Weird Constructor / Posts / Filament Spool Holder Problems and Re-Design

Filament Spool Holder Problems and Re-Design

As first post on my site I welcome you with a short description of my self designed filament spool holder and how and why I designed my own:

My swing at a design of a ball bearing based filament spool holder
My swing at a design of a ball bearing based filament spool holder

My first printer was the Anycubic i3 Mega, it came with an acrylic spool holder like this one:

Anycubic i3 Mega arcylic spool holder
Anycubic i3 Mega arcylic spool holder

It works fine and I never observed much problems with this one. The i3 Mega is doing it's duty fine since 2018. Christmas 2021 I finally got my next FDM printer, because the Prusa Mini had deliverytimes of about 2 months I decided to try a much cheaper variant. The Kingroon KP3S was available for just 177€.

It arrived quickly and I only had to calibrate the extruder e-steps. I got the KP3S Version 3.0 variant with a Titan extruder (or a clone of it). Here a picture of my current 3D printing setup which fits nicely into my DIY shelf:

My current Kingroon KP3S setup
My current Kingroon KP3S setup

It came with a very simple and also common design of a spool holder. It consists of a few ball bearings mounted into a light piece of plastic:

Kingroon KP3S filament spool holder
Kingroon KP3S filament spool holder

I only tried to use it for short while, because I quickly encountered the first issues, especially with rather empty spools:

Some spools might have stiff filament or bad winding and can be pulled off

The ball bearings were not very smooth-running, but the problem is also that the plastic holders tend to shift around on the desk. So I decided to print a very simple filament spool holder design from Thingiverse: Filament Spool Holder by zachlothe:

Remix of the Thingiverse Filament Spool Holder by zachlothe
Remix of the Thingiverse Filament Spool Holder by zachlothe

I just lightly remixed it in Blender to make a few cutouts on the bottom and scale it down to make it fit on my KP3S. Printing time was about 9 hours. And I used some left over pieces of PLA filament (hence the two colors).

However, it I observed another problem with this spool holder. The KP3S direct drive extruder seemed to have difficulties pulling the filament evenly and so I got uneven layers, which are visible on the left side in the following picture:

Uneven layer extrusion, on the left is the thingiverse spool holder, on the right my new design.
Uneven layer extrusion, on the left is the thingiverse spool holder, on the right my new design.

The following two short video clips demonstrate other problems with the spool holder. Such as with too light spools the holder could be easily pulled towards the printer. And a heavy spool would not unroll smoothly:

With a heavy spool you get a very uneven rolling, putting uneven force on the extruder.
The light spool works better, but the holder is too light and moves easily.

Inspired by many alternative designs on Thingiverse I sat down and designed my own take on a filament spool holder. I had a few M8 screws at hand and I wanted to screw mount the spool holder to my shelf.

My swing at a design of a ball bearing based filament spool holder
My swing at a design of a ball bearing based filament spool holder

You can find the Blender file and the STL files in my Git repositiories:

You may wonder: *Why call it a generic spool holder? Well thats because it's not a mount for a specific printer, and it will work with almost all filament spools. The dove tail connector will make it future proof for other mounts, such as printer specific mounts or even a desktop stand. I plan to add these at some point.

Here is a short manifest of the required STL files and parts:

My swing at a design of a ball bearing based filament spool holder
My swing at a design of a ball bearing based filament spool holder

And here how it is assembled:

Generic Filament Spool Holder Assembly
Generic Filament Spool Holder Assembly
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Weird Constructor

Nice end 30 y/o guy, geek and F(L)OSS developer that messes with: Linux, Windows, Networking, Interpreters/Compilers, Games, Audio, GUIs, C/C++, Rust, Scheme/Lisp, 3D printing, electronics and more.


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All the F(L)OSS development on my projects happens in my spare time. If you find what I do useful, entertaining or just want to support me, you can do this via Liberapay:

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