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UM3, Blackmagic conductive material grinding.

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I am trying to dual print on a UM3 with the second material being Blackmagic3D's conductive graphene filament (3mm). My prints will dual extrude properly about half way though the print then the graphene will suddenly stop extruding, no splurting or reduced flow, it just stops. This tells me that it is clogging in the nozzle. When it does, the feed grinds the filament to nothing.

I have tried increasing the temperature a small amount (225c from 220c recommended printing temp) with a little improvement. I am not sure how high I can take this filament and I don't currently have enough to do 10 test prints, can anyone make any recommendations?

Also, my UM3 is stock, with 0.4mm tips. Blackmagic3D recommends 0.5mm tips, but I am unsure what is involved in changing the tip sizes. Does it require changing settings in Cura, buying a new print core, or is it as simple as swapping the nozzles?


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Standard Cores don't allow the user to swap the nozzles. You could buy a 3dsolex unofficial core that allows different nozzle sizes. Or you could buy a precision 0.5 drill bit and make the nozzle hole bigger. After doing a or b to adjust the nozzle size on Cura you can do it on the advanced mode changing the line width (unhidde also the other sub options that cura hides by default).

Ofc maybe it isn't a clog, and just the feeder that grinds the filament to the point of not being able to push it. You might want to try to relax the spring tension (it has a screw on the top that moves the lever indicator up/down, up is relaxed, down is more tension). That and printing with less retractions might be enough to keep printing.

On the long term if that's your main material I would seriously consider using a better feeder like a @bondtech

I don't know if @bondtech has developed any tool to make easier for the um3 users to upgrade? Atm changing the feeder requires the user to use ssh (to access the machine remotely) and a bit of knowhow to edit the firmware files.

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I think all @neotko advice is right, but not necessary to the 3D Solex upgrade; here is what I think is your problem:

The bowden tube in combination with your filament. Please, take part of the filament which you have already run through the feeder, ie tied to print with and manually run it through the bowden.

Like this:

1) turn off printer

2) Lift the "filament release" on feeder (this is quite hard!)

3) Pull out all filament while holding this release knob

4) remove bowden clips back and front

5) push insert holding bowden down, and while holding down pull out bowden

6) manually push filament which you already tried to print (very important, to diagnose what neotko says about filament grinding and more...)- through the tube.

Should go light.

7) report back, and we will help you!

To put back bowden, insert and make sure it is in very bottom, there may be some "edges" to overcome.

, while holding bowden down, lift insert with a blunt knife and insert clip.

Insert filament while lifting knob on feeder and feed it manually all the way to the front.

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I see the filament that you are using is 3.00mm. UM3 is designed for 2.85mm filament.


This might explain your grinding problems.

Have you checked whether or not the filament is abrasive? Beware that there is a brass nozzle in your print cores. It will quickly wear out. Wear resistant print cores are not (yet?) available.

Edited by Guest

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