Filament Guide with Duster and Filament Runout Sensor

by stevehlau Nov 5, 2018
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I’m new to 3D printing, and just got a Prusa i3 MK3. Can you please explain, what is the value of a filament guide, and what exactly does the “duster” do? Also, about the filament runout sensor: just yesterday I had a print running and heard a warning beep. I found that the filament had broken, so the Prusa printer already provides a filament runout warning. So, what benefit does this runout sensor provide?

Please understand I’m asking these questions out of curiosity and to learn. It’s very cool that you’ve devised these modifications and are providing them to others.



SuzanK: I am still learning on 3D printing as well with my MK2. Filament guide to my understanding is to guide the filament to the extruder in a consistence force, so the filament is less likely to break while printing. Duster is to clean the filament before entering the extruder, so your nozzle is less likely to be jammed from a dusty filament. At last, you do not really need the filament runout sensor because you have a MK3. However, my MK2 does not have the sensor, so I integrate that to my design that work with my MK2.

Since English is not my native language, I hope you understand what I am talking about and I wished I covered all the questions that you have. Happy printing.


Thanks for your reply, Steve, and your English is just fine.

As I mentioned, the filament did break on a print after about 10 minutes, so the filament guide might be helpful.

I am sure it is going to help. Filament breakage issue include filament tangle up while feeding to the extruder, old brittle filament cause by humidity, and etc.

... which exact switch type did you use?

I am using Omron SS-5GL2 microswitch. Unfortunately, I use FreeCAD instead of Fusion360, so my CAD file is not going to help. However, you can use TinkerCAD to mesh mix the STL file to make it work. Let me know if you need further assistance.

Thx for the info. If can import your cad file in fusion360 if you are willing to share ;)

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great design - could you please provide the CAD files (I have fusion360) in order to change the mount for my frame - I have an thicker frame than the original prusa frame...

that would be great!