Mk3S MMU2s Long Arm IR sensor

thingiverse

This was a learning project and I got a lot out of it, however now I use The Zero Beast's extruder which is basically all around better. He's got some excellent firmware as well. Check it all out at https://www.prusaprinters.org/prints/7690-tzb-mk3smk25smmu2s-extruder-mmu2s-no-tower-v2, it's highly recommended. For other Prusa MMU stuff: https://www.thingiverse.com/AbeFM/collections/abes-mmu2-stuff. --------------------------------------- NOTE: WIP! I'm using this with some success but that does not mean it's bulletproof. I'd seen a couple projects which answered issues I was having - mainly that sometimes: 1) I need to recalibrate the IR flag to fine tune it 2) Soft filaments don't move the idler much (~1/8mm) 3) It's hard to adjust! So I came up with this based loosely on two great projects: https://www.thingiverse.com/thing:3740480 - Screw-adjustable IR sensor flag, https://www.thingiverse.com/thing:3554066 - High Motion Ratio "Tall Flag". The tall flag was a little weak and a little hard to print. I broke mine and ran it for months glued together. There's a remix now which might have it work better but it was a little in the way although conceptually pure. The screw adjustable set up had a direct adjustment (limited by screw pitch) which I thought was a bigger concern than it really is. Still, coarse adjustments required moving the whole chimney. So I decided tipping the chimney so it rests in front of the X-axis motor instead of standing up would give me more room. I have ~2.5:1 gain, so my 1/8th mm deflection becomes nearly 400 microns. Still a small distance but much more compatible with the sensor PR used. For solid filaments the deflection is more substantial, ~4.5 mm. I found the slop in the door to be extreme, I drilled out the hole with a #22 drill bit (~4.05mm), slipped in a short length of 3mm ID/4MM OD PTFE as a bushing and it controls the door much tighter. This may help to limit noise with small defections.