Mk3 Adjustable Tube Filament Guide

This filament guide uses a tube to constrain the angle of the filament as well as its position. 

This solves an important problem with the spool rotator that isn't solved by regular “ring” type filament guides.

When the print head moves across the print bed the filament changes angle with respect to an overhead spool.  A ring-type filament guide acts like a fulcrum and turns the filament into a lever that applies pressure to the overhead spool.  That is enough to interfere with the spool rotator. 

This also addresses a problem with small spools.  I often use 100g spools to hold the last of the filament on a bigger spool, to save space.  But, they are so small and light in comparison to the stiffness of the filament that they can unwind during a print, more and more, until there is a coil of filament over the extruder.   The tube prevents that from happening as long as it is close enough to the small spool.

You can use one or more of the 40mm or 80mm arm extensions to position the tube wherever you need.  And you can print one or more of the tube extensions to make a taller tube.  I found that one extension tube was perfect for my arrangement.

You can use the riser blocks to raise the tube higher.  This is needed if you use the spool rotator and want to print tall objects.  There needs to be at least 100mm from the bottom of the guide tube to the top of the extruder at the top of the print.

Assemble it with 4mm hardware. 

https://www.printables.com/model/523118-spool-rotator

Here's a quick video showing how the filament guide is aligned with the spool in use:

https://youtube.com/shorts/MYm2_QznfGw