A Pen Carrier for Mounting a Staedtler Triplus Fineliner 0.3mm Pen to Sovol SO-1 Plotter Printer

 I don't have any experience concerning best pen(s) to use for plotting.  On some web searches, I saw that some other people using pen plotters had a favorable experience using Staedtler Triplus Fineliner 0.3mm black pens, so I ordered some from Amazon.  It turns out that these pens are triangular with fillets (essentially a triangle with rounded corners). 

The pen didn't seat evenly in the pen holder that came with my Sovol SO-1 pen plotter.  I took the pen holder off to examine it.  

The pen holder is 3d printed, it is made of plastic and there are layer lines.  There are two screws to attach the pen holder. 

One screw is 3mm diameter screw with a shoulder, which acts as a trunnion to allow pivoting of the pen holder.  Here are some rough dimensions I measured with calipers and scribbled down:

I'm probably going to misplace/lose this shoulder screw at some point, so I found an aliexpress page and ordered what I think is the same part, here is a screenshot:

The other 3mm diameter screw has a large flat knob that applies pressure to maintain the pen holder at a chosen angle relative to the Z axis carriage.  I scribbled down some dimensions I measured of this part as well:

The design aspects of the 3d printed pen holder to mount to the Z axis and allow rotation, I thought were quite good, I will call this part of the 3d printed pen holder the pen holder Z axis mounting bracket.  Attached to the pen holder Z axis mounting bracket is the 3d printed part which is used to hold the pen, which I will call the pen carrier.  Obviously, pens come in many different shapes and sizes so it is difficult to make a pen carrier that will nicely seat every pen.  On one end of the pen carrier is a screw with a knob which passes through an inserted nut on the right into the central cavity to contact the pen and push it against the opposite side.  The side of the pen carrier that provides a backstop to the pen appears to be a chamfered triangular shape (as if you made a flat cut perpendicular to one of the vertices of a triangle).  

I decided to modify the pen holder to better accommodate a Staedtler triplus fineliner 0.3mm pen.  I requested the STL file for the pen holder on the Facebook Sovol pen plotter group and May Young with Sovol kindly posted it on the Facebook files section.  I imported the pen holder into Fusion 360 and projected the geometry of the original pen holder Z axis mounting bracket to keep this part of the original design and redesigned the pen carrier part.   I designed the Z axis mounting bracket to have two captured square nuts in the X axis that accept 3mm screws. 

The square nuts for 3mm parts I used are low profile, I bought them on amazon previously:

I measured the Staedtler pen and made a 3d shape that could slide over the pen and adjusted the design until it could fit.  I added two female triangular pen shapes to the Z axis mounting bracket.  

This design so far, allows the pen to slide in from the top, constraining the pen's movement in X and Y dimensions but not in the Z dimension.  I designed a 3rd female pen shape to be placed over the pen intetween the top and bottom holders, with some of the stock removed off the back side so that the holding screw could push against it and there would be some clearance between the it and the Z axis mounting bracket.  

I created an additional 3d printed part for the tensioning screw, it has through holes for two 3mm screws to attach to the Z axis mounting bracket and it has a captured nut for a 5mm screw to push at a perpendicular against the middle female pen shape and prevent movement along the Z axis.  

The 5mm nut used in captured nut design, I purchased on Amazon (I did not use these M3 nuts):

I use a Cura plug-in that allows me to pause 3D printing at a certain layer height, add the nuts with a dab of ca glue, and then resume printing when ready.  These parts were printed in PLA and assembled and then mounted on the Z axis carriage.

Printed parts before assembly:

This is what the Z carriage looks like with the pen holder removed:

Right side view of the installed pen carrier:

Left side view of pen carrier:

Front view of pen carrier:

The 3D printed parts for this pen holder are shared in my google drive folder at the following link:

STL files for Pen Carrier and Z axis bracket

Disclaimer

The author does not make any warranties about the completeness, reliability and accuracy of this information. Any action you take upon the information on this site is strictly at your own risk, and the author will not be held liable for any losses and damages in connection with the use of this information.

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.