decent penetration into the base material. That's why you can't simply take a small 110v machine and get decent welds on say 1" even if you do bevel the material. Once you get up into the amp/ volt range of 200+ amp machines, usually this isn't as big an issue. Bigger machines have a couple of advantages. One they allow you to run larger wires and lay down more material at once. Yes you can weld say 1/2" fillet welds, by running 3 beads to get your 1/2 legs, but that takes time. Go with a larger machine and larger wire, and you can do that weld in one pass in the same amount of time it would take to do one of the 3 passes. Also bigger machines have higher duty cycle ratings. The MM211 and the MM212 are both 200 amp machines and rated at 3/8", but the larger MM212 will has a much higher duty cycle. Try and run the MM252 at the max of the MM212, and you can keep welding and welding, where with the smaller machine, you'll have to stop and let the machine cool. The MM252 also has some added features for use with a spoolgun that the smaller MM212 lacks.You almost never can simply but two pieces of 1/2 together and get a decent joint. Usually you have to do some sort of prep, gap and or bevel to get satisfactory results. Fillet welds however can easily be done in one pass because you aren't trying to burn thru all that material.A better idea just what you want to do would help narrow the list down a bit. The MM212 would give you a solid inexpensive light shop machine for mig. The MM252 would give you more options as a heavier duty shop machine with some advanced spoolgun capabilities. It's probably a better choice for a shop that does a lot of medium to heavy mig full time. The Multimatic would give you most of the features of the larger industrial XMT 304's, but in a more compact package, with a built in feeder. A good choice for some one doing a lot of mobile work, or a small shop that needs to do mig, tig and stick from time to time, but not something that gets heavily used day in and out..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:Very informative and you left no question unanswered. Thank you very much DSW. What I want to do is very complicated. I am about to start a career in welding, start my new job tomorrow.I would like to start off with some personal projects such as BBQ pit, Smoker and eventually turn my trailer into a mobile Smoker. After that take on some side work for friends and eventually would like to make some guard rails or fences on the side. The end game would be to some day be self employed.
Reply:I've owned both the 212 and the 252.  The 212 and 252 can use the same spoolgun, although Miller markets a more expensive model towards the 252.  I've welded 1/2 with the 212, but you have to make more than one pass.  You say you are new to MIG.  The 212 has Autoset, which some few as a gimmick, but for just starting out it can really help get you in the ball park.All of the accessories you get with the two machines are exactly the same.The 252 has more setup options.  You can set pre-flow, post-flow, run-in and burn-back.  You can also set up some spot welding timers.  The 252 will remember the last used settings for the spoolgun.Both machines have "gun on demand" which means you can have the MIG gun and the spoolgun always hooked up and the machine powers up whichever gun that you pull the trigger on.It sounds to me like the 212 will do what you want.  I paid about $1700 for my 212 and sold it today for $1300.  That worked out to $200 a year and I used it for several projects.  I bought the 252 because I wanted a larger machine and I found a decent deal.  I do like the extra options, like pre-flow and run-in.
Reply:Originally Posted by pokerguyMy main question is the capability to weld certain metal thickness in one pass. According to the website the 252 can weld up to 1/2 inch and the 212 up to 3/8. Sooo what do they mean? like you can get to pieces of 1/2 inch plate butt it up against each other and weld it up and it will hold to the same 1/2 inch strength? other then that why is the 252 better then the 212?
Reply:I'm a beginner when it comes to Mig. I bought the MM252, and have absolutely no regrets. From a beginners standpoint, I could never understand the point of "autoset". Since I like "real" numbers for learning purposes. The 252 comes with a chart for setting those real numbers anyway.But I'm not the expert here, so don't take my advice for Gospel truth. I just like this 252.Last edited by Gobysky; 07-10-2012 at 07:34 AM.Reason: wording
Reply:Get as big a machine as you can afford. Once you start and your experience grows so does the thickness of the metal you will encounter. My first machine was a MM185, then a MM200. Now I am up to an XMT304. I think if you bought the 252, you can't go wrong, and they hold value well.
Reply:If you like digital meters the 252 has them. You can weld non stop with this machine for what you want to do. I don't think duty cycle will be a issue with either   As WALKER said about getting the biggest you can afford. Both will do what you want.   When it comes to welding thick metals in one pass it depends. Sometimes you may one pass it and then run another half into it and below it. Then run half into it and above it. It all depends on the project . Yes one pass may work but 3 smaller will do a better job.
Reply:well seems like the Millermatic 252 is the clear winner. As far as me starting out in MIG and not being too experienced not too worried about that just found out my schedule today, going to be working 7-10's so I guess im going to get experienced real quick. I appreciate all the input from everyone and now feel very confident in buying the 252. Im sure it wont be the last machine I'll be buying but feel that it will meet my needs for the next couple of years.