Printing with Flexible Filaments

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When it comes to Exotic Filaments Flexible Filaments hold a special place in the hearts of many 3D printers.

These flexible thermoplastic polyurethane (TPU) filaments let you 3d print squishy toys, RC car wheels, and other practical pieces. The main appeal of flexible materials is the ability to print non-ridged items. The new Lulzbot Taz 6 has NinjaFlex washers in it, and there are plenty of files for cell phone cases that are designed for flexible materials. For this review I’ll cover 3D printing with NinjaFlex and SemiFlex from NinjaTek.

Flexible Filaments NinjaFlex

I have wanted to 3D print with NinjaFlex for a while, and I have been gearing up by assembling a Flexystruder. I spent about a week trying to get my homemade Flexystruder to work before I gave up and went for broke.

It turns out that you do not need a Flexystruder to print flexible material on a Lulzbot Taz 5!

standard tool head - Flexible Filaments
NinjaFlex printed through a standard tool head

When I went to the Lulzbot factory , I spent some serious money on the problematic dual extruder and a spool of NinjaFlex and SemiFlex.

I have heard mixed reactions to flexible materials in social media, but for me this was a solid material to print with.

When I gave up on the Flexystruder I decided to test the NinjaFlex first by printing a bangle for a friend.

The results were amazing. I just had to tighten the tension on the idler arm to secure the filament in the tool head against the hobbed bolt.

On my first print the NinjaFlex printed smoothly through the standard Lulzbot tool head. The filament stuck perfectly to the blue painters tape, and the bangle printed perfectly the first time!

Flexible Filaments
flexible bangle

NinjaFlex is a one of the most flexible filaments on the market. I was able to tie a knot in it, untie it and still be able to print with it. That is something a ridged filaments like ABS or PLA simply can’t match.

Flexible Filaments SemiFlex

Printing the same bangle in the more ridged SemiFlex had a hiccup the first print. About half way though there was a jam. It turns out some of the filament had popped out of the extruder and kinked just below the hobbed bolt of the extruder. To fix this, I took a secion of discarded filament and put it into that space.

Combined with a filament oiler, the SemiFlex has also escaped the initial hiccup to become another solid filament.

Flexible Filaments
semiflex printed

My only complaint is that when I print multiple pieces, there is a lot of stringing that I have not been able to reduce.

Both NinjaFlex and SemiFlex have quickly become a favorite material to 3D print with. In the short time I’ve had to print with them, they have booth had solid printing performance with minimal hassle. The stringing that happens between multiple items is something that I’ll have to work on.

Using my filament ranking system I’ll score the TPU filaments as the following.

Flexibility: They can bend into a tight knot and still be 3D printable. 12 points

Color: Solid color from start to finish, with a glossy sheen when printed. 3 points

Starting quality: Sticks perfectly to blue painters tape. 2 points

Warping: No warping. 3 points

End of print: Both come clean off the build plate. 3 points

Enviromental: No noticeable smell at 230 Degrees C though any higher will give off a burnt tire smell. 2 points

Special Considerations: You may have to run your print slower to achieve desired results, and some printers may not like the higher friction coefficient of this filament in a feed tube, so read your 3D printers instructions for recommendations for printing with TPU. LulzBot may want to check their claim that you need the separate flexystruder to print with this material. 1 point

Finishing: You can use wire cutters to remove strings, but this material is chemically resistant to many solvents. This is great for automotive parts, but does limit how it can be processed. 1 point


Both NinjaFlex and SemiFlex Score 27 / 28

This week 3D-PT will attend the National Autism Society of America Conference  in New Orleans, and I will blog about my experience 3D printing for people with Autism

DISCLAIMER: NinjaTek did not provided samples for this review. I purchased them at my own expense.

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  1. Juan Solis says

    The quality of that NinjaFlex print seems really impressive, especially considering that flexible filaments tend to be very problematic and that one got it right at the first try.

    1. Stan Baldwin says

      I can see where flexible filaments may give printers some troubles, but a little research and planning can take care of 90% of that. NinjaFelx does print very hot but smooth like butter, and I had fun making flexible prints with it.

  2. Richard Bynum says

    The bangle looked great!! And SO flexible!! It sounds easy to work with, by what you wrote in here. Why did they say you needed a Flexystruder? I want to make some flexible stuff!! I would love to make some tires for my gas R/C buggy to go across water…Or try to go across the water..haha. And I would like to print out a soft flexible guard for the sides of my wheelchair. I can’t wait to try this filament out!

    1. Stan Baldwin says

      In theory flexible filament bends too much to go through a standard extruder, and the flexiextruder is designed to contain the filament as it goes through. I just stuck a piece of filament in the small gap in the extruder (pics to follow soon) to keep it from ooozing out. I’m puting flex through the MOAR right now, so I’ll let you know how that goes.
      I think lulzbot is gust trying to sell another tool head on this one. I love how TPU prints most of the time (stringing is an issue) but its great to play with!

  3. Tom Baxter says

    The only flexible filament I’ve tried so far was NinjaFlex, but once I got my settings dialed in, it was awesome. I actually printed out the “Cat” and it’s like a stress toy. I also used the Ninjaflex to print am replacement tip for my Daughter’s crutches. I made it about 80% infill and it was very tough. I have a picture of it in my gallery that I posted in the forums if anyone is interested.

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