Mendel Pen Holder

I had problems using the original pen holder on my Prusa, see http://apapageek.blogspot.com for details.

So I used the original STL file as a template for reworking the design in OpenSCAD. Along the way I made a few changes to make using the pen holder easier.

a) Redesigned the top bracket so that there are channels to guide the rubber bands and a loop to hold them captive. Now if there is a balance problem, or when you take the pen out the bracket does not try to orbit the room.

b) Made the holes for the elastic band capture bolts on the top further away from the body, this made it easier to install the elastic bands.

c) Made the bottom tube longer, this should solve my problem of the pen tip being too close to the X-carriage.

d) Turned the top plate to bottom plate mounting holes through 90 degrees and sliced the sides off the circle, this allows me to mount it on my Greg Frost X-Carriage.