Pen holder for CNC

thingiverse

Pen holder for a home/hobby CNC machine. This device is specifically designed to work in conjunction with two 1/4-20 bolts, one of which screws into the flat side and is then chucked into the router's 1/4" collet. The other bolt is used to secure the pen or pencil in place. Neither of these holes has threaded interior passages. I printed this part at a 60% infill density so that it wouldn't flex while drawing and would provide sufficient material for the bolts to cut threads into. To calibrate your pen, set it up so that the tip appears to be directly aligned with the spindle center. Next, lower the Z axis until the tip makes contact with a piece of paper. Rotate the spindle/collet 360 degrees in its entirety. If the pen produces a complete circle during this rotation, you will need to make some adjustments. On the other hand, if it stays stationary and merely creates a single dot, your setup is correct. The pen holder's slot is dimensioned based on a standard Sharpie Permanent Marker, with an additional millimeter of radius incorporated to accommodate pens that are slightly larger in diameter. The side opposite the set screw features a tapered point designed to accept pens with smaller diameters as well.