[callganesh]

Hello,
I am currently using 4 flute 4 mm endmills to produce a helical groove profile on a 20 mm dia work piece using a vertical machining center which has a continous 4th axis rotary table. the groove depth is just 2 mm.
Since the endmill comes into contact with the workpiece from the top the poit of contact between workpiece and endmill is one small portion at the top.(something like a tangential contact). When I make the helical slot I get a line mark on the center of the slot which deepens after some parts.
I was suggested to use 3 flute endmills but still I find that line. Any ideas?

Rgds
Ganesh