Welding help, lumber rack for truck

[whale]

Hi,
Hello to all! I am new to this Forum and look forward to exchanging knowledge and ideas. I have a Lincoln AC stick stick welder, 40-225 Amps, some people call it the lincoln buzz box. I have not used it much except occasionally for welds with quarter inch steel. I am trying to fabricate a lumber rack for my truck using one and a half and one and a quarter inch steel tubing. The wall thickness of the tubing is 1/8 inch and 5/64 inch. I have been practicing with small pieces to practice my welds and I am having a terrible time.
I am positioning two pieces of the tubing perpindicular to each other and attempting to weld. I am constantly burning through the piece of tubing that has the end cut on it. I am using 3/32 E6013 rod and I have tried between 40-90 amps with no success. When I do burn through the tubing that is end cut I also have the hardest time filling in the hole.
Any help on the technique and rod and amperage on this welding project would be greatly appreciated since I need this rack yesterday.
Thanks

[Pat]

I'd have to be there to try it to really help the most but here are a couple suggestion: 1. Try weaving, i.e. move the rod side to side while progressing in the direction of travel, spending more time over the "uncut" material than the cut end to distribute the heat and reduce that to the "end cut". This asymetric application of heat can help with what you are doing and for attaching thin stock to thick. Think of yourself as a zig zag sewing machine with an asymetrick sewing stitch dialed in. or 2. make some "U" chanel to "wrap" around the joint as a doubler. Weld the uncut tube to the chanel and weld the cut tube to the chanel. Yo will be welding the cut tube away from the cut end so it won't be so sensitive to "burn through." A variation on method 2 is to lap the two pieces to be joined with a "doubler" on each side which is welded to both pieces of tubing, again eliminating the task of welding materials with markedly different thermal properties.
This would be an easier welding job if you had a wire feed MIG with flux cored wire but even with my MIG I find weaving etc to be valuable.

I too have burn through problems with light materials and have had altogether too much practice filling holes. If my welding technique improved as much as my hole filling I wouldn't have many holes to fill.

[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]

[whale]

Hi Pat,
Thanks for the tips on this stick welding welding project. They make a lot of sense. I would like to be able to weld this together without the use of the extra metal but I will use that as a last resort.
What about the 6013 3/32 rod I am using. Do you think that diameter and rod are ok for this project. What amperage would you use.
Also what is your technique for filling in the holes from burn through.

[GERARD]

6013 is pretty decent rod but it's got pretty good penetration too, which, in your application you don't need. Try a 7014. It's called mud rod and had iron fillings in it and leaves a pretty big bead behind but not too much penetration. The stuff you're welding is pretty thin so use the least amperage you can and still strike the arc. (I have the same unit as you). I also think you can get a 5/64 rod (not sure about that) but 1/16 would be too small + 1/16 is EXPENSIVE. Try the 7014, might do the trick. Increasing your speed will also work, it's just a atter of getting the right feel. As far as filling holes I just strike the arc, leave it there for a second, pull away to let cool, and do it again. Each time you leave a little material behind and the hole is smaller. Tends to leave some slag but I worry more about sticking the stuff together than making it pretty.

[whale]

Thanks for the info about the 7014 rod. When you are filling those holes do you need to remove the slag between each pass with the rod.

[Pat]

Whale, I'm sorry but you have mistaken me for a knowledgeable welder.

I have a chart on the inside cover of my MIG that tells me how to set it. The side of my Lincoln AC/DC welder (like your little red buzz box but with DC and DC reverse capability also) has a chart that recommends settings for various electrodes. I am virtually totally self taught from trying things and reading. I have read a lot and have watched a few experts. I always learn something watching a good welder.

Since I am prone to blow holes in thin metal I have lots of experience trying to close the holes. I have spent the better part of an 8 hour day trying to weld a VW bug gas tank that was corroded thin. I got close and then made my first ever brazing job to seal the residual pinholes after doing my best with the MIG. (I used liquid plastic to line the tank and it should never rust out again.)

When I am closing holes it is usually for cosmetics and not for great structural strength. I set the heat (amperage) on the low side to deposit the maximum metal with minimun melting of the substrate. I tend to rotate the electrode in a circle around the edge of the hole, ONE PASS ONLY(sometimes two but three or more is asking for a bigger hole), wait for it to cool a few seconds and make another circular pass or two. As you continue this you gradually close up the hole. Patience is a virtue. Make haste slowly. Trying to do too much too fast will end in a setback. Eventually you will have kinda sorta got some "bird droppinigs" quality of weld over the hole. This elliminates the "edge effect" where the edge is much more easily melted than continuous substrate.

Now you can up the heat a tad and go back over the hole being slightly more aggressive but still with come interspersed cooling cycles. If slag inclusions aren't a bother, this goes without a lot of chipping and grinding. I don't typically weld pressure vessels or high pressure piping so I don't worry about the "X-RAY" quality of my welds all that much.

Real welders ship this part!

I have been known to hold a second elctrode or two in my other hand to use as "fill" rods like with gas welding. brazing, or soldering. This is another technique that helps close up holes. I bridge the hole with side by side pieces of elctrode which I fuse together with subsequent passes.

When I first started out with a stick welder I went to a scrap yard and bought a bunch of small scraps of steel; bars, pipe, sheet, chanel, angle, etc. I experimented with welding pieces together and then smacking the crap out of them in a vice using a sledge hammer (AKA destructive testing) and soon found things that worked a lot better than some other things.

So far my greatest accomplishment was to weld a broken cast aluminum table leg back together with a stick welder using flux coated aluminum welding rod. I used aluminum window screen scraps as extra filler material.

I really wish I had taken a some classes on welding and may, some day. Reading and practicing are also good if there just is no way to take a class.

[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]

[GERARD]

I don't worry about the slag when filling a hole. You will get some inclusions but the material you're working on is so thin anyway strength is not likley a huge issue. If it were the material wouldn't have burned through in the first place. Using some filler material is also not a bad idea (brazing rod works well, just strike the arc and feed the rod injust like you would is you were oxy ace welding

[rdbrumfield]

thin material means using the smallest rod and the lowest amps that you can get away with. Trying to weld light material with a buzzbox is a challenge with folks that know what they are doing. 6010 is a rod that I am familiar with that is easy to strike so you can do small spot welds as you go to keep the heat down and not burn through the parent metal. I'm so used to my mig I have forgotten the pitfalls of ac welding.

[Fred]

How much of the round tubing do you have? Too much to switch to square tubing? That's what I always made ladder racks out of. If you're committed to the round, you could always grind a contour into the two sides where your fillet weld would be and that would close the gap, too.

Pat gave some great advice on filling a gap. To explain what I always did is very similar. I placed tacks on either side of the gap in basically one pass. As the one is cooling down it will glow enough for you to find another spot to scratch your stick and will eventually close the gap. Zig-zag from side to side. If you blow a hole it can be filled in the same manner or you can also try to "draw" a circle around the hole working toward the center and lifting your rod slightly to reduce the voltage/heat as you get to the center. You should get a nice puddle with a lot of filler, but it will take a while to cool. Get a little swirl going.

I always cleaned the slag from my welds. Welding on top of slag causes a mess which in turn weakens your weld, even if you finish off with a decent coverpass. Sort of like a house only being as strong as the foundation. You don't want to be thinking about the strength of your welds when you have a dozen 8x8's on top of your rack going around a corner or swerving to miss something.

Good luck