Amps vs Thickness

[tonyrico]

I'm new and just getting ready to buy my first mig unit. It will be for hobby, fun, some light fab and some farm stuff tractor implements, fence...
My question has to do with machine ratings. The mm180, which I am strongly considering, is rated at 5/16 in a single pass. Now, does that mean I can 5/16is the wall, or can i weld something thicker if I make multiple passes, or if I weld it on both sides?
I don't want to under buy, but this is as far as my budget will allow at this entry point. Down the road I know I may need to upgrade. I see posts that basically say to buy the most you can afford, but application also comes into play. When I'm ready to build dozers out of 2" plate, I know I'll need more umph, but for now I ask for your comments please.

[Black Wolf]

Q1: Yes, you can weld thicker than 5/16" with properly stacked multiple passes.

Q2: Yes, you can very thick items with proper joint preparation, bevelling, back gouging and multi pass welding.

With proper training and understanding of joint preparation and of the welding process, in this case GMAW, one would be amazed by the work a welding machine of this size can do. The weldor makes the welding machine, not the other way around.

What that machine will do for YOU is dependant on your skills & abilities. I do not have a MM180, I have a Lincoln SP-170T that I have on occasion stretched WAY beyond the manufacturers recommendations. How do I do it??? Joint preparation and a solid understanding of welding procedures.

Hope it helps.

Later,
Jason

[tonyrico]

Amps vs Thickness

Jason, thanks.
You replied with what I expected, but I needed some reinforcement from an experienced welder. I consider the MM180 entry level, and seeing it in action it appears to have enough juice to do real welding beyond just hobby stuff. Certainly at some time it won't be enough but until I get into it I just won't know.
Again, thanks

[Black Wolf]

When you're ready for it, and you have gone to the acceptable limits of hard wire GMAW, then you still have flux core self shield FCAW-SS and flux core dual shield FCAW-DS wire to work with. The FCAW process will allow you to stretch your machines capabilities further because of the mechanics of the process. If your machine does not have a setting for FCAW, remember to manually change the polartity.

GMAW=DCEP= DC Electrode Positive or Reverse Polarity.

FCAW= DCEN= DC Electrode Negative or Straight Polarity.

Also to improve your penetraion while welding, use a drag technique, which produces a narrower bead with deeper penetration. The push technique gives you a wider, flatter bead profile with shallower pentration.

Later,
Jason

[Sberry]

When its time for real heavy work this little machine can become a good second unit, these machines are ideal for the light general fab work you are wanting to do. A 180 is worth every penny. Great starter machine. I use a machine in that class as much as a big one in my shop. Got one pretty much dedicated to the vice/workbench, also ust it as a portable in the shop. Wheels easy, got a long cord.

[Black Wolf]

Cary,

Sounds good to me.

[tacmig]

What's enough?

I agree 100% with Black Wolf in that you can (with the proper prep) do work well beyond the MM180's recommendations. I have a MM175 that I have stretched into neighborhoods it was never intended for, but got away with it using tricks of the trade some of which Black Wolf mentioned above. However, you may not want to, may not have time to or perhaps for other reasons spend a great deal of time learning, researching etc. just to get an extra mile out of a smaller machine? Based on what you have said or rather asked, I would recommend that you look at a larger machine i.e. 212 or even the 252. The money you spend now will be more than made up for in the future with increased capabilities! I'll bet there is not one pro-welder on this board such as myself that didn't start with a small machine and later had to up-grade. In addition I'll bet there is an equal amount of week-end fun seekers that purchased a small machine only to up-grade later!

Good Luck

TacMig

[Jolly Roger]

You would lose that bet, lol. I started on an SA 200. I now use a much smaller machine, as in weight anyhow. Actually the only real discernable difference is that it is red and weighs less than half as much. More economical on fuel too. Rated at 210 amps at 100%. Cost a lot less too. I haven't purchased a Mig machine yet for shop work. I have a hang up about single purpose machines, so I got an xmt304 and a suitcase wire feeder. It will run at 160 amps all day and that is a pretty good fire with a mig, but it can go much higher.

My business partner has a weld pak 155 and I am amazed by what I have gotten out of it, but it can't operate at the level I want it to due to duty cycle. We use it for ornamental iron and light repairs like welding fenders back on trailers and such.

I have a weld pak hd that I got specifically for repairing hand rails and burglar bars on site and it does that very well with it's biggest plus being light weight. It really isn't good for much else.

A good welder can do amazing things with a mediocre machine. A great machine cannot help a mediocre welder.

[kiwi]

I am a hobby welder and don't have 1/1000 of the knowledge of the other gentleman on this board, but I would like to make one point. It is true that you can stretch the limits of a machine by understanding the principals, beveling and a myriad of other techniques. I did that for a long time and you can get by, but it is very time consuming. When I went from my Weld Pac to my MM210 it was like night and day. I went from spending a great deal of time preparing my welds and welding a little to less preparation and welding a lot. Remember I am a hobby welder and these guys have a great deal of knowledge, but I love my MM 210 and have never regretted the purchase.
Nick

[Sberry]

The work they can do for the cost is a great value on these 180 class machines, any of these are, the 400 extra for the 210 wouldnt be a deal breaker or give me buyers remorse either.