Step 11: Types of Welds
The easiest type of weld is the "fillet", two metals jointed at right angles. (The one shown in this instructable).
The next is the "lap" weld, which is two metals resting flat against each other.
Trickier is the "butt" weld, where two metals touch along the edges - it is difficult to keep the electrode traveling in a straight line along the joint, and tough to keep the weld pool going well on both.
Corners require some skill, as the heat is not dissipated evenly.
You can create "cosmetic" or "strength" welds.
Cosmetic welds tend to look more even over long lengths. Create them by making a weld pool, dipping in the rod, and then moving to the next point. Use them on highly visible joints, like on bicycles.
Strength welds are a lot stronger - use them for things that aren't designed to be seen, or are designed for strength rather than beauty. Anything that needs to bear a load (e.g., a gas cannister or propane tank) will have a strength weld. These are the welds where you simply draw the weld pool along continuously, while constantly feeding rod in.