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IR Sensor Parts Upgrade  

Eminent Member
IR Sensor Parts Upgrade

A few weeks ago, I finally got around to installing the MMU2S, MK3S upgrades to my MK3 about 9 months after receiving,. First thoughts are "I used to enjoy 3D Printing and my MK3". My second thought is "This design was not ready for production!". 

Has anyone had any luck with alternate extruder parts or top housing parts? My IR sensor assembly keeps coming loose from the extruder. I have had way more failed single color prints than successful over the last few weeks and gave up on multi color until I can get it to print a single color reliably and consistently. 

I feel like I am several months behind the curve so any help catching up would be appreciated. 

NOTE: Not sure if this should be here or under the MK3S forum.

This topic was modified 2 years ago by theycallmejohn
Posted : 22/10/2019 11:34 pm
Noble Member
RE: IR Sensor Parts Upgrade
Posted by: @theycallmejohn

... My IR sensor assembly keeps coming loose from the extruder...

Which part exactly? There is no force applied to the top cover (the top hat). Once fixed, it should stay in place.

I know it requires a lot of patience to calibrate/adjust the IR sensor but I haven't seen any better solutions so far. (And I would like to see it as-well)

Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram...
Posted : 22/10/2019 11:57 pm
Estimable Member
RE: IR Sensor Parts Upgrade

Since the first time I look at the MK3S-MMU2 IR sensor chimney assembly, I thought it was a poor design, only one screw realy ensures the tightening of the chimney, the screw that passes through the filament cover to the extruder body, the second one is just bolted to the filament cover and does not prevent the assembly from moving.

I designed my own extruder assembly and use it from a long time with great success. and a remix of my chimney  

I added a second tensioner screw, but it works also with the original single tensioner.

Here an other design with no chimney

This post was modified 2 years ago by ad.lamy
Posted : 23/10/2019 5:20 am
Active Member
RE: IR Sensor Parts Upgrade


I am using the first two mods mentioned and they work great.

Posted : 26/10/2019 5:38 am
New Member
RE: IR Sensor Parts Upgrade

I just did the Mk3S+ MMU2S upgrade.

Working smoothly now, BUT there are 2 parts to IR sensor calibration.


You must physically align the filament path through the fitting into the orange piece that replaces the piece holding the steel ball.  This is a high precision pathway and the precision exceeds the printing tolerances for the parts.  I started by using 2-3 different size small diameter drill bits to basically deburr and bring the filament pathway into circular alignment.  I also chamfered the top opening of the filament pathway for the orange part (that used to hold the steel ball).  Then you put the top on and partially secure the screws.  Now insert filament and rotate the top cover slightly until the filament path is completely aligned and there is no friction to the filament path.


Follow the standard procedure to calibrate the IR sensor...however, don't undo STEP ONE above.

Once both calibrations are done things work much smoother.

Posted : 05/01/2021 9:21 pm
Eminent Member
RE: IR Sensor Parts Upgrade


pictures would be great... I'm just starting the mk3s+ mmu2s upgrade

Posted : 08/01/2021 7:05 pm