NinjaFlex help needed

Hi everyone. I’m having some serious issues printing with ninjaflex. I’m not new to this filament, and have successfully printed quite a bit with it, but recently I’ve had consistent failures with some files I’ve been working with. They’re meant to be prints of leg muscles and I’ve tested them all in meshmixer to assure they’re okay for printing.

I’m printing on a TAZ6 / Flexystruder v2 using legacy Cura, and the default ninjaflex profile.

I’ve successfully printed both of the files I’m trying to print before, but I didn’t note down the settings I used. (Though I don’t think I changed anything from the default Cura ninjaflex profile.) I managed to get something like this:

Now I’m consistently getting this as a result:

I get a few okay lines but the printer just seems to give up partway through and everything gets fuzzy.

I’ve tried both the default Cura settings and these tweaked settings, based on research I did, both with unsuccessful results:
Layer height 0.3 (I’ve also tried 0.2)
Shell: 1.2
Retraction: On, 1.5 (I’ve also tried turning retraction off)
Infill: 70-75%
Print Speed: 14
Print Temp: 220
Bed Temp: 40 (w/gluestick)
Supports: Everywhere, Lines, 17% (I’ve also tried denser support infill)
I’ve also tried the flow rate at 100 and 145.

I’m not sure what I’m doing wrong. It seems to be something with the supports. I printed out a small, completely flat test file using the same roll and settings, and it came out perfectly. I’ve also tried switching out rolls and am having the same trouble.

These are how the supports looked on the other successful print, but I cannot get these to replicate.

Does anyone have any advice for what might be happening here?


Can’t really tell the orientation of the object… is the stringiness the top of the object? It looks like after a while the nozzle is starved of filament. So it could be heat creep or something to with the filament getting stuck in the extruder after a period of heat.

Can’t remember if the flexystruder 2 has the thumbscrew on the side to increase pressure against the hobbed bolt. If so, give that a half turn… or full turn.

A while back people used to “season” the nozzle when printing PLA. Basically it would stick to the sides of the hotend. So people would dip the tip of the filament in cooking oil before feeding into the hotend. The oil lubricates and allows the filament to pass better. This could work for you… YMMV, I’ve never tried it.

As kcchen_00 suggested this appears to be an issue of heat creep. A good first step to help reduce heat creep is to verify the microblower is turning on, it should come on as soon as the printer is powered on. If that checks out you can reduce your print temperature slightly, 5 degrees to start. The profiles on Cura are sometimes going to need adjustments based on the color of filament being used as well as the ambient conditions of the print area (eg. room temperaure).

It’s definitely on the top. It seems to print fine at first, the infill looks quite nice, and then it starts to get stringy as it goes up. I’ll take a look and see if I can tighten the thumbscrew on it, and look more into potentially ‘seasoning’ the nozzle and if that’ll work with NinjaFlex. Thank you so much for your reply!

I think the microblower is turning on, but I’ll double check that to be sure. And I hadn’t thought about heat creep in the flexystruder. I’ve struggled with that before when printing PLA, so that definitely might be an issue here too. I’ll try printing it a bit cooler and see what happens. Thank you! I’m still learning and your advice is really appreciated. :slight_smile:

I’m using an Aerostruder for Ninjaflex, so take my suggestions with a grain of salt. I set the retraction to 2mm. You might give that a try to see if it helps. Bed temperatures and fan speeds are especially important with the Aerostruder, but I don’t know if that is also the case with the Flexystruder. With the Aerostruder, the bed temperature needs to be at least 50C and the fan speed at a maximum of 30% in order to avoid thermal runaway shutdown at the beginning of the print when the airflow bounces off the bed and cools the thermistor too much, causing more power to be sent to the hot end heater.

Feel the aluminum plate right above the blower and see if it feels more than just warm, and if so your blower is failing to cool enough.

I do not recommend trying oil.

How has the Aerostruder been doing for you with Ninjaflex, if you don’t mind me asking? I’m looking into possibly exploring some of the newer toolheads, and one that can print both hard and flexible materials would really be useful as I switch out between them regularly.

Thanks for your advice as well. I’m looking into the retraction setting to see if that’ll make a difference. :slight_smile:

I’ll throw in my experience – as being able to switch materials was exactly what interested me in the Aerostruder.

I’ve gotten excellent prints from the Aerostruder with everything I’ve tried (ABS, PETG, PCTPE, Alloy910, Ngen, Cheetah, and Ninjaflex. It is GREAT to be able to switch between Ninjaflex and hard filament without swapping toolheads and re-flashing firmware every time.

I’ve had two issues with the Aerostruder – neither big enough to offset the benefits.

  1. Some filament grinding on one print where I was using thick layer height and fast, dense infill along with retraction – seemed like it just couldn’t keep up melting the filament as fast as the Hexagon could (unsure why; same wattage heater, maybe smaller melt chamber?). Resolved by slowing down the print and limiting retraction, or reducing layer height a bit.
  2. Filament jams when trying to remove filament. Due to the E3D’s filament tube, any small “bulge” from the melt chamber can easily get stuck when trying to remove filament. Pull harder thinking it will come through, and it may get jammed to the point of requiring disassembly (guess how I learned that, lol). Best advice here, heat filament to full melt temp and then slowly and steadily retract it – don’t try to pull it out fast, or at soften temp. If it resists, don’t pull harder – instead feed it back in and extrude a few mm, then try another slow and steady retraction to remove it.

Only other annoyance is nozzle visibility. With the Hexagon, it was really easy to see the nozzle and watch the first layer being laid down, right as the filament exited the nozzle. The Aero’s fan shroud and nozzle location make that pretty difficult, particularly on small parts.

None of that is meant as criticism, just things of which to be aware. It prints well, I’ve seen some better bridging and overhang performance due to the fan/shroud design, and the ability to print flexibles without changing toolheads is fantastic.

I’m getting excellent results with Ninjaflex using the Aerostruder on the TAZ 6. In fact, my flex prints look as good as my best PLA prints – really nice!
Keep the speed low and start with a 50 to 60C bed and NO FAN for the first few millimeters of layers, and a maximum fan rate of 30%. If the fan starts too soon, it over-cools the thermistor, so it thinks the hot end is too cold and applies more power resulting in a thermal runaway error and the print halts. The cool air apparently bounces off the bed to the thermitor when printing the lowest layers, so less fan and more bed heat stops the thermal runaway. As the print continues on to the higher layers, the fan speed and bed temp become less of an issue.

Fabulous! Thank you both, ScottW and tetralite. It does get to be a pain to switch back and forth and flash the firmware. I tend to find that takes up a good portion of my set-up time when printing, and having them both in one would save me a lot of time. At the moment I try to avoid changing out toolheads until I absolutely have to. I’ll definitely be looking into the Aerostruder after your feedback.

Slow print speed is also important. I’m using 15mm/s for the first layer and outer walls and nothing over 20mm/s for anything else. And I’ve been getting even better results by upping the retraction setting to 5 to eliminate the stringing between multiple parts. 215 to 220 seems to work better than 225º. At 225 the surfaces don’t look so good – I think it is some kind of stringing effect on the surfaces – “micro-stringing”?

@tetralite - What retraction speed are you using? The Lulzbot cura profiles have retraction speed down at 4mm/s, which adds a noticeable pause/delay for even a 2mm retraction. I bumped it up a bit, but wondering what speed is working for you.

@tetralite I had to up the retraction distance some on my prints, as I was getting really bad stringing during travel. The speed I have set to the default of 4mm, and that seems to work okay. For me the key was setting my travel speed to 200mm/s. That seems to have pretty much gotten rid of the spiderwebs I was getting all over the bed.

I’d like to thank everyone who dropped in to help me. From all your suggestions and guidance I’ve gotten my prints looking good again. I did have another question, and hopefully this is the right place for it. While my prints are looking good, I’m having trouble with the supports now. They print fine, but they seem overly stuck to the part, to the point where it’s leaving grooves where they’re removed.

The lines on the left side are where I removed the supports and they are grooved in, as if the supports were almost pushed into the part.

Right now I’m printing using the Lines setting, with support density at 17%. I’ve tried setting the Z Distance anywhere between 0.3 and 0.6, as I’ve heard increasing that can help with support removal, but it doesn’t seem to have made a difference.

Has anyone had this problem before?

Here’s a Cura profile I’m using to print NinjaFlex on a Taz 6 with the Aerostruder. This profile, as is, has no infill, but I have used the same profile with an infill, and changing the infill setting doesn’t affect the final quality, so if you need infill it’s no problem. Don’t expect to get good quality at high speed with NinjaFlex. I have surrendered myself to letting it be a slower process than printing PLA and ABS. This profile may leave extremely fine strings between parts when printing multiple parts. These strings are so fine they can be mostly scraped off with a fingernail. A hit from a heat gun also works. I have further resigned myself to printing one NinjaFlex part at a time when possible to avoid having to deal with stringing at all.

Profile generated in Cura 2.6.66
for Taz 6 with Aerostruder: (716 Bytes)

I’m using a retraction amount of 4mm and retraction speed of 6mm/s. Don’t know if it makes much difference between speeds of 4mm/s and 6mm/s.
I haven’t tried different travel speed yet – mine is still at 175mm/s, and I found that the greater retraction amount and lower temperature practically eliminated stringing. I still get real fine strings that can be scraped off with a fingernail.