So I had a fingerboard that I tapered before slotting (before thinking too apparently) and that presented a problem since there were no more 90's on the board!
Drew up a pocket 1/8 deep and the board fits like a glove. Programed the frets to a 34 inch scale and turned a .023 end mill loose to cut 25 slots, .09 deep via 9 passes at .01 each turning real fast and moving real slow through the Wenge I selected.
21 slots went fine then the bit broke a little but had enough left to cut a pass about .02 or so deep so I had to finish it by hand but at least they are all dead on and I didn't have to cut them all by hand.
It is nice to have access to a shop bot.