Update: Added a spacer for the "Mark2" - See project updates down below!
Original Text
Right after l got the Prusa i3 MK2 up and running, I noticed one major flaw of that otherwise fabulous machine:
The spool holder!
Not only that it looks not as well engineered as the other parts of the machine, but it is also not very convenient regarding usage. Especially if you want to do layer based color printing you have to switch the filament quite often during one print. Bending the original spool holder to release the mounted spool, as well as adjusting it to hold the new one in place (especially if the spools width differs from the first one) is time-consuming and tedious.
There are already a few alternatives here on Thingiverse, but after trying a few of them out, I found that they have some other issues.
- Their wheels are often mounted using printed hexagonal screws and nuts. This results in the need for tools like a wrench to tighten them up.
- The mounting to the metal frame of the Prusa i3 MK2 is often not well designed. Most of the alternative spool holders rely on pure force to clip the holders onto the frame. This has two consequences:
- The required force is not good for the printer's construction, nor the printed parts, that can easily break (as happen to some of the spool holder arms I printed).
- It makes adjustment for other spool widths very hard.
- If the extruder reaches a certain hight on the z-axis it could crash into the overhanging construction.
- ... it is an all tool-less design. All parts are just slid into each other. The nuts can be tighten by hand.
- ... the arm's clamping design is optimized for an easy attaching onto and detaching from the printers metal frame, with as little strain on the parts as possible. This makes also the width adjustment very unproblematic and fast.
- ... due to the small footprint of the holder's arms, you can mount two spool holders side by side. The end of the idle filament thread can be locked placed into the hole of one of the axis' screws. This prevents the spool from uncoiling and tangling up.
Please also take a look at my other designs, printer parts and tools.
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