If you are taking a plate test on carbon steel, then you are probably attempting a Welder Performance Qualification in accordance with the AWS D1.1 code.
If this is so, this Code does not recognize spray arc transfer for the vertical and overhead positions. This is because, in the spary arc mode, the puddle is too liquid to shape into an acceptable bead for these positions. Yes, you may shape a bead by repeatedly breaking the arc, which is essentially placing individual tacks in a row, but this is not Code compliant.
Therfore, you need to turn down the machine to weld vertical and overhead in the short circuiting transfer mode.
Vertical Mig has a tendency to bunch up in the center of the bead and drip downward. To avoid this, you need to dial in the settings on your paticular machine just right and use a weaving motion. Keep in mind though that you may not place any single, weaved bead over 1/2" wide. As many machines burn differently, I recommend that you find the setting you need to use on a practice piece or two before starting on the test plate. You may need to turn the machine down a little while capping off the bevel as your test plate is heated up and without the sides of the bevel to help hold the bead, it is a little harder to control. You should be testing to the parameters predetermined by a WPS (welding procedure specification). When adjusting your machine, be sure that you stay within the range of parameters detailed in the WPS.
Overhead is not much different from Vertical, maybe even a little easier to control the bead shape. The tricky thing about short circuiting overhead is dealing with all the spatter falling down your shirt collar and collecting in hot piles on your arms. This can be distracting... Additionally the spatter will quickly clog the mig gun nozzle which prevents even flow of the sheilding gas. Things to remeber are to hold your body and the nozzle at an angle rather than directly beneath the puddle so the spatter will fall elsewhere.
Hope this helps.
Tim
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