Question 1

How do I choose the optimal stepover for 3D finishing?

Accepted Answer

Start with the required surface finish (Ra). Calculate the maximum allowable cusp height (h ≈ 4 × Ra). Then calculate stepover from the cusp height and tool radius. Apply a 50% safety factor for the first test cut. For Ra 1.6 μm with R5 ball end mill: h = 6.4 μm, theoretical stepover = 0.51 mm, practical starting point = 0.35 mm. Adjust based on actual surface measurement.

Question 2

Does surface inclination affect cusp height?

Accepted Answer

Yes, significantly. On steep walls (near vertical), the effective tool radius increases and cusps become smaller for the same stepover. On flat/shallow surfaces (near horizontal), the effective radius decreases and cusps grow larger. Five-axis machining maintains a consistent tool contact angle (typically 10-15° tilt) to produce uniform cusp height across complex surfaces. Three-axis machines produce variable surface quality depending on surface orientation.