Geometry of end mill cutters plays a vital role in the stability of the flexible parts milling .The present study considers helix angle and number of flutes .Multi‐frequency solution is established to draw stability Lobe dia‐gram (SLD) for different helix angles and number of flutes .SLD for the two cases shows that the greater the value of helix angle ,the more stable the milling process will be ,and conversely increasing the number of flutes degrades the stability of flexible parts milling .A simple empirical methodology is adopted to employ the inclined plane workpiece geometry offering a gradual increase of the axial depth of cut in the feed direction .Surface roughness is used as a measure of stability .Test results corroborate the model conclusions very well .