Parametric pen holder for CNC

This is a pen holder for your CNC. There is no moving parts (hence no mechanical play), no spring needed as it's the ABS part that is acting as a spring.

It's designed to be sturdy in X and Y direction but flexible in Z. It can be preloaded with a an ajustable screw (as seen in the photo between the bottom leg and the extruded aluminium).

I preloaded mine at 5 grams, that's enough to write with my pen, and thanks to this preloading I only need to move my Z axis by 0.3mm up and down to write and stop writing. But if you go further down it doesn't damage anything as the ABS part will bend and keep a moderate pressure on the pen.

I tried to go down 1mm after contact and the force increase from 5 to 10 grams. So you don't need to have a perfectly accurate machine to draw consistently.

OpenSCAD model included so you can adapt it to your machine.