Pen Holder for Fully 3D Printed Small CNC Router/Plotter

thingiverse

Here is the pen holder and stand for the ["Fully 3D Printed Small CNC Router/Plotter"](https://www.thingiverse.com/thing:3842401) It will fit fat Sharpies, Ultra Fine Point Sharpies and the Pentel Energels in the pictures. Really skinny pens may require longer screws. See PDF for print orientation. I used 4 perimeters for the pen holder parts, just 2 for the stand. The spring is a #156 from Ace Hardware cut in half. It has a 22.5mm OD., 72mm length., 0.86 dia. wire with 9 turns (counting the flat ones). Some post processing of the parts will be required for fit. The parts need to slide together without binding but the looser they are the more the pen will wobble when printing. I am planning on adding some finger grips to the holders. I hope to make changing pens easier, especially for small young hands. It is a little tricky to keep the spring compressed and tilt the slides in and out of the mount. When using multiple pens for a plot I post a separate NC file for each pen. I set the pens to the same length in the holders by setting the holder at a good Z height and then putting the pen in the holder and tightening the screws. Do this for each pen and holder without changing Z. You will have to experiment a little with your pens to see how much preload they like when you set the Z height for the job. You wan't as little preload as you can without the pen skipping. More preload means more deflection.