Replacement IR sensor holder and selector for i3 mk3s mmu2s

thingiverse

(190504: I have made further upgrades to the selector, please also see "De Luxe selector for prusa i3 mk3 MMU2s") With the mmu2s upgrade, filament movement is indirectly detected by sensing the idler movement using an IR sensor. However, the setup is not sensitive enough to reliably detect very flexible materials such as filaflex and ninjaflex. To solve this issue, I made a variant of the design. The features are: * even filaflex can be detected when entering the idler * the bowden tube is not surrounded by a tower anymore, making it easier to service the extruder. * the sensor cannot move around freely anymore, as it is locked in position by attaching the signal cable. * you can easily customize the tower height (column B3 in the freecad spreadsheet) I also added a space for a magnet (you likely got the magnet as a spare when upgrading to mmu2s from mk3 or mk3s) that improves the FINDA. The feature: * FINDA will be less sensitive to thin threads and "filament clouds". I do not like filament clouds in FINDA ruining my prints, not at all... These items are based on STL-files found at: https://github.com/prusa3d/Original-Prusa-i3/tree/MK3S and https://github.com/prusa3d/Original-Prusa-i3/tree/MMU2 under GNU2 license (please read the LICENSE file)