Mendel Pen Holder
by geoffd123, published
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.
Print the parts, I used Slic3r with 3 perimeter walls and an infill of 0.65.
Hold the top and bottom together and insert your pen as an alignment guide. Fasten the top to the bottom using 2 20mm M3 bolts with 4 washers and 2 nuts. Remove pen.
Pull the 2 elastic bands though the top bracket retaining holes using something like a paperclip or a thin piece of wire.
Feed the ends of the elastic bands into the top retaining slots and secure with 2 20mm M3 bolts, 4 washers and 2 nuts.
Mount the holder on your X-Carriage.
Insert pen push firmly into holder and secure using the top bracket.
Print your PCB.