The CNC 3018-Pro normally holds a small DC motor with a nicely cylindrical housing,so this was an easy adaptation of the MPCNC’s diamond drag bit holder:
The lip around the bottom part rests atop the tool clamp, with the spring reaction plate sized to clear the notch in the Z-axis stage.
The solid model looks about like you’d expect:
The New Thing compared to the MPCNC holder is wrapping LM6UU bearings around an actual 6 mm shaft, instead of using LM3UU bearings for the crappy diamond bit shank:
I cut the shank in two pieces, epoxied them into 3 mm holes drilled into the 6 mm shaft, then epoxied the knurled stop ring on the end. The ring is curing in the bench block to stay perpendicular to the 6 mm shaft.
The spring constant is 55 g/mm and it’s now set for 125 g preload:
A quick test says all the parts have begun flying in formation:
It’s definitely more rigid than the MPCNC!
The OpenSCAD source code as a GitHub Gist: