Monday, June 10, 2013

Welding Question

This is a slightly embarrassing question to ask, because my father made his living as a welder most of the time that I was growing up -- but I never actually learned much about it from him.  (It wasn't in a book from the library, so I wasn't much interested.)  When welding two pieces of steel or aluminum together in a butt weld, what additional thickness can one expect the weld to add?  Say you welded two pieces together that were 12" long each; how long would the final product be?  My recollection from looking at welds, and from reading the Wikipedia page, suggests that welding might add 1/8" of an inch to the length.


  1. I'm not an expert, but that sounds about right.

    I think it will vary a bit by the thickness of the material (thicker material needing more gap to let you weld it properly).

    If it's quite thin stock, you might not need any gap at all, and be able to get enough weld on a straight butt with the pieces touching. (Which assumes you don't need both of the "flat" edges to be perfectly flat.)

  2. Clayton,
    The only reason the total length would be more than the sum of the parts is because you left a gap between the pieces before you started welding. Actually, this is the usual way of doing things if your material is more than say, 1/8" thick. However, it doesn't really HAVE to be that way, nor is it proportional to the thickness. You'll usually grind a bevel into one or both of the parent pieces to allow the weld to be laid down in layers or "passes".

    Dunno what process you're planning on using, but if you're going to be doing the welding yourself, get the equipment and a bit of starter advice (books, Internet forums, or an experienced person), then do some welding. Like any other skill, you must spend some time actually doing it, but it's not that difficult.

  3. If done with the proper chamfering there should be 0 extra length.
    Let the welder know in advance if you need a exact dimension.
    If you cannot chamfer the the welded area then you might be able to tack weld the pieces tight together at your desired length and then try to weld them.
    Without actually seeing the pieces that need to be welded, this advice should be taken with a grain of salt.
    Again, the big thing is to talk to the person doing the welding.

  4. That was the case with my dad, his trade of carpentry, and me. I learned masonry because he needed someone to help, but the carpentry he could do by himself. As a consequence, I know next to nothing about carpentry except I know next to nothing about carpentry.