Magnetic interchangeable printheads for the DICE
Who knows my video from 2015, where I show off a magnetic hotend changer for the sparkcube, you are going to have a Déjà-vu now. I made a very similar system to change the printhead for the tiny printer DICE.
There is only one printed part to change, the part "x_carriage_hotend_holder_1x.STL" with a combination of two matching new parts. You can find the relevant parts in the dropbox folder "printed parts/optional". Furthermore, you are going to need at least 4 magnets and two magnets more for every additional printhead you are going to use. The magnets used in this case are common neodym magnets (ebay-Link) in disk shape. The diameter of is 10mm and they are 5mm thick. Nice to know: With magnets of this shape, you get the most magnetic strength, if the diameter is about as double as the thickness.
The final tight fit ensures a short thick mandrel (20° narrowing) and the screwed side-parts of the base part. With simple tilting of the printhead, you can easily break the magnetic force and the printhead comes free.
This quick change system offers an additional possibility: a simpel integration of a direct-extruder.
The Bowden system has advantages that come with the low weight of the printhead, but highly flexible filaments like 'Filaflex' oder 'Ninjaflex' are way to soft to get printed successfully with a Bowden. In combination with a lightweight, only 20mm long NEMA17 stepper motor and the E3D-Titan extruder, the whole setup weighs just 300g.
And with a direct-extruder like this you can print such flexible Benchys with ease: