Smallest Motion(Smart) Filament sensor mk2

For now it seems working, future changes on demand/result of long term testing.

6.4.2022
replaced by https://www.thingiverse.com/thing:5342918
5.3.2022
It wil grind through hole and starts slipping in about 100m of PLA. You may try ptfe from both sides or use nylon on body, but I currently working on 3 bearing versión.
3.3.2022
aditional distance of axis
28 tooths encoder instead of 30 (precision 0,45 -> 0.9 in Marlin)
filament hole 0.1mm closer to axis
PTFE ends before wheel, option add/remove PTFE to both sides - you can have wires to left instead to right

28.2.2022 - fine tunning - added 0,2mm between axis and sensor - I was getting false alarms, tooth encoder base partly covered sensor

28.2.2022 - first mk2 version, currently in testing

resolution < 0.5 - you can use 1mm setting in Marlin FW motion sensor section
accurate - can detect missed full step.

If you get random filament runouts during print, than you have step skip or filament slip at extruder normaly unoticable, I have to increase current from 400mA to 470mA on my extruder to have successful 130mm/s / 1mm runout distance print.

you will need:
- ir pusa filament sensor (without accessories) - i have 0.1 vesion only, let me know, if 0.4 can be fit
- mk8 extruder drive gear http://www.na3d.eu/p/2421/toothed-feed-wheel-mk8 - but sensor is customizable, any with diameter < 10mm will most likely work after customisation.
- M3x30(25) screw for axis (+ nylon nut, but works even without it)
- M3x20 screw + nut

Encoder wheel can't be printed in prusa slicer. Use ultimaker cura (engine) for slicing it successfully. You must have perfect first layer for print it succesffuly - you can't use elephant foot compensation - z babystep / z-probe distance setting will be probably necessary. I use PLA for it.

You can print rest parts with anything, if you get elephant foot on iddler holder of titan extruder, you must cleanup axis hole. I didn't touch filament PTFE holder on it, 4mm drill is necessary. Holder must be printed with supports in iddler area.

With 30tooths and 13mm diameter of encoder you must go under 8.5mm diameter on filament grove to archive 1mm marlin accuracy. But you can enlarge and/or add tooth to encoder as long as cura is able to slice tooths and you manage to print holes between them.

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