Meet the Flexibles | SD3D Printing
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Along with the other Unique Filaments we have reviewed thus far, we have been recently working very closely with flexible materials for FDM 3D printing.  Each has benefits, and each have their own softness and flexibility.  Today we will be looking at PCTPE from taulman 3d, FlexSolid from MadeSolid, NinjaFlex by Ninjatek, and the new Cheetah by Ninjatek.  Along with overall properties, we will be giving printing settings and even a Cura profile to download.

taulman3D
MadeSolid
Ninjatek

Please keep in mind that there more than these four flexible filaments available, but these are the four we have tested and like to use.  The settings discussed are all on our Lulzbot TAZ5 printers with e3D hotends.

PCTPE

 Strength: 5046 PSI, Elongation: 497.6%, Tg: 74C

PCTPE Octocat
PCTPE Bracelet
PCTPE phone case

 Properties:

PCTPE is an amazing material by taulman 3D which provides the flexibility of an elastomer with the durability of nylon. PCTPE stands for “Plasticized Copolyamide TPE” or a chemical co-polymer of highly flexible nylon and TPE (thermoplastic elastomer). The interlayer adhesion of PCTPE is excellent which is what makes this elastomer the most durable of any we have tested to date.

PCTPE While the elongation is nearly 500%, this is actually the least flexible of the 4 materials reviewed here.  As you can tell from the video to the right, there is definitely resistance to bending the bracelet in half.

With that said, the fact that PCTPE is a bit more stiff than the other 3 materials means that it allows for an easier printing process.  You can have normal retraction settings and print at a higher speed than the more flexible Ninjaflex and FlexSolid, since the filament will not curl up while feeding.

PCTPE PCTPE can be much more flexible when printed without much support or in a thin manner.  In fact, we have found the other flexible materials to be too flexible for things such as phone cases, which PCTPE actually works great for.

Since there is plenty of bend before breaking with PCTPE, but still rigid enough to maintain its shape, this material works great on any mechanical part that vibrates or requires cushioning.  PCTPE comes in a standard white color but can be dyed as any nylon based material can.

Print Settings:

As mentioned above, PCTPE is a fairly easy filament to print relative to other unique materials.  The one main issue arises with bed adhesion and warping.  Since PCTPE is a nylon based filament, it requires a coat of PVA be applied to a 45°C glass bed and will not stick to PEI.  We make a mixture of roughly 8 parts water to 1 part Elmer’s glue, paint on a thin layer, and wait until it dries before printing.  Even when doing this process you will still experience warping from time to time.

PCTPE prints at a fairly fast 45mm/s and does surprisingly well with overhangs.  As you can see below, the filament can handle up to 55° without requiring any support material.  This is especially good because since PCTPE has such a high layer adhesion it can often be quite difficult to remove support.

PCTPE OverhangWhen it comes to support settings,  we will set the angle required to right around 52° and only have a fill amount of 10%.  We then increase the distances for support from PLA to 0.8mm in the X/Y direction and 0.16mm in the Z axis.  This seems to work quite well, but complex models will still give you a tough time.

Due to the stiffness of this filament relative to other flexible materials, we can have normal retraction settings and prints with little to no cob web strings.  We have the minimum travel for retraction at 1.5mm, combing type to all, minimal extrusion before retracting at .005mm, the z hop when retracting to 0.1mm, the speed to 10mm/s, and the distance to 1.5mm.

A full profile for Cura a 0.4mm Nozzle with an e3D setup at .25mm layer heights .ini PCTPE can be downloaded HERE

Review:

PCTPE was the first flexible filament we enjoyed printing.  We instantly began printing phone cases, bracelets, other wearable items since it was so much smoother and softer than the average PLA or ABS.  This product is also great for parts that require brace impact or have a lot of vibrations since it holds its shape much better than the other three materials listed.   While it definitely has its applications, we seem to find ourselves using FlexSolid more frequently.

FlexSolid

 Strength: 7250 PSI, Elongation: 450%, Tg: 74C

FlexSolid Octocatt
FlexSolid Bracelet
flexsolid belts

Properties:

FlexSolid FlexSolid is an amazing elastomer from MadeSolid. It combines an incredibly high elongation to break and low durometer rating, making it one of the closest materials to rubber we have ever seen formulated for FDM printing.

While its elongation is less than PCTPE, it is clearly a softer and more flexible filament.  NinjaFlex may have more of a flex to it, but the surface quality on FlexSolid is superb while still being able to print at higher speeds.

flexsolid belts 2FlexSolid also seems to have a bit of a translucent look to it with no real ability to dye. This makes your color selection very limited.

We have used FlexSolid for numerous applications, including insole inserts for shoes, smooth and comfortable jewelry, and even functional GT3 belts with tooth counts that cannot be readily purchased off-the-shelf.   The belts pictured to the left are actually being used in our newest proprietary in-house printer, proving its functionality in mechanical parts.

FlexSolid-HoneycombWe also did a stress test by printing out this honeycomb pattern, as we did with Cheetah mentioned below.  I really thought that this print would tear apart, and even seemed to stretch as I was pulling, making me feel that it was about to rip.  To my surprise, after multiple attempts, this material would not tear.  The print even went mostly back to it’s original shape, only slightly stretched.

One issue, as with most unique filaments, is the price.  It is roughly 33% more expensive than PCTPE at a retail price of $39 per pound spool.

Print Settings:

Printing FlexSolid can definitely be a tricky task at first.  Once the settings are perfected the surface quality can be quite good, but trial and error can be frustrating at times.

FlexSolid ComparisonThe photo to the right shows a perfect example of how the smallest amount of setting changes can effect the quality of a FlexSolid print.  The print is a very precise model that can only be done on .4mm nozzles and smaller. From left to right all that was changed was the speed was slowed down from 50mm/s to 45mm/s, temperature brought from 225°C to 220°C, the minimum travel for retraction was bumped up from 1.0mm to 1.5mm, the retraction speed sped up from 15mm/s to 25mm/s, and the distance retracted up from 1.5mm to 2mm.

While it sounds like a lot of edits, each one of those tweaks is so minor that such a small change on a PLA print may not even be noticeable. As you can clearly tell they made a huge difference on FlexSolid.

Support is not ideal with FlexSolid, but it is definitely possible.  We have our overhang support angle to 53° and above, fill amount of 10%, and a distance in the X/Y of .85mm and .18mm in the Z direction.

A full profile for Cura a 0.4mm Nozzle with an e3D setup at .25mm layer heights .ini can be downloaded HERE

Review:

Of all of the flexible filaments we have tried, we have come to use FlexSolid the most.  While Cheetah is a brand new filament that we may start using more often, FlexSolid is our go to for flexibility and a soft feel without an extremely heavy price tag.

NinjaFlex

Strength: 4000 PSI, Elongation: ~500%, Tg: 66C

Ninjaflex Octocat
NinjaFlex

Properties:

NinjaflexNinjaFlex by NinjaTek is a flexible filament that has been on the market for a little while now.  The problem we have always found has been the difficulty to print.  Not only will NinjaFlex print “hairy” if not perfect on your retraction settings, but it must be printed extremely slow.  Priced at $65 retail for a .75kg, along with a print speed of 25mm/s, this material can end up costing a lot of time and money to use.

Ignoring the price and slow print time, NinjaFlex is the softest material we have tested thus far.  There is almost no resistance to folding the bracelet in half, and the octocat pictured above is actually very squishy.  The material is very soft to the touch and would be perfect for anything that is rubbing against your skin.

NinjaFlex is also available in a wide array of colors.

Print Settings:

Ninjaflex ComparisonSince we have not used NinjaFlex for a lot of prints, we are still perfecting our settings.  As you can see from the photo to the left, a minor change in settings can make a fairly large difference in the print quality.  The print on the left was at 235°C, retraction set to a speed of 10mm/s and a distance of 1.5mm.  The print on the right was printed at 220°C with retraction set to a speed of 7mm/s and a distance of .5mm.  The print on the right had a much cleaner surface quality but a lot more cleanup due to the lower retraction settings. We have found this to be the material to get the most “stringy” of the four reviewed when attempting to get a good surface quality.

Along with tricky retraction settings, complex models are just about out of the picture.  Support is very difficult to dial in and extremely hard to remove cleanly.  As mentioned above, we print NinjaFlex at a very slow 25mm/s (compared to 65mm/s for PLA and 45mm/s for PCTPE). These factors can become a big issue when printing large items, complex models, or products for resale.

We printed one model on a PEI bed and soon came to regret it.  While nylon based materials such as PCTPE will not stick properly to a PEI bed, NinjaFlex stuck so well it destroyed our print.  The entire bottom couple of layers delaminated from the rest of the print even with careful use of a scraper with the bed at room temperature.

A full profile for Cura a 0.4mm Nozzle with an e3D setup at .25mm layer heights .ini for NinjaFlex can be downloaded HERE

Review:

While NinjaFlex is a lot of fun to play with, the high price tag, slow print speeds, and difficulty to print complex models has made it so that we have not offered the filament for sale to our clients.  While slightly more soft and flexible than FlexSolid, it is almost always out of the price range and ability to print for client’s models.

Cheetah

OctocatCheetah
Cheetah NinjaTek
Honeycomb Cheetah

Properties:

Cheetah NinjaTekCheetah is a new, yet to be fully released, flexible filament by NinjaTek.  It is named as such due to its ability to be printed much faster than other flexible filaments. The filament was given to us as samples of red filament, but we are not positive if there will be other colors available.

This material printed with an extremely clean surface quality after dialing in the settings on a few trial and error prints. The video to the right is a bracelet printed at .25mm layer heights and it is just about as clean as a .1mm PLA print.  We did have a bit more of an issue getting some sloped prints to be as high quality, but overall the filament prints better than we had expected.

Honeycomb CheetahNot only is does this material look great, it has some amazing properties.  We cannot find much data on the elongation or tensile strength due to how the new the filament is, but we can say it is softer than PCTPE and FlexSolid, and only a little more stiff than NinjaFlex.  The video to the left shows an attempt to rip apart a honeycomb print we designed.  The model was only 4 walls thick (1.6mm) and would go back to its shape after numerous attempts of tearing apart.

We do not know what the pricetag will be on this filament, so it is difficult to compare to the other three materials on feasibility for clients to use.

Print Settings

The number one issue we seemed to find is that this filament has a very low range of temperature for extrusion.  Too cold and the filament will clog and too hot the print will have a very ugly surface quality.  This range was difficult for us to dial in because it seemed that even the difference between two printers could vary our settings a bit.

Quality CheetahNinjaTek’s website states that the range for printing Cheetah is 240° – 250°C.  The print pictured on the left has the material printing too hot at 245°C. The print on the middle was printed at 240°C.  The material oozed at these temperature and gave a look of overextruding.  It actually made me recheck the e-steps on the machine with some PLA, but they were correct.  I even thought about doing a guess and check method with reducing the flow rate, but decided to reprint with the temperature down to 230°C.  The result on the right (along with the bracelet and honeycomb print above) is this material being brought down to 230°C.

I then decided to try a print at 225°C and got filament clogging within the first layer.  This has led us to say that the proper range (at least on our Lulzbot TAZ5 printers with e3D hotends) is 230°-235°C.

Support CheetahCheetah surprised us when it came to support removal.  While we have only tested a very basic model, the support was very easy and had a very clean underside.  We used support with an angle of 53° and above, 10% fill amount, 0.9mm distance in the X/Y direction, and 0.175mm in the Z.

While NinjaTek says the filament can run as fast as 75mm/s, we found the filament to run best at 50mm/s.  This is much higher speeds than their NinjaFlex filament, and the fastest of the four reviewed today.

We also really enjoy the fact that Cheetah required no real heating of the bed and had great adhesion.  We ran our build plate at only 40°C and was able to remove prints from both glass and PEI beds without any issues.

A full profile for Cura a 0.4mm Nozzle with an e3D setup at .25mm layer heights .ini for Cheetah can be downloaded HERE

Review:

The surface quality, along with speed to print, makes this a great material for practical usage.  The main issue comes with the fact that the price is not yet known.  We hope to be able to add this material soon to our list of products available for clients.

Review:

Flexible 3D printing Materials
Flexible Filaments

Each one of these materials has their own pros and cons.  The quality and easiness to print for PCTPE is great, but it is clearly a stiffer product than the other three.  This could end up being perfect for your project, but when soft and flexible is what you need, the other three materials would be your best option.

All four materials can have a good surface quality after dialing in your settings, but NinjaFlex is definitely the most difficult to print.  PCTPE, FlexSolid and Cheetah all seem to to have the ability to print support material without too damaging of results, with Cheetah leaving us with a lot to be excited about.

We have always found that flexible filaments are some of the hardest unique materials to print fast in high quality.  This is why we are very hopeful to offer Cheetah soon to our clients.

Feel free to leave any of your comments below or ask us any questions at info@SD3D.com