Picking an Axial Depth of Cut
Stepdown, or axial depth of cut, is how deep a milling tool plunges into the material on each pass. Conservative roughing typically runs around one tool diameter per pass, balancing material removal against tool deflection and chip evacuation. High-efficiency milling strategies push this much deeper, often two times the diameter or more, but only when paired with a lighter radial engagement and a rigid, well-supported setup.
Finishing Passes Need Less, Not More
Finishing passes use a shallow stepdown, often around 10% of diameter, because the goal shifts from removing volume to controlling surface finish and dimensional accuracy. A shallow axial engagement on a finish pass reduces deflection-driven taper and chatter marks on the wall.
Watch Your Flute Length
Whatever stepdown a strategy calls for, it only works if the tool's flute length (length of cut) can physically reach that deep without rubbing the shank against the wall. This calculator flags when a chosen depth of cut exceeds the tool's usable length, which usually means either picking a longer tool or running the feature in more passes.