I am doing 4th-axis milling for the first time. I am roughing out a small cylinder (OD 1.75" and a length of 0.75") with a 0.25" end mill. I am using DeskProto for the CAM side and it gave an estimated time of about 45 minutes (490 inch tool path with one tool with about 1,400 lines of code). When I put the code into Mach3 and I simulate the run time, it says 16+ hours! On the 3-axis operations the time estimates from DeskProto matched the Mach3 estimates and actual times fairly closely.

Does anyone have any idea as to what might be going on?

Greg