What is flexible filament?
Flexible filament is a material resulting from a combination of plastic and rubber, they are also known as thermoplastic elastomers. Like TPU and TPE.
This time I did different tests with Polymaker brand TPU95, this is a flexible filament that they recommend printing at a temperature between 210 and 230 degrees and in bed from 20 to 60 degrees.
Flexible filament is somewhat difficult to print as it is not a rigid filament such as PLA, which causes it to bend and become entangled in the extruder’s gear system.
TANGLE FREE PRINTING
Especially in printers that have a Bowden extruder since the route it has to do is longer, risking it to get entangled, on the other hand, in a direct extruder there is not so much problem.
But nothing is impossible and of course flexible filament can be printed on Bowden Printers without modifications.
The parameters that I usually use in CURA to print this type of filament is the following.
Quality: 2 or 1.5
Perimeter: 2 or 3 Wall line Count
50 in bed
Initial layer: 10mm
Fan : on
Initial flow: 115
Wipe Nozzle: on
The quality depends on what you want to achieve, but in general I recommend 0.2 if you are using a 0.4 mm nozzle, the walls on the perimeter I recommend you leave them at 2. In this case I used a 20% fill but you can modify it to your choice.
SPEED IS KEY
The ideal temperature for this brand of filament is 230 degrees in your case. If you use another brand, I recommend you check the parameters recommended by the manufacturer.
In the bed a temperature of 60 although this material has the peculiarity of adhering very well to the bed.
Speed is key in this material and scheme we must print with very slow speeds, for example 25, 30 or even 40 but above that you risk the filament getting tangled.
It is also important that when we are printing without modifications in our printer and especially with the Bowden extruder that we disable retractions, since when pulling the filament when doing the retraction the chances of entanglement are very high.
I recommend instead of this to avoid some strings, enable the wipe Nozzle option or clean the nozzle between layers.
Keep in mind that the printing times with TPU are going to be very long and slow since remember that the speed we are using is very low.
And with these parameters you will surely not have any problem, remember to do speed tests for example start printing at about 20 or 25mm and then you can go up to 30 or 35, to be in a safe range.
At first it is trial and error, it is normal that in some attempt the filament gets tangled. All you have to do is cut off the folded part, remove the filament, and try again.
There is not always luck the first time but once you have your ideal parameters, you will surely have successful prints.