I start with a flat top on the saddle. I sort of already know my points because I use the S.M. intonator device to get those. Then to home in on the saddle I string up, I use a piece of the string paper and run it under the string so I can see exactly where the string is comming off the saddle top. Then I read my intonation and mark my points accordingly. Then I cut the points, string back up and check with the paper again. I realy like using the intonator because my saddles never end up where you "normally" would cut the slot. I install Buzz Feiten on every guitar I build and that makes any type of pre-slotting almost impossible.