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Prusa Mk3S + MMU2S ir sensor + idler  

New Member
Prusa Mk3S + MMU2S ir sensor + idler

I had to print my extruder idler again.

I used Esun black petg.

The idler itself is fine, but when I put it in between the IR sensor, it does not trigger the sensor.

Now, if I put anything else between the IR sensor, it works fine. If I put a piece of paper, it will trigger, if I put a nylon clamp, it will trigger, but if I put the ilder, it will not.

It's like the infra red is going through the idler, which makes no sense to me.

Do you guys think it could be somehow related to the material?

The idler was printed with an infill of 30%

I unassembled the IR sensor and fitted the idler manually to ensure it was perfectly in between the IR sensor, and even then, it was not triggering the sensor.

thanks in advance,
Otávio Ribeiro

This topic was modified 1 year ago by otavio.r
Posted : 12/09/2022 12:45 pm
New Member
Topic starter answered:
RE: Prusa Mk3S + MMU2S ir sensor + idler

I printed the same extruder idler, with the same config, but using an orange esun petg, and it works perfectly.

Odd... probably something with the esun black petg.

Otávio Ribeiro

Posted : 12/09/2022 10:26 pm
Eminent Member

Honestly, I had nothing but problems in tuning my extruder idler (MMU2 version) before switching to this:

I believe you should already have the necessary extra small screw and that's it. By adjusting the small screw, you can fine tune it just so that everything starts working again.

The original idea of moving the whole tower is just horrible.

This post was modified 1 year ago by waino
Posted : 26/09/2022 7:42 pm
Honorable Member
RE: Prusa Mk3S + MMU2S ir sensor + idler

Black can be made different ways.  I notice that the Taulman PCTPE “Black’ seems to be a really dark blue.  You mention that it seems that IR passes right through it.  If they make the black PETG with organic pigments ( or a blend to make a black) they will be IR transmitting.  Carbon black pigment will absorb and block IR.

Orange is probably a blend of organic and some white, which would provide enough IR scattering to make it IR opaque.

Posted : 31/10/2022 12:50 am