grinding wheel composition?

[meenaggie]

Look at the figure on page two and notice the tungsten needs to be held pointing into grinding wheel. This is why it makes life much easier to use a drill to slowly spin the tungsten as described by others. (It is easy the hold the tungsten the other direction by hand but you may end up with a more dilute arc.) Also make sure to move the tungsten side to side in order to keep from making a groove in the grinding wheel. Other recommendation if you want get really serious is dedicate a grinding wheel for only tungsten to keep from contaminating it with other metals.

http://www.weldcraft.com/pdf/Tungsten-Electrodes.pdf