Two more things. I use three hack saw blades to cut my nocks, but you have to be really careful when sanding that you don't open them up too much. I'm going down to two hack saw blades taped together the next time I self nock.
Your fear of slipping, I'm thinking you are worried about the arrow nock slipping up or down the string, can be brought to a halt if you set a nock stop above and below your nocking point on the string. You can use brass nock stops, dental floss tired w/ half hitches and wrapped and tied and so on, probably use string material, B50 etc., thread done the same way as the floss....finish all the thread style wraps w/ Duco or super glue, just like finishing a nock or point wrapping.
good luck, dpg