I continued with my stick welding in class today and was able to complete two of the three assigned tasks. I was able to complete a steady bead of 3016 stick on a 3/4 inch 4×4 steel plate 8 times in a row. I was also able to completely cover a 4×4 plate with overlapping
beads, keeping them all pretty straight. With each pass you cut into the previous row by 1/3 of the width of the original bead, so that when you have two rows complete, the first row is only showing 2/3s of its width and the second shows its whole width. The second exercise was not necessarily a real world example, but it shows that your straight bead is repeatable and that you can manipulate the previous bead with your new molten pool of metal without totally screwing things up and compromising the integrity of the original weld. Lincoln Electric has a nice article here on creating high quality stick welds.
The third exercise was a butt joint where you lay two pieces of 16 gauge metal flat on your surface, side by side with a gap between. The gap should be approximately the size of the stick that you are using as the filler material. So, since we were using 3016 stick, you lay the stick in between the to pieces of metal to get your correct gap. The trick here is that each stick has a coating on it and you should NOT include that in your gap width. You need to either eyeball the gap or use the mall one inch end of the uncovered stick as you guide (one end of the stick is uncoated so it makes good contact with the electrode holder you grip when welding).
The cross-section of a welded butt joint, with the darkest gray representing the weld or fusion zone, the medium
gray the heat-affected zone, and the lightest gray the base material.
My gap was a bit too big and I was spending too much time in one place, so I kept burning through and could not get the desired ‘keystone’ weld. A keystone weld is where after you complete the weld you theoretically could pick it up, hold it between your fingers and look across the flat surface of the metal weld. You would look right into the gap from one end of the metal and see a nice bump across the top of the weld, the gap totally filled with metal and just a tiny round metal fill coming out the bottom of the gap. Having the tiny metal fill coming out means you had total penetration in your weld and those two pieces of metal are bonded across the whole gap.
I only had about 45 minutes to practice that one so I did not get very far, plus it was not all weld time. We were trying to conserve (not waste) metal so after an attempt we would go over to the punch press and cut the metal to give us another set of surfaces to practice on. A little bit of info that I learned about the weld and the punch press, you should NEVER cut across a weld. When you weld, the metal is forged so that it becomes harder than it was originally. If you try to cut across a weld, the weld will usually win and your blade will loose. It is cheaper to get more 16 gauge and very expensive and time consuming to replace the blades on the press. Don’t cut across welds.
After watching the speed skaters at the Olympics, the process to weld a butt joint makes more sense to me. You have to touch each side of the weld and move across the gap to the other side wile moving down the gap towards your destination. I picture the skater with a piece of metal on each side of his path down the ice. He must touch each side with one of his skates as he moves forward but cannot spend much time in contact with the metal. So touch right side, touch left side, touch right side, touch left side, on and on until you reach the end. You don;t need to worry about filling the gap as the melted metal from one side will naturally flow down into the gap as you slide over to the other side. Notice I did not say jump you as you want to keep you distance to the work constant. Moving too far away from the work causes your arc (picture orange lightening) to jump around and spray your nice pool of molten metal to areas you did not intend.
I will pick this task up next Saturday and have the picture of Apolo Anton Ono or C.J. Celski in my mind as I ‘skate’ across the gap and bind the butt joint.
Today we were introduced to Shielded Metal Arc Welding. The first two and a half hours of class were concepts and video demos while the second hour and a half was actual hands on practice time. The flow of this new process took a little getting used to compared to last weeks Oxy process. SMAW requires a consumable metal rod instead of just a flame from a torch. With Oxy you just need to worry about keeping the flame the correct distance as you move across the work. With SMAW, the rod is used up (deposited) onto the work surface, so your hand(s) are getting closer and closer to the work as you use up your rod. It took a little getting used to but after about 30 minutes I was comfortable moving left to right (I am right handed) while constantly getting closer to the work surface while keeping the arc (electric spark or heat source) 1/8 to 1/4 inch from the work.
