When I ask for the best I mean the one which explains better the experiments. My problem is that I tried to learn but I´m a bit confused, I know that metal cutting theory has a large history, and it has had a lot of experimentation but when I try to find the theory it´s like it wouldn´t exist a model which explains every kind of situation (different materials, geometries...) I mean Merchant proposed in 1941 a model, but it was not realistic and it didn´t agree with experimental data, there have been a lot of attempts to modify this theory in order to eliminate the problem but I don´t know if it has been achieved. I have read Victor Astkhov´s website and he criticizes a lot of models. I´m not going to classes so I´m alone at this, I only have internet. Anybody could show a general picture about the "state of the art" in metal cutting theory?. Thanks!