Showerthought: My weld beads looked great today, but why does penetration depth vary? | Boilermakers - Freelance Forum - The Community for Independent Professionals
Heard an old-timer say a steady hand is just one piece of the puzzle. If your travel speed varies even a little, it totally shifts the heat on the puddle. That changes how deep it goes in, same as if your arc length gets long. Honestly, most welders chase the perfect angle but forget about their speed. Focus on keeping a consistent pace and a tight arc, and penetration usually sorts itself out. Makes sense when you watch the puddle instead of just the rod.
Forgot to mention rod angle relative to the work surface changes things too. A real steep drag angle focuses the heat more directly (like pointing a hose) which can punch deeper even if your speed is steady. Saw a guy run too flat on a fillet and it just washed over without biting in.
Notice how many skills look simple until you try them. Welding, cooking, even driving a car all have tiny details that change the whole result. It's why experts make hard things look easy.