Ok, welding 101. Gas, electric arc, heliarc or wire welders. Thickness of the pieces being welded. All of these will affect the look of the weld your trying to model. Welds on thin pieces such as soft skinned vehicles will be raised, penetration not being a problem and the welder can move along pretty fast. Where thick armor plates are mated a bevel is usually made to allow penetration the full depth of the weld. This take a bit longer and because of the bevel you may see that the weld is below the level of the plate or at most even with it. Aluminium (damn I think I speeled it right) requires a gas to prevent the weld metal from oxydizing too fast and causing blowouts. The gas also helps to cool the weld quickly. These welds are usualy wider than other welds and smooth rather than sharp and wavey. Heliarc and wire welders are fed from spools of wire so the welds are pretty much uniform their whole length. Stick welding requires the replacment of the welding rod periodically and this may cause variation in the width of the weld for a short lenghth after the welding resumes. Remember that a good weld requires that the adjacent material be heated to melting temprature to properly bond with the rod or wire material. In some instances a carbon arc is employed which does not melt, then it is the material of the two mating surfaces that form the weld. Why the weld looks wavey? Actually the welds or passes are horse shoe in shape. As the rod or wire melts and the stock material melts the mated material tends to runout or flow away. To prevent this and keep what your welding where you want it you have to keep the arc or torch moving. Move it too far away and the weld cools off, stay too close and the weld melts away. The horse shoe pattern allows you to stay in the weld and keep the material hot enough to begin melting when you want to start welding there. It just looks like continuous waves or circles because the trailing weld has been over passed by the next weld. This is what you want to model, the circles or arcs. A good weld will be uniform in width, height and the spacing of the arcs. A good weld between a vertical and horizontal should be coved. If not there is poor penetration.