Printing with TPU
Hi there,
I have experience using TPU/Ninjaflex with Printrbot Printers, so I tried using similar settings to print on my Prusa i3 MK3S. This was a huge mistake as, despite the slow print speed (20), the Ninjaflex filament got all tied up inside the gears that turn down the filament, resulting in it not printing and I had to take apart and reassemble the extruder casing to cut it out.
I'm using Ultimaker Cura and didn't use the default TPU settings, instead opting for making my own settings profile for Ninjaflex filament based on notes from my previous experience with the material on other printers (also the default TPU settings didn't seem right to me). I'm guessing there are a few considerations I should keep for the Prusa model. Any tips on how to print in TPU/Ninjaflex with the i3 MK3S?
RE: Printing with TPU
slow printing speed, low extruder gear tension, look at the provided flex filament setting for a starting point
RE: Printing with TPU
slow printing speed, low extruder gear tension, look at the provided flex filament setting for a starting point
Tips for settings? For my notes, I mainly use Temp: 220 C, All Speed: 20. Also, gear tension?
RE: Printing with TPU
Any instructions for setting the best tension?
i3 Mk3 [aug 2018] upgrade>>> i3MK3/S+[Dec 2023]
RE: Printing with TPU
One suggestion I read quite some time ago, and from friends printing TPU, loosen the tension screw(s) until there is no spring contact (no tension), then turn the tension screws in 1/2 turn. In other words, start with as little tension as possible.
RE: Printing with TPU
One suggestion I read quite some time ago, and from friends printing TPU, loosen the tension screw(s) until there is no spring contact (no tension), then turn the tension screws in 1/2 turn. In other words, start with as little tension as possible.
Question, is this tension setting done with the filament installed, or with the filament path clear?
FWIW, I haven't had much problem with my tension set about 1/2 turn looser than regular filament. I have my max speed throttled by setting a max volumetric flow of 3.61 mm^3/s for my NinjaFlex 85A (empirically found by feeding 60mm at different rates, this was about as high as I could go to keep from getting kinks right in the top of the PTFE tube under the bondtech gears with an extruder temperature of 230°C. (Lower extruder temperatures will require slower feed rate.) I'm still trying to minimize stringing though...
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RE: Printing with TPU
My approach is to unscrew it during print until it slips through and then slightly (like half turn) put a pressure on it, so it doesn't slip anymore.
My Temp for Ninjaflex is 230-240C. I also set all speeds to 15mm/s. Fast speed changes is what sometimes generates back pressure.
Don't underestimate first layer. If it's squished, you might get issues in the following layers pretty fast.
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RE: Printing with TPU
This may not help you immediately, but I built a skelestruder and use capricorn tubing and just throw whatever filament in without having to adjust any tensions or mechanical settings and don't have any problems or slipping.
All I do is adjust print speeds and temperatures. I did follow advice to turn off retractions with TPU, boy was that a mistake, retractions back on at 0.5mm, and yes I do get some stringing, but stringing is better than blobs!.
So maybe the issue is with the extruder design not being optimal for TPU.
Skelestruder has a shorter filament path to the nozzle tip plus using capricorn tubing which has a smaller inside diameter than the PRUSA supplied tubing. All this helps keep squidgy filament under control as it has less room to squish about.
This is a video by JLTX who designed the skelestruder and is printing Ninjaflex.
Note this is an early prototype of the skelestruder, which has now had improvements.
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RE: Printing with TPU
One suggestion I read quite some time ago, and from friends printing TPU, loosen the tension screw(s) until there is no spring contact (no tension), then turn the tension screws in 1/2 turn. In other words, start with as little tension as possible.
Question, is this tension setting done with the filament installed, or with the filament path clear?
Buddy says with filament in - so ultra light tension. With the MK3S offset, one might wonder is no tension will work (I've heard a few say they can print PLA with the idler door open).