Grind along, never across
This is the rule that matters. Grinding marks that run around the electrode make the arc wander and split, because the arc follows the ridges; marks running lengthways channel it to the point. Hold the tungsten pointing into the wheel and roll it, rather than presenting it sideways.
Angle by job
A long, fine taper — roughly two and a half times the diameter — concentrates the arc and suits thin material and low current. A blunter taper carries more current without the tip melting back. On AC for aluminum the tip balls slightly in use, and that is normal; do not fight it.
Use a dedicated wheel
A wheel used on steel embeds iron particles in the tungsten, and those end up in the weld as inclusions. Keep a small wheel or a diamond disc for tungsten alone. Diamond is better: it cuts rather than rubs, so the tip does not overheat and micro-crack.
Grind before you need to
A tungsten that has touched the pool is contaminated, and welding on regardless drags that contamination into the bead. Keep three or four ground and ready — stopping to regrind mid-weld is how a job gets abandoned.
The questions welders ask
How much should I grind off after touching the pool?
Enough to remove all discoloured or bulbous metal, which is usually 2 to 3 mm (0.08 to 0.12 in). Contamination is not just on the surface: the aluminum or steel that touched the tip has alloyed into it. Grinding a little and hoping produces a wandering arc and a dirty weld.
Do I need the expensive tungsten grinder?
No, but a dedicated wheel is not optional. A bench grinder with a fine wheel kept only for tungsten does the job; the dedicated grinders exist to give a repeatable angle and to contain the dust, which matters if you grind thoriated tungsten — another reason to use lanthanated instead.
Last reviewed 2026-08-14