January 2, 2005

11:50 AM

Attention handypersons: I have this idea that simple MIG welding is the sort of thing I'll be able to teach myself, without taking a class or otherwise receiving instruction beyond what I've found on the internets. Is this hubris that will end in missing digits, seared retinas and a Darwin Award? (More self-doubt inside.)
posted by psychoticreaction to (16 comments total)

Here's what I wanna do. I wanna weld threaded rods, vertically, to an exposed girder in gf's futuristic loft as part of a futuristic shelving unit. So I ask all amateur and professional handypersons, is MIG welding enough of an intuitive undertaking that a sober and mechanically-inclined person like myself would be able to pull this off? Or is there a serious risk of harming myself, or having a formidable collection of bath products plunge to the floor as a result of incompetently performed welds?
posted by psychoticreaction at 12:00 PM on January 2, 2005

You didn't say if you had any experience mig welding. Are you going to buy a cheap mig welder just for this project? Welding requires that both pieces of metal be partially melted (at least under the weld) and it will be hard to get penetration on the girder without melting through the rod. I would suggest buying some hangers made to attach to girders (I-beam is what I suppose you have). Mcmaster-Carr has some pics in their catalog (half way down page 1363 of their catalog are some for attaching threaded rod to I-beams).
posted by 445supermag at 12:20 PM on January 2, 2005

I would say that yes, you should be able to undertake this project on a self-taught basis.

Are you thinking of purchasing or renting a MIG welder for this project or do you have access to one already?

You will want to practice using scrap metal in order to get a feel for the machine that you are using.

The key to successful MIG welding is penetration. Have you done much soldering (of wire/electronics) in the past? The equivalent of a "cold solder joint" exists in MIG welding for much the same reason that it does in soldering - not enough heat on one or both of the surfaces being welded.

You should be able to pick up a textbook from your local library that can help you with techniques and show you pictures of what your welds should look like.

There really isn't that much risk of bodily harm when MIG welding. You will get "arc flash" if you don't wear a face shield (super painful - you'll wake up at 2 am feeling like your eyes are full of sand). It is possible to give yourself a sunburn if you aren't wearing long sleeves/buttoned up shirt. The metal is, of course, quite hot, but after burning yourself a few times you'll learn to be suspicious of any piece of metal that's anywhere near a welder.

Make sure you have a good (charged) fire extinguisher nearby, and try to remove anything that's super flammable (towels, toilet paper, etc.) from the area that you're working in. MIG welding does tend to "spatter" a bit, shooting out tiny hot balls of steel. You will need to ensure that any spatter isn't going to damage the fixtures/walls/flooring.

I'd be happy to answer any more specific questions.

(not a professional welder, but have done quite a bit of welding and worked in a steel fabrication shop for a few years)
posted by davey_darling at 12:27 PM on January 2, 2005

mig welding at the very least requires a mig welder which you'll either have to buy or borrow. If you borrow it, you can ask the person who has it if your project is manageable. If you buy one, I have to agree with 445supermag that it seems like overkill for this project. We used to have similar shelves at the place I used to work, and they were attached through holes drilled into the I-beams with fancy washers on both ends, not welded. This had the added benefit of making the shelves a bit more portable.

However, to answer your question, mig welding is not at all hard, but it's also not as simple as just zap-and-go. You'll need good eye protection, and eye protection that is good enough for mig welding has the added feature of being close to impossible to see through. To do this sort of welding well, you have to have a bit of a feel for how the weld is going to go before the mask goes down, at least in my experience. Also, since it's a really sparky electrical thing you're doing, keeping an even hand [especially if you are someplace like on top of a ladder, remember, mig welders are heavy] requires a bit of practice, and you have to really watch out that sparks don't go places that they will smolder and/or catch fire. If you really want to do this, you probably can, depending on your ability to follow instructions and use tools, etc, but at least read this page of tips for beginner mig welding to know what you're up against.
posted by jessamyn at 12:33 PM on January 2, 2005

Nah, just buy a welder and go to town! Don't bother with instructions or manuals....just go for it!

In all seriousness, welding is certainly something you can teach yourself. ( I managed it anyway....and haven't electrocuted myself or burned down the house...yet.) But it will take some effort and time on your part. I'd recommend obtaining a selection of books on the subject and actually take enough time with them so that you understand the theory behind melting two pieces of metal together with an electric arc. Then buy your welder and practice with it until you can make decent welds.

One note of caution though: the project you're proposing isn't exactly "basic." Welding overhead is a little tricky. Additionally, butt welding four (or more?) threaded rods to an overhead beam and having them end up square sounds like a real pain in the ass. (Not to mention that fact that you won't end up with a whole lot of welded joint holding this load bearing structure.) Have you considered building rectangular brackets out of angle iron? Then you can drill holes on one of the long sides to accept your threaded rod with a nut on the other side.....then just fillet weld the other long side of the bracket to the beam. If you do this you'll have a stronger joint to the beam, an easier weld to make, and it'll be a LOT easier to ensure that your threaded rods end up square to each other when your done.

You can certainly do this project, but don't expect to buy a welder in the morning and be welding up those rods in the afternoon. Anyway, best of luck.
posted by FredFeral at 12:35 PM on January 2, 2005

I should add that welding or drilling or otherwise weakening or making a point of strain concentration on the bottom (or top) flange of an I-beam is a very bad idea. If you are set on welding, bend the threaded rod so it lays against the center (vertical, inner web) of the I-beam and just droops over the lower flange. Then weld to the vertical web (this will give you a longer (and stronger weld).
posted by 445supermag at 12:36 PM on January 2, 2005

445supermag: I-Beam Swivel and Pivot Clamps, veery cool. Thanks. Had never seen these, didn't know they existed. Really, this is a much more elegant solution to my shelving situation ... but ... must learn to weld ...

Nope, never welded before, just looking for an excuse to learn. But i plan on doing more of it in the future, making rolling carts to move my precious lighting gear around, maybe graduating to the creation of giant flamethrowing robots ala these guys, you know, usual stuff like that. Much experience in electronics soldering, and (correct me if i'm wrong) i have a feeling that the principles of soldering and welding are similar.

I would likely buy my own inexpensive welder. It seems as though a 110v unit would be sufficient, no? And would I need a wire feed unit - they seem to be prohibitively costly.
posted by psychoticreaction at 12:57 PM on January 2, 2005

I've recently been getting into auto-body restoration, and a friend of mine works at a garage and has ready access to all sorts of fun things.

I went over to the garage a few months ago to help him install a new engine (a Chevy 350 into a Pinto -- don't ask!), and asked if he could show me the basics of MIG welding.

In a nutshell: it's a LOT harder than it looks. The biggest problem is that you can't see what you're doing.

The second, and only slightly smaller problem, is that the welding contact gets EXTREMELY HOT. So hot, in fact, that it'll usually burn right through sheet metal in a matter of seconds.

The third problem is that you can't just draw a bead along an edge. You weld a spot, then weld another spot further away, then go back and weld another spot near the first, and back and forth until you've got a consistent weld. My mistake was thinking I could just weld a straight line. It doesn't work like that.

I have the utmost respect for people who know how to do this well. I imagine there's no substitute for practice; providing you follow safety procedures, I say have at it!
posted by Civil_Disobedient at 1:11 PM on January 2, 2005

Civil_Disobedient: The spot welding technique you described is true for thinner sheetmetal (i.e. body metal). It is done this way because the heat generated by laying a continuous bead would warp the metal beyond recognition - requiring significant filler/bashing to get it back in to shape. By welding small areas and moving away, you give the metal a chance to cool down.

psychoticreaction: re. welding vs. soldering: the technique is similar, but remember with welding you are actually fusing the metals together as opposed to using a dissimilar metal to stick them to each other. You will be well served with the basics of soldering such as directing more heat towards the thicker piece and knowing what good "flow" looks like.
posted by davey_darling at 1:59 PM on January 2, 2005

Having someone actually show you how to do it would probably get you there a lot faster than teaching yourself from books. It can be hard to know exactly what to look for - as davey darling says - in terms of good flow, and some of the subtleties of good technique. It's not that it's that hard, but it's definitely something that I felt more comfortable having an experienced guide to assist me with...
posted by judith at 3:01 PM on January 2, 2005

P-reaction,
all migs are wire feed, I think you can get a cheap (century) for $299. Not really a mig (metal inert gas) as sold (they come with flux core wire that doesn't require gas), they do come with a regulator so you can use gas (75% argon, 25% CO2). I've done a lot of MIG welding (8 Hrs a day production welding, custom fabrication, Street rod/ custom car) but I still have a hard time getting a decent weld out of my flux core welder. If something really has to hold, I use my old "buzz box" stick welder and 7018 rods. I recently went back to my old work place and borrowed their welder for a particularly difficult weld. They had bought a new Miller MIG since I had left, and welding with it was amazingly easier (easier than good grammar and style anyway). If you want to do SLR sized stuff, you should have a 220V welder. While most people don't have 220 or 208 V three-phase power service, they do have 220V single phase for electric stoves and clothes dryers. I made a long extension cord that goes from my dryer plug to my welder. I would buy a used Miller professional welder rather than a new cheap mig. If you have the money and think you will get more involved with metal fabrication and welding, you may want to buy a "power unit" that can power several different things (MIG wire feed unit, TIG torch, stick) and add capabilities as you need/can afford them.
posted by 445supermag at 3:08 PM on January 2, 2005

I have taken a couple of welding classes at my local high school continuing ed. place so I'm definitely not an expert, but I have had a chance to play with a bunch of welding equipment of various types.

Spot welding small/thin stuff with a MIG welder seemed more like using a glue gun than anything else. Once it is et up right getting it to stick two pieces of metal together is easy, well within the boundaries of "teach yourself."

BUT there is quite a lot more to welding than that, and you want to proceed with caution for anything load bearing -- and, if I understand what you want to do, you are trying to attach something that will take the weight of books to existing structural ironwork... I don't suppose you will weaken the existing girder (though it may be a possibility), but getting the rods properly attached will be more of a challenge, especially if you care about neatness, and it may not be obvious whether or not you have succeeded until the books come crashing down.

It sounds like it would be easier and cheaper to just drill holes (also potentially weakening the girder if you aren't careful) and then bolt your threaded rods in place. Welding is fun though...
posted by Quinbus Flestrin at 3:20 PM on January 2, 2005

I really think welding to the girder is a bad idea. The heat is going to destroy its strength and that could result in Really Bad Things.

I should think a couple of well-placed holes will weaken the girder less, and the girder clamps will leave the girder entirely unaffected.

If you're gung-ho on a metal project, though, why not design your own clamping system? Best of both worlds that way.
posted by five fresh fish at 6:18 PM on January 2, 2005

Perhaps an easier answer would be to drill and tap a hole, since this is threaded rod? It would be easy to make square.
posted by jewzilla at 7:42 PM on January 2, 2005

Clamp, don't drill.
posted by aramaic at 8:43 AM on January 3, 2005

I like the clamp idea. They have been ordered. Still gonna weld together an unholy army of the night, though. Thanks yaw!
posted by psychoticreaction at 11:18 AM on January 3, 2005