My X-Carve has been upgraded a lot since its purchase but the general idea should still apply to your ( vanilla? ) one.
Below is a picture of my Microsoft Surface Dial’s Delrin Transport Case I made a few weeks ago:
Before cutting the chamfer, the vertical surface had a total length of 19mm which is close to 3x the diameter of the ONSRUD 52-080 ¼" 2F UpCut Endmill I used to do like 90% of the OPs on the shell.
In order to get this, IMHO, really nice finish I split that particular OP up into 4 parts:
- Four 2.375mm cuts to half the 19mm full depth with 2 Multiple Finishing Passes of 0.66mm, Finish only at final Depth and 0.25mm Radial Stock to leave - So 4 cuts at 2.375mm each and the 5th cut at 9.5mm.
- Two clearance cuts to half the depth with 1.5mm Radial Stock to leave.
- Four additional 2.375mm cuts starting at half the 19mm full depth to full depth with 2 Multiple Finishing Passes of 0.66mm, Finish only at final Depth and 0.25mm Radial Stock to leave - Again 4 cuts at 2.375mm each and the 5th cut at 9.5mm.
- One final cut at 19mm full depth with zero Radial Stock to leave but a Repeat Finishing Pass at 1/3 the feed rate.
Here’s a short Video visualizing it ( Step 2 Clearance Cut not shown ):
Alternatively, you could also model a channel and use an Adaptive Clearing OP to clear it out which would allow for cutting depths of 1½-2 Tool Diameters ( or more ) at once.