This is hand wheels knob for CNC 3018 X and Z axis (diameter 8 mm). Printed grey looks very nice on machine.
Knob radius is 24 mm and thickness is 10 mm. It is meant to be used on 8 mm lead screw so it has 8.1 mm hole which is big enough that knob tightly sits on leading screw so it can easily turn leading screw.
There are holes for 3 mm headless screws if there is need to additionally secure knob on the lead screw. I find it not needed but I added them just in case. Holes are 2.5 mm in diameter and you have to cut threads for 3 mm screw. Screws have to be headless and 5 mm long or less. Screws should not be over-tightened to avoid destroying plastic threads. Use two screws on each knob for balance.
I remixed this from https://www.thingiverse.com/thing:9095.
https://pedja.supurovic.net/knob-with-knurled-surface-for-cnc-3018-x-and-y-axis-3d-print/
Using at least three vertical walls is recommended. Print hole up.
After print is done you may use fine sanding paper to soften the edges of kurling pattern if you find them too pointy and sharp.
Print time is about 45 minutes for two knobs in same job at 0.2 mm layer height.
The author hasn't provided the model origin yet.