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 T...
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!