Prusa Mini: First Prints with Ninjaflex

Since getting my new Prusa Mini I’ve been using it mostly for printing with ninjaflex, believe it or not. My homemade lulzbot mini was able to print nylon but i was never able to use ninjaflex (without buying or making another printhead capable of doing so). I do plan to do that at some point, but the new Prusa Mini was advertised as being FLEX capable. And that is one of the main reasons i chose it. That and the flex build plate. And because Prusa is a trusted brand, and it was cheap, and Lulzbot let me down and went down in flaming ball of smoke more or less. Thanks Jeff Moe.

Some have said that a bowden-style printer, which is what the Prusa Mini has, are generally not friendly when it comes to printing flexible rubber filaments. I can now see why, as they are harder to feed through the long tube without the filament having issues. Despite this i have been printing very well with flexible filament, and using clear Ninjaflex specifically.

The Prusa Mini does not have a dedicated filament profile for ninjaflex, presumably because ninjaflex is on the very stretchy side of the TPU filament line and is the one most likely to cause issues. Despite this i have figured out how to use it without major issues. The only issues i had were when i was first feeding the filament into the extruder and setting the layer height on the first layer. In the prusa slicer i just picked the most detailed setting and the slowest setting possible under the generic FLEX filament settings. These seem to work okay actually.

In order to feed the Ninjaflex into the extruder i had to first take off my filament sensor module. With the filament sensor removed i fed the nijaflex through it first and then proceeded to insert it directly into the bowden motor. Once the motor had grabbed onto the ninjaflex i was then able to press the filament sensor back on and finish calibrating the first layer. I did run into an issue when i was trying to purge the PLA. At one point the ninjaflex got pushed too far past the feed screw and got stuck. I had to back it off and try again once i noticed it stopped feeding properly. Other than that the only other issue was calibrating the layer height properly so it would stick to the bed. Early on i had it set too far away from the bed to stick fully.

The first layer calibration for a smooth PEI plate for PLA was -0.650, and -0.875 for Ninjaflex on a textured bed plate. I heard the textured bed plate was designed specifically for flexible filaments and eliminating glue sticks so i got myself one. It seems to work really well, so i have no complaints. Way easier than the glass bed with PEI on my Lulzbot Mini. The fact that i have a smooth bed and a textured bed is not a bad thing since i will be upgrading / modding my Lulzbot Mini soon to have the exact same build plate the Prusa Mini is using. In fact, some of these Ninjaflex parts are for that exact Lulzbot Mini modification.

The reason I’m using clear ninjaflex material is because i am also modifying a bumble ball toy for my new 5 month year old daughter. I am planning on recreating something similar to the toy found in Star Trek Voyager: Friendship One. The one that lights up and plays a child rendition of Vivaldi’s Spring. After printing one test bumper and then tweaking my model i think the new print has come out very well. My prints for the prusa mini bed plate adapter for the lulzbot mini have also come out well, i am just waiting on some threaded standoffs so i can proceed with that mod / project. More updates on that to follow soon.

All in all I’m happy with my new Prusa Mini. The bed size is great, i have no stupid leveling washers to worry about, the bed is flexible to remove prints easily, and the machine is very capable for a decent range of filaments. Nylon would be nice, but with the almost inability to print with ninjaflex i probably wont push my luck.

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