I can honestly say i ran a turned crank when i was 16 with no problems but i dont recomend doing it . See machine shops have what they call standar limits and they can be to tight or to loose. I would not be as so much worried about the strenght of the crank as you cant get one done right and get the right bearings for it . I just tore one down built with a turned crank by another builder just to check it out because it had alot of problems . Bearings were so tight no way it would have made it through break in . Save yourself time and money and buy a good stock crank man.