Ninjaflex - anyone?

Hi,

I received a sample of Ninjaflex filament. Does anyone have any experience with that material on a Mendel90 (Nophead kit)?

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MfG / Regards

Stefan

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Blog / Gallery / Wiki / Mendel90 kit since Sep 2013 from Nophead / Original Prusa I3 MK3 since Feb 2018 /
OpenScad Workshop: Kursdateien
Octoprint Patron since April 2016

Check the Google+ 3D Printing Community page. William Frick and Sanjay Mortimer have posted on this material recently and they both use Mendel90 machines.

Regards,
Neil Darlow

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I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.

Also +DanielBull [plus.googleapis.com]

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[www.hydraraptor.blogspot.com]

I have some Ninjaflex and I tried printing using an ABS profile using Kapton tape, it resulted in a squidgy mess but it did actually print something. Needless to say it was welded to the Kapton, it dissolves nicely in acetone though. My next attempt to print tyre always resulted in a clogged nozzle. As its soft its like it can't grip it well enough and even at 240c it clogged. A mate said he was printing it 270c. I've not had time to play with it since but great link I will give it go following Daniel's tips!

This may not be applicable to Ninjaflex as I know nothing about it but when printing with flexible PLA, I found that I had to go really s-l-o-w (circa 10mm/s if my memory serves me right) to get anything like a decent print. Might be worth experimenting with speed as well as temperature.

Alan

Hi,

this weekend I had time to play with it. Last year I got a 1m black sample and decided it's too few material to play with it. A few weeks ago I ordered a spool in red. On Saturday I hooked it up to my Mendel90.

Unfortunately I'm unable to create a skeinforge profile. I'll give you a spool of Ninjaflex if anybody can help me out here. So I tried to do it with the newest Slic3r (1.2.6 experimental). I mainly changed the temperature to 220°C, no retraction at any move and all speeds to 30mm/s.

This is my first and second try:




As you can see, the top layer has some problem, so I increased top and bottom layer to 3 - but there is still a problem. Next I tried to print a GoPro case for a colleague:




It came out a little stringy - but thats a reason not to retract at any move. I'll give it today to my colleague and I'm very curious if it will fit.

Next I wanted to print a bumper for my Nexus 4. And that was a failure. Two times:




As you can see, the 1st layer becomes thinner and thinner. At the end, no more plastics came out of the nozzle. Same happened while printing the little Android robot (sure I sliced it with the above profile). After cooling down the nozzle a little,I could remove the filament, re-fittet it and was able to start the next print:




This is a Filament color sample chip I'm printing for all of my materials.

So in general - it's working (sort of).

But what happened during the first layer when it's a large area to fill with? Does the heat go up into the black part of the J-Head? Should I have the fan always on?

Sticking to the bed was very good. I have it prepared with wood-glue-water solution for printing PLA. It works very good for NinjaFlex as well.

Any help out there?

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MfG / Regards

Stefan

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Blog / Gallery / Wiki / Mendel90 kit since Sep 2013 from Nophead / Original Prusa I3 MK3 since Feb 2018 /
OpenScad Workshop: Kursdateien
Octoprint Patron since April 2016

See [forums.reprap.org] and [plus.googleapis.com].

I have also heard that Filaflex is an easier to print alternative.

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[www.hydraraptor.blogspot.com]

Hi,

thank you very much Chris!

I changed the profile to allow retracts as Robert Wozniak suggests (10mm at 120mm/s ...) He also mentioned

Quote

Avoid large print areas with no retraction. If necessary add a feature to the design that will cause a retraction, or modify the g-code.

Since the most designs exist as .stl files, I can't add "features" to cause retractions. I do not know, what a slicer causes retractions anyways. So I think, the 2nd idea will work here.

Looking into the gcode there are absolute values used:

G92 E0
G1 E-10.00000 F7500.00000
G92 E0
G1 Z0.200 F7800.000
G1 X-42.417 Y0.000 F7800.000
G1 E10.10000 F7500.00000
G1 X-42.417 Y-60.002 E10.81857 F540.000
G1 X-42.398 Y-60.501 E10.82455
G1 X-42.297 Y-61.781 E10.83992
G1 X-42.141 Y-62.766 E10.85187

So it's not possible to insert a

G1 E-10.00000 F7500.00000
G1 E10.10000 F7500.00000

whenever I wanted to. At least I have to switch the mode to relative and back to absolute:

G91
G1 E-10.00000 F7500.00000
G1 E10.10000 F7500.00000
G90

Will that work? Does the value of E stay where it was?

Then I can try to insert the 4 lines every 10mm of extraction and see if that will work.

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MfG / Regards

Stefan

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Blog / Gallery / Wiki / Mendel90 kit since Sep 2013 from Nophead / Original Prusa I3 MK3 since Feb 2018 /
OpenScad Workshop: Kursdateien
Octoprint Patron since April 2016

I don't know. I don't use absolute E for this very reason. It's impossible to hand edit the gcode or pause the machine, load the extruder and resume.

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[www.hydraraptor.blogspot.com]

Hi,

I managed to get relative E values. I wrote an awk script which inserts the retract every 10mm of extrusion. I'll see if that will work.

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MfG / Regards

Stefan

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Blog / Gallery / Wiki / Mendel90 kit since Sep 2013 from Nophead / Original Prusa I3 MK3 since Feb 2018 /
OpenScad Workshop: Kursdateien
Octoprint Patron since April 2016

Hi,

additionally retracts did work better (a little). After 4/5 of the 1st layer the flow decreases again. The 1st layer lasts 50min and I think it has to do with the heat climbing up from the nozzle. So I'll try it again with the fan on from the beginning.

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MfG / Regards

Stefan

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Blog / Gallery / Wiki / Mendel90 kit since Sep 2013 from Nophead / Original Prusa I3 MK3 since Feb 2018 /
OpenScad Workshop: Kursdateien
Octoprint Patron since April 2016

Hi!

Much better with the fan on from the beginning. I got a good 1st layer. Unfortunately I had to stop the printer ... heading to my office and work.

I keep you informed.

Is anyone interested in my awk script which inserts the retracts?

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MfG / Regards

Stefan

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Blog / Gallery / Wiki / Mendel90 kit since Sep 2013 from Nophead / Original Prusa I3 MK3 since Feb 2018 /
OpenScad Workshop: Kursdateien
Octoprint Patron since April 2016

How do the extra retracts help? Normally one would want to minimise them.

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[www.hydraraptor.blogspot.com]

I can only repeat what others stated already:

Quote
Daniel Bull
One of the pieces of advice I saw quite often was "don't use retraction with NinjaFlex" accompanied by photos of really stringy prints from people that didn't use retraction. I can only think this is aimed at people with Bowden style extruders or something like that(?) because I cranked up the retraction both in distance and speed on my Mendel and got far better results. One of the issues is the squidginess of the NinjaFlex accompanied by the slightly higher heat means it tends to dribble. At the moment I'm running a 3mm retract (prime/suck) at 40mm/s and as you can see from the photo its achieving quite good results. I need to experiment and find out what the sensible limits on my Mendel are as faster and further seems to be the way to go.

More details here.

Quote
Sanjay Mortimer
Retraction should be aggressive and quite long. I usually use 0.5mm for PLA/ABS, for all the flex prints shown I used 1.5mm.

More Details here.

Quote
Robert Wozniak

• Use Retraction: This seems to be the main factor in getting good prints.
• I think that the difficulty with printing with flexible filaments is that they will kink up in the feed path between the hobbed gear and the hotend if you try to extrude too fast which allows the heat chamber to build, which caused the compression in the filament to increase.
• Once it starts to kink, unless you retract enough to undo the kink, you're done.
• The Coefficient of friction of the flexible Urethane filament is so high, that there's no chance to push it through.
• The filament just continues to kink more and more until the total volume is filled.
• I've retracted kinked filament, and observed 10 or 12 kinks in only 10 or 12 mm
• In Slic3r (Printer Settings / Extruder 1 / Retraction) I use the following settings: Retraction Length to 10mm, Speed to 125mm/sec, Extra Length on restart to 0.1mm, Minimum Travel after Retraction to 1mm

More details here.

It's too early for me to give my own experience. The only thing I can say is, it's getting better the more of the others tips and settings I use.

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MfG / Regards

Stefan

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Blog / Gallery / Wiki / Mendel90 kit since Sep 2013 from Nophead / Original Prusa I3 MK3 since Feb 2018 /
OpenScad Workshop: Kursdateien
Octoprint Patron since April 2016

Yes I always use retraction and all those posts seem to say crank it up, i.e. further and faster, which make sense for a rubbery filament.

What I don't understand is "I wrote an awk script which inserts the retract every 10mm of extrusion. " . You seem to be saying you add retracts where they aren't needed?

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[www.hydraraptor.blogspot.com]

Needed for what? For not oozing during travel. The slicer inserts retracts before a travel and a prime before the next extrusion.

Here we have additional needs:

Quote
Robert Wozniak

• Avoid large print areas with no retraction. If necessary add a feature to the design that will cause a retraction, or modify the g-code.

As I wrote a few posts above, I can't add any "feature" to the model to have more retracts. The 1st layer of this bumper has a large area (there are at least 3 bottom layers) and takes 50 minutes to print. And there isn't any retract. So I added retracts every 10mm of extrusion and it worked well this morning.

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MfG / Regards

Stefan

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Blog / Gallery / Wiki / Mendel90 kit since Sep 2013 from Nophead / Original Prusa I3 MK3 since Feb 2018 /
OpenScad Workshop: Kursdateien
Octoprint Patron since April 2016

Yes that is what I don't understand. How does a random retract in the middle of a solid area help? Normally they tend to cause jamming problems rather than the opposite.

Is is retracted long enough to allow the filament to cool down a bit?

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[www.hydraraptor.blogspot.com]

It's all above:

Quote

Length to 10mm, Speed to 125mm/sec, Extra Length on restart to 0.1mm, Minimum Travel after Retraction to 1mm

It's too early to give a conclusion. I change parameters, I insert retracts, I watch the results. Maybe it's a misinterpretation, I can't tell you, what's going on inside the hotend. Maybe it has to do with kinking and the retract works against it. Or it does a little cooling - I don't know.

I see where this discussion leads to - you want to go to the bottom of the whole problem, right? I'm not sure if I'm the right person to help you to investigate this in all it's deep, but I try to give you all my experience.

I'll try to print the complete bumper this afternoon. We'll see if it prints the other layers the same as the 1st one.

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MfG / Regards

Stefan

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Blog / Gallery / Wiki / Mendel90 kit since Sep 2013 from Nophead / Original Prusa I3 MK3 since Feb 2018 /
OpenScad Workshop: Kursdateien
Octoprint Patron since April 2016

Hi,

it worked. At least I had to decrease the velocity to 15 mm/s. I tried with 30 mm/s and 20 mm/s but that did not work.






The phone fits (to my taste not fit enough, but that's a designers problem) and the buttons are usable. I'll print a few objects more to see if the problems are all solved. The print time was almost 5h.

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MfG / Regards

Stefan

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Blog / Gallery / Wiki / Mendel90 kit since Sep 2013 from Nophead / Original Prusa I3 MK3 since Feb 2018 /
OpenScad Workshop: Kursdateien
Octoprint Patron since April 2016

Looks like you have added retracts in the overhangs, which cause the filament to fail to bridge.

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[www.hydraraptor.blogspot.com]

Quote
nophead
Looks like you have added retracts in the overhangs, which cause the filament to fail to bridge.

I don't know how one could do that. Do you? I insert a retract all 10mm after a move. Not in the middle of a move. I do not split any moves and insert the retract in between.

Bridging is difficult with such material.

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MfG / Regards

Stefan

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Blog / Gallery / Wiki / Mendel90 kit since Sep 2013 from Nophead / Original Prusa I3 MK3 since Feb 2018 /
OpenScad Workshop: Kursdateien
Octoprint Patron since April 2016