Spine dragchain - improvements

This is a remix of Maxdarkdog's Spine dragchain. I liked the design and decided to print some links as experiment. After the print I had some suggestions and instead of asking for them to be implemented I decided that it would be easier to make them myself, print and test clearances and such.
I had to recreate the files in FreeCAD for easy editing so you also get the source as well.
The changes I added and why (from right to left):
1) chamfer at the bottom edge - no elephants foot and clean