Ninjaflex print very stringy & holes in the models. Why?

[msmollin]

So I tried out what I would call a semi-advanced ninjaflex print, and am getting mediocre results. Lots of string, and holes in parts of the models. They're basically 10 parts of a long tube. See the attached S3D render (it's currently still printing).

What am I doing wrong? Here's the pertinent S3D settings:

ABS profile, Medium Quality
Extrusion Multiplier: 1.35 (changed from 0.98 default)
Extruder Temp: 250C
Bed Temp: 110C (stays on the entire time... maybe needs to be shut off?)
Default Printing Speed: 1500 mm/min (changed from 4800 default)
Printed straight to glass bed.


I noticed in insta's "Thread of Filaments that work on the M2" that the one ninjaflex profile that got posted had the extrusion multiplier down at 0.93... but I thought I wanted flow increased, not decreased? Or am I getting bitten again by the "Extrusion Multiplier is not what you think it is" issue...?

Once it gets done printing I'll post a picture. I can probably salvage it since the tubing is actually supposed to look a little beat up... but I haven't tried printing anything this hard either in Ninjaflex before. Frankly I'm concerned about doing another larger piece just because the blasted stuff is so expensive that I don't what it messing up on anything that needs more accuracy.

It could also just be in the print. The first 20-30 layers actually look pretty nice.

[insta]

The short answer is NinjaFlex hates you. It hates everybody.

sorry I don't have anything more useful to add

[msmollin]

No kidding, right? This stuff is terrible to print with.

[sprior]

For starters I would print those one at a time so you don't get string from the travel between parts.

[jimc]

in addition to what steve said, if your using s3d then spread those thing apart a bit, set up sequential printing so it only makes a half dozen or so hops between parts. in the end you only have a few blobs per part to razor knife off instead of a few hundred. i find that ninjaflex prints nice and clean but its the jumps that kill it and make the print look like poo. if you can keep the jumps from part to part or area to area to a minimum then your ok.

[ednisley]

but I thought I wanted flow increased, not decreased? Or am I getting bitten again by the "Extrusion Multiplier is not what you think it is" issue...?

The Extrusion Multiplier has exactly one function: tweaking the volume of plastic that comes out of the extruder to match what the slicer expects, so that the thread width equals the width the slicer uses. It's a fudge factor between the known volume of plastic going into the hot end and the known volume coming out.

Once that's set, the slicer can adjust the flow rate to accurately fill whatever space it needs based on the other settings for perimeters, infill, top-and-bottom layers, and so forth.

Although printing a thinwall calibration cube with Nijaflex sounds like a major challenge, that's how to get the proper Extrusion Multiplier... and then you can adjust the flow rates for the other layers with more confidence that they'll do what you want.

[msmollin]

Thanks all for the feedback. After doing some additional research and double-checking settings, the default ABS S3D profile only has infill set to 20%, which it seems is far too little. Reprinting at 85% infill has improved things significantly in addition to spacing things out and setting up sequential printing. It's still stringy, but far less than it was before, and the model is staying solid better. I am wondering if 250C extruder temp inside my IKEA enclosure is too high?

I really need to do a test cube with this stuff and dial in my extrusion multiplier correctly, but I am under the gun of a looming deadline so I just went with what was posted in the other thread and it seems to be working fairly well.

[msmollin]

Spoke too soon. While much improve, still having what appears to be delamination between layers issues. Thinking this is a "temperature is too high" problem. Thoughts?

[jimc]

na its not too high. i run hotter than that. how much are you retracting? you cant retract too much with it because after the jump it doesnt come out of the nozzle right away. my retraction is about .6-.8mm. it doesnt really do much of anything and you have strings and a blob at the start which need to be cut off when the print is done but atleast the surface doesnt have holes. if you line all your start points up then its not too bad to clean up your model in the end.