Actually, what is needed is a slotting saw, not a slitting saw. You can slot with a slitting saw, but can't slit with a slotting saw.

Jeweler's slotting saws commonly start at 0.008" and go up from there.

Victor tools again is your friend, offering jeweler's slotting saws in several diameters.

http://www.victornet.com/subdepartments/Jewelers-Saws-1-1/2-to-1-3/4-Diam./1591.html


Jim H.