Watchout for the Conductive Graphene Filament from BlackMagic3D

We found that the 1.75 filament (GRPHN-175)
had a very uneven diameter going up to 1.85. The filament jams the inlet of the hotend requiring a total dismantling of the printerhead.

Quote
ThorsenRune
We found that the 1.75 filament (GRPHN-175)
had a very uneven diameter going up to 1.85. The filament jams the inlet of the hotend requiring a total dismantling of the printerhead.

Hi ThorsenRune,
I'm very curious.... please.. please.. please.. post more information about this filament.
any technical datasheet?

on my printers even 1.95 it's ok
threaded brass union and notched brass union to drill with 2.1

Dario

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Ormerod 187
Firmware Electronics: Duet 0.6
Firmware Version:1.18.1 (2017-04-07)
Web Interface Version:1.15a
Slic3r 1.2.9a and Simplify3D 4.0.0
[www.dropbox.com]

I thought that all of the hot end parts had 2.0mm clearance,

The bowden is 2mm ID
The brass unions on the bowden should be 2mm ID even though the bowden is somewhat compressed, you drill it out with a 2mm drill bit (which probably makes it a bit larger than 2mm) during assembly,
The top part of the nozzle is 3mm and goes down to 2mm, then down to the nozzle diameter. And the PETF insert in the top of the nozzle brings the 3mm section down to 2mm.
So any jam from too large of a diameter I would expect to happen at the start of the bowden tube.

I don't doubt that you've had this issue, but it's probably for a different reason.... maybe it's because your slicer was expecting 1.75mm diameter, and thus tried to over extrude somehow jamming....

Or possibly there's too large of graphite particles in the filament, and that jammed it?

Hard to know without more details.


Regardless any filament that's +/- 0.1mm (5.7%) can be difficult to work with, because you'll randomly be under and over extruding. Personally I'd avoid anything with that much variation.

I haven't tried any conductive filaments, but I've heard of another one made by ProtoPasta, I wonder if it has the same issues.

Edited 1 time(s). Last edit at 05/12/2015 01:01PM by shadow651.

The only conductive filament I tried had extremely poor layer bonding, making the printed part very weak.

Dave

I must say that the company has been very responsive to this issue and has promised to send replacement material.
I did some measurements yesterday with an electronic caliper, revealing lumps on 1.95 diam. Second time it happened immediately while trying some very slow manual extrusion so its not a slicing problem at this moment. The filament gets stuck in the inlet, and it was not even possible to retract. Only way to get it out is a complete dismantling and cleaning the nozzle. We repeated with another reel with the same result. The filament seems to release some grains, which could be another reason for the jamming. As soon as we get the new material I will follow up on this.

Quote
shadow651
you drill it out with a 2mm drill bit (which probably makes it a bit larger than 2mm) during assembly,

I guess this is a very delicate proces which requires special drill and a mounting in a high quality bench drill?

Quote
ThorsenRune

Quote
shadow651
you drill it out with a 2mm drill bit (which probably makes it a bit larger than 2mm) during assembly,

I guess this is a very delicate proces which requires special drill and a mounting in a high quality bench drill?

I'm "working from home" ... no high quality drill or machinery!
Sure mine it's a bit larger than 2.1 mm but working fine

Dario

---

Ormerod 187
Firmware Electronics: Duet 0.6
Firmware Version:1.18.1 (2017-04-07)
Web Interface Version:1.15a
Slic3r 1.2.9a and Simplify3D 4.0.0
[www.dropbox.com]

Hello Everyone.
I am glad to see some feedback about this filament. I am currently testing with one spool of this BlackMagic3D filament.
I use a nozzle with 0.4mm diameter in brass, an E3D Online-like Direct HotEnd (no PTFE nor PEEK), and a gear drive right above the entry of the HotEnd.
My first experiments with BlackMagic3D allowed me to successfully print flat patterns (single extrusion, directly on plate), with volume resistivity as low as 10 Ohm.cm.
However when iddle, the filament swells and kind of solidifies in the nozzle and cannot be extruded whatever the pressure applied. I had to remove the filament from above, cut the tip which had swelled, and put the filament back again.
Besides, my second series of experiments was a complete failure. I could not extrudate the filament at all, except when just introduced and pushed by hands. Higher temperatures could not help either... I also had to completely dismantle the printerhead, and still, as the filament is brittle, it broke in a part not heated. I might have to burn it with a torch, or just buy a new heatbreak (planning both in parallel).
I have no tool to check the diameter, but it is true it seems larger than 1.75mm and quite uneven. This is probably why I have trouble to insert the filament, and also why it gets stuck in the nozzle.
I kept the spool within the cartridge of my 3D printer, which has no control over the environment (temperature, humidity, undesired particles floating around...). So I suspect some kind of aging of the filament: oxidation, water absorption,... which might also lead to change in filament diameter (?). What do you think? I have to look into it, but so far I found no particularly strict recommendation from the supplier about the conditioning of the spool except "dry environment".
I have read on the website of Graphene3DLab that a nozzle with diameter larger than 0.5mm is recommended, which might help. I am considering ordering one from my 3D printer supplier.
What about using a nozzle in steel instead of brass? Have you tried?

Florian

Edited 1 time(s). Last edit at 05/13/2015 04:34AM by cimballi.

Quote
cimballi
... with volume resistivity as low as 10 Ohm.cm.

Wow that is low! My conductive filament (not graphene) is well over a megaohm per square and used only to dissipate static.

Dave

Quote
ThorsenRune

Quote
shadow651
you drill it out with a 2mm drill bit (which probably makes it a bit larger than 2mm) during assembly,

I guess this is a very delicate proces which requires special drill and a mounting in a high quality bench drill?

It's a step in RepRapPro's instructions, you're only removing the Bowden tube that got compressed by the brass couplers. If you don't do this you can have problems with the filament not fitting through the Bowden tube.
[reprappro.com]

If you're in the U.S. it can take a bit of work to get a 2mm drill bit, but other then that it's not difficult.

I bought 2mm drill bits as part of an inexpensive set at my local Harbor Freight. They don't have full metric sets, but they do have "mini" sets with 2mm for a few dollars. Hope that helps!

Update: The support team sent me two new reels, saying "we had tested diameter (1.75) and printability (we made some extra filament on the end of the spools to do test printing) before sending, both were fine)". The ones received here in Europe were thicker, measured with a digital caliper. For the first 1 meter we found that the minimum diamenter was 1.86mm and the maximum was 1.94. (Before anyone claim that I do not know how to use a caliper let me add that a collegue confirmed the readings. Furthermore measuring standard PLA with the same process gave consistent 1.75-1.80mm readings.)

Only explanation for now is that there must be some black magic happening during shipping, or the americans have devalued the meter by 10% . ;-)

Thanks for the hints about drilling extrusion, we will try that when we got time.
Also thanks to cimballi, we had same experience, so I think its essential to process with an immediate retraction whenever there is no extrusion.
Or worded differently: the 'spice must flow' (F. Herbert: Dune)
However resistence is to high for our intended use as printed wires.
Our principal interrest was to print electrodes for a neuroprothesis (http://mecfes.wikispaces.com/en) but it seems that there is a problem with biocompatibility.
Do anybody have some information as to this regard?

Edited 1 time(s). Last edit at 05/25/2015 08:41AM by ThorsenRune.

Slightly thicker should work OK so long as it's reasonably consistent. Just adjust the extrusion factor slightly. I usually need a slight tweak of the extrusion factor for different reels if I want a perfect print (but a single setting is usually good enough for most jobs).

Dave