NX uses "rule of thumb" ratios to calculate depth of cut based on thickness of the wall. 8:1 for titanium, 6:1 for steel and 4:1 for the most flexible, aluminum. But these depths may not be stable, especially with long overhang endmills. Tap test to make sure you have the right tooth count and projection. You may need to lengthen the tool, counter-intuitively or use two lengths of tools to decrease cycle time.
