Posted by Paul Cronje on December 26, 2015
We received the flexible filament some time ago and had some great fun with it in the meantime. My first impression opening the roll of filament is that it is a lot more flexible than standard plastics, but lets give it a bash!
The most tricky thing with the flexible filament is to extrude it, because the filament tends to buckle after the extruder gear. This is because the filament are being pushed from behind and directly after the extruder gear is where the filament is usually not supported. So we add a short piece of PTFE tubing (about 10mm long) between the extruder gear and the top of the hot end to support the filament. This works like a charm.
The other two changes we made was to reduce the printing speed to below 50mm/s (we used 30mm/s) and to increase the retraction length to 10mm. The reduction in printing speed is also to decrease the possibility of buckling, because the slower the printing speed, the lower the pressure in the hot end. The increase in retraction length is to reduce stringing when the nozzle moves from one point to another (this is when it seems like a spider is making a web on your component). Another interesting thing is that the stringing is less if the hot end temperatures is higher. This means it is easier for the hot end to break the strand of filament at a higher temperature than a lower temperature.
We used hairspray (Fiesta Ultra Hold) on glass as the printing bed at 60 Degrees C. A cold bed should also do as the filament hold very well onto the bed and is very forgiving due to the flexibility. The cooling fan was also 100% on to cool the printed material as soon as possible after printing.
The recommended hot end temperature is 200 - 220 Degrees C. We have printed at 210 Deg C, but had better results at 220 Deg C. The path the filament runs between the spool and the extruder is also very important, because the flexible filament is more sticky than ABS and PLA.
Once your printer is set up to extrude the flexible filament, it prints very easily. Due to the flexibility, it is very forgiving should something go wrong.
We were very impressed with the results. The flexibility is about the same as rubber. It is not as flexible as silicone. The stiffness can also be controlled with the infill amount and thickness of the structures. We would rate the surface finish a 8/10. It is not as smooth as PLA, but it gets very close to that. The layer adhesion is 100% and the accuracy is good.
Something that impressed us a lot was the strength of the material. You will struggle to break it by hand. It is very tough. We printed some key holders as samples. Some of you might have received a sample in your parcel to give you a feel of the flexibility and strength.
Below are some pictures showing the flexibility of the key holder.
Below are pictures of a cell phone cover we printed from flexible filament:
We are currently busy with an upgraded dual extruder design with an auto lift function to print components from ABS with flexible filament between the components to form flexible joints. This can be used to print fully functional fingers for prosthetic hands and feet.
All prices are in USD.