Here is the mount I am using on my SMW3D R7 CNC. It holds an 80mm OD water cooled spindle to an 80mm section of openbuilds vslot or in my case C-Beam.I also have a 65mm OD version for those with the smaller sized spindle.I am including the STL's, original solidworks models, as well as step and x_t models to help others use and modify it as they needIt clamps down using three 5mm screws, and the pockets in the back half are to accept openbuilds t-nuts to distribute the clamping force.I printed mine in PETG, 5 perimeters, 50% infill. I know it is a printed part on a CNC... but in PETG this is one tough mount.