fillet welds with a stick

Discussion in '<a href=' started by BRIAN GALLO, Mar 9, 2002.


    BRIAN GALLO LawnSite Senior Member
    Messages: 282

    Hey stick welder's, I have a question. I can weld flat, butt or bevel welds with much success, but I can't get a good fillet weld to save my life! I just can't seem to get the angle or penetration right no matter how much I practice. any pointers???? :rolleyes:
  2. 75

    75 LawnSite Senior Member
    Messages: 992

    First off, I'm going to assume we're talking about fillet welds in the flat position.

    Actual technique varies a bit depending on the thickness of material and size of weld desired, but the basics are similar: Rod angle should be about as shown in the photo, to keep the two "legs" of the fillet weld the same length. Also have the rod angled about 45 degrees or so in the direction of travel - in this case I am welding from left to right:

    fillet weld demo 1.jpg
  3. 75

    75 LawnSite Senior Member
    Messages: 992

    On welds like this I generally don't weave, or weave very little. In the one I did here as a "demo" I didn't weave at all, just ran a straight stringer bead. Important thing with fillet welds is to keep both legs the same length - in a case where two different thicknesses of material are being joined you may have to alter the rod angle slightly to keep a bit more heat on the thicker piece.

    When running the bead, remember to keep the travel speed constant. Speeding up/slowing down will change the size of the weld bead.

    fillet weld demo 2.jpg
  4. 75

    75 LawnSite Senior Member
    Messages: 992

    If a larger weld is required, use multiple passes to achieve this. I did three passes for the "demo" weld, the first pass I did is called the "root" pass. Here, the second pass is laid down in the "corner" where the bottom leg of the root pass meets the material:

    fillet weld demo 3.jpg
  5. 75

    75 LawnSite Senior Member
    Messages: 992

    Third pass goes on up top, and brings the weld back to having equal length legs. For a larger weld, simply continue adding pases in a similar pattern, it will likely be necessary to put 3 more passes on at this stage to keep the fillet legs equal: Bottom, middle, top.

    fillet weld demo 4.jpg
  6. 75

    75 LawnSite Senior Member
    Messages: 992

    A common mistake is trying to lay down a large bead in a single pass. This results in "overlap" - along the bottom outside corner of the weld bead it hasn't fused to the base metal. So the portion of the weld that's actually doing something is about the same size as the root pass in the earlier pic.

    Hopefully that can be of some help, now if it's fillet welds in the vertical position that can be a little trickier.....................

    fillet weld demo 5.jpg
  7. 75

    75 LawnSite Senior Member
    Messages: 992

    .........................but not impossible. Rod angle for vertical up is a little different, as shown here you still want to keep the leg lengths of the fillet equal but instead of being angled in the direction of travel, you want the rod pretty much straight on to the workpiece.

    fillet weld demo vertical up 1.jpg
  8. 75

    75 LawnSite Senior Member
    Messages: 992

    For vertical up welds, typically you want to use a heat setting in the lower portion of the heat range for the electrode you're using.

    Example: for 1/8" rod, the "rule of thumb" of 1 amp per thousandth of an inch of electrode diameter equals 125 amps. For vertical up, try it at 120 and see how it works.

    It should be possible to run a stringer bead straight up without having to stop/start or weave it on the root pass, as was done here:

    fillet weld demo vertical up 2.jpg
  9. 75

    75 LawnSite Senior Member
    Messages: 992

    On subsequent passes, for vertical up I like to weave 'em but you can also run stringer beads in the same manner as the flat fillet weld.

    To weave, starting at the bottom you want to get a "shelf" started and work your way up, weaving from side to side and pausing momentarily each time you change direction to fill in any undercut along the edge of the weld. Key here is to be smooth and steady, and avoid "whipping" the rod from side to side real fast. In this pic I have only welded partway up on the second pass so you can get an idea of the "shelf".

    And it took a long time for my vertical up to get to this stage so don't get discouraged! Vertical up is challenging, so just get some scraps like the ones shown in the pics and practice away!

    FWIW, all the "demo" welds were done using 6013 rod with an AC machine, and I used 3/32" diameter rod. The same principles apply with 1/8" and larger rod - I used 3/32 simply because I was already working on a project and had it out.

    fillet weld demo vertical up 3.jpg
  10. SCL

    SCL LawnSite Senior Member
    Messages: 543

    Nxt week Prof. 75 will teach us how to... Awesome description and I hung on every word. I am the typical farm welder and have learned a ton from your posts. this one was quite appropriate. How do you find time to post so much info and pictures. Don't stop, I was just curious:)

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