Project - Tool Free Spool Holder For The Original Prusa i3 MK2 Project Tool Free Spool Holder for

Having the original Prusa i3 MK2 for a couple of days now, 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, it is also not very convenient in terms of 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.
So I designed this spool holder, where the spool is laying on four wheels that roll smoothly on 608 (skater) bearings and hopefully eliminating the previous drawbacks. Speaking of which, ...

... 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 optimised 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 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.

To make the spool holder work, you need four 608 bearings for one set, that you can get from a local skater shop or from Amazon (by using the provided links you can support me and my work):

* Amazon.de: http://amzn.to/2euVdTK - 8x 608 ABEC 9 bearings as used on my prints
* Amazon.co.uk: http://amzn.to/2eTLSt4" - 8x 608 ABEC 9 bearings, similar to the ones I used

You often find eight bearings inside a set, which is enough for two spool holders.

The spool holder is designed in a way, that you can use all parts for both sides of the holder and also switch the axis screws from back to front and vice versa. If you like to have the "smooth bed side" oriented to the outside, you have to mirror the right arm along the x axis.

For the infill I used a honeycomb pattern, because it matches the hexagonal style of the holder and my filament is quite translucent. Honeycomb gives good mechanical support in general.

I printed with three perimeters for all small. Four perimeters were used for the arm and six perimeters for the wheels to avoid infill there. Each part has four top and bottom layers on my prints.

Even tough I printed my final design in 200µm (0.2 mm) layer resolution, I also tested 100um (0.1 mm) for the wheels. That gave them a really smooth finish, but it had no effect on the mechanical properties.

More details on http://www.thingiverse.com/thing:1832235

Видео Project - Tool Free Spool Holder For The Original Prusa i3 MK2 Project Tool Free Spool Holder for канала Martin Majewski (net)