I have an updated video on this topic using FreeCAD's built Super Secret built in Threadmilling feature. Some of this still applies such as using separate files for swapping tools.
   • FreeCAD Super Secret Threadmilling CA...  

In my learning about CNC machining, I have chosen FreeCAD as my primary CAD & CAM tool. I wanted to do Threadmilling on my Desktop CNC machine, but could not find much info online about it in FreeCAD. So I got to work figuring it out. FreeCAD has not fully implemented this as a feature. There are some FreeCAD issues and quirks, but you can work around that and this video shows you how.

FreeCAD version 20.1 and 21.1


0:00 Intro
1:51 FreeCAD Test Model
2:38 Thread Measurements
6:00 FreeCAD Threadmill bit model
7:30 CAM Tap hole
8:46 CAM Thread helix
9:28 Thread cut calculations
10:58 Threadmilling issue in FreeCAD
12:00 Threadmilling fix in FreeCAD
14:28 Finish Threadmill pass
16:30 Simulation
17:46 Tool change solution
22:34 Test #1
24:26 Fix GCODE issue
25:40 Test #2, file #1
26:09 Change tool and run file #2
26:52 Success!