I am trying to machine an elliptical bore in annealed PH 17-4 round stock (see photo below) with a Haas TM-1P. The part is held in custom aluminum soft jaws. The bore is around 1.5" diameter and I am using a 3/8" 4 flute AlTiN Kyocera end mill. I've roughed most of the stock with a radius endmill, leaving around 8 mils of radial and axial stock, then I come in for the finish pass with the square end mill.
The central rod shown is cut in the same pass with the same tool and comes out with a very nice surface finish. However, as you can see in the picture, the outer bore is faceted/wavy. I have tried a bunch of different things to improve the surface finish - faster and slower feeds, multiple depths, spring passes, climb and conventional milling, and even different toolpath smoothing options. None of these changes did anything - the patterns is very consistent.
Any ideas?
Thanks!
Ben
The central rod shown is cut in the same pass with the same tool and comes out with a very nice surface finish. However, as you can see in the picture, the outer bore is faceted/wavy. I have tried a bunch of different things to improve the surface finish - faster and slower feeds, multiple depths, spring passes, climb and conventional milling, and even different toolpath smoothing options. None of these changes did anything - the patterns is very consistent.
Any ideas?
Thanks!
Ben