This is a modification of my first spindle mount designed for 60mm rail used on the OX CNC. On this bracket the holes are positioned to fit an 80mm rail used on the popular C-Beam based machines.
It will be made in 10mm (base) and 20mm (bracket) aluminum. I will try to make it available on makersupplies.dk early 2019.
Update: Now available here: 43mm Spindle Mount for C-Beam Brackets
Fusion360 link: A360