RE: Printing TPU on the MK4
Ninjaflex is fine but it needs the hot temp, 246-248. I printed a ninjaflex keychain on the first day after I upgraded my first MK3S -> MK4.
I was actually surprised it worked first time.
I have attached the zipped .3mf. This includes 3 color changes. I've printed 3 of these so far. No issues. This much more reliable than when I was doing it on the MK3S+
RE: Printing TPU on the MK4
After reading some of the previous posts, I decided to start with the basics. I live in a dry climate (Montana) and usually try to finish a spool of filament quickly after opening. I had assumed that the filament would remain dry enough until finished. I dried the partially used spool and started another print. It worked perfectly. I tried and double print and it also worked perfectly. I learned that you can't assume the filament is totally dry upon opening and inevitably will absorb even more moisture after opening. Problem solved.
RE: Printing TPU on the MK4
yeah, TPU in particular needs drying. I live in CO, which is pretty damn dry too lol, but I still dry my filament and put in a ziplock back with desiccant pack when in not in use. I dry after each use depending on the length of the print.
RE: Printing TPU on the MK4
The TPU that you print seems to be quite hard. Has anyone ever tried to print the Recreus 60A filament?
RE: Printing TPU on the MK4
Nope, ninjaflex is the softest I've tried. Even NinjaTek's chinchilla doesn't go that low. https://ninjatek.com/shop/chinchilla/
60A sounds like an exercise in pain and frustration lol I've still not gotten my ninjaflex dialed in since upgrading to MK4. I get a bit of under extrusion with the stock profile. I need to do some tests and possibly up the extrusion multiplier slightly. I'm gun-shy about getting too aggressive with it because of my early days with trying to print tpu on the MK3S and having it wrap around the extruder gear....
The TPU that you print seems to be quite hard. Has anyone ever tried to print the Recreus 60A filament?
RE: Printing TPU on the MK4
Back when the Mk3 was getting Linear Advance (LA) I started modifying PLA profiles for Ninjaflex (then Semiflex, now Cheetah). I just used this approach on the Mk4 and have been printing Cheetah with no problems.
The reason for using modified PLA profiles is I don't want any "magical TPU settings" messing with things, I want fewer variables so I can intuitively troubleshoot. I noticed the print times with TPU profiles on the Mk3 were hours longer than with a PLA profile using the same settings. This is probably the LA K-factor, but the way this was implemented on the Mk3 gives me a headache to contemplate. The MK4 with Input Shaping (IS) is probably more confusing. I haven't done this with IS profiles and I don't think it's a good idea to use IS/LA magic with TPU (although it is beautiful to contemplate in theory, trying to outsmart TPU is a fools errand).
I do the same thing every time: I take a 0.20 mm-layer-height PLA profile that I like and set all the speeds to 30, the accel to 250, and then I set all of the widths to 0.6 (default/perimeters/infill) and 0.5 (external/top solid). Solid to 0.55 (an intermediate value), and first layer width to 0 (so the 0.6/0.55/0.5 settings apply to the first layer). Back in the day (when we were all just trying to get our printers to work), extrusion width was 1.25x to 1.5x the nozzle diameter. Prusa backed away from this over time to compete with the crisp look of prints coming off the Chinese printers, and since in this case that is the least of our concerns, I see no reason to nats-ass ninjaflex prints. You want to get this extrusion system going and keep it going, so 0.43 external perimeters are out. That's dumb, don't do it.
For temps I set a PLA profile to 240 and 50. You can change the flow rate to 4 or 5 when you are in there, but to be honest, you can crank some flow rates with Cheetah, especially on infill when there will be less backpressure. Sometimes I use 3d honeycomb so the "3d squish" is more even, and in that case the infill gets an accel of 150, but if you are doing rectilinear you could probably get away with very high flow rates using a 0.7mm wide bead at 30 - 40 mm/s with an accel of 500. The filament seems happiest at steady-state, even if that steady-state is a high flow rate. This is why accel and retractions are so important. I do leave the travel accel cranked (200 mm/s at 1250 mm^2/s), and am unsure if this accel affects extruder motor accelerations (I've never checked, but I suspect it does).
Also remember you've got the box for "only retract when crossing perimeters" in the infill tab, which I actually don't use (because you may get holes in your perimeters), but that could help support the higher infill flow rates.
For the extruder, I set retractions to 3 mm at 30 / 10 mm/s with 0.1 or 0.2 extra on restart. Wipe on; retract 70% before wipe.
I even accidentally printed a part at 0.125 mm layer height the other day (I changed everything as described here but used a 0.125 mm profile and forgot to change the layer height). Didn't look good, but it wasn't underextruding or jamming. I think the poor appearance was probably from the "skim coat" balling up.
For the really flexy stuff, I try to avoid it. But, when it is necessary, I just lower the accels and speeds more. Also, best not to leave it unattended. I trust Cheetah at this point.
Lastly, the guy that dried his TPU should try throwing some salt over his left shoulder before every print. I have to dust mine off sometimes because it's been sitting out for months. Doesn't matter. Literally every other filament I use goes in a dry box, simply not required with TPU (Ninjatek obviously feels the same way because they don't even put it in a bag inside the box). Same thing goes for the guy that linked retraction speed to print speed in his mind. These connections (filament moisture and print speed/retraction speed) are false and borne out of desperation. I'm guilty of that as well (I switched to using PLA profiles out of desperation), but that connection has proven useful for years. When printing, the extruder motor is moving very very slowly (1 - 5 mm/s?). 10 mm/s detraction speed is actually still an aggressive setting if you think about it. But, if you link retraction speed to print speed, you won't think about it.
Quinn
RE: Printing TPU on the MK4
I’m somewhat surprised people have been having so many issues with TPU. I’m using ninja flex and just loaded the stock IS profile and everything I’ve thrown at it printed fine(so far, a series of coaster “feet”, most printed 4 at a time, a rectangular bottom for a doorstop and the seal for https://www.printables.com/model/575930-drybox ). I’ve loaded it multiple times and, aside from having to push in a bit more to get the filament detector to register it, have had no issues. I was thinking of ordering some Filaflex 60A just because this thing seems to be able to handle any filament I care to print. Maybe I’m pushing my luck a bit, though, and should just go with Varioshore…
RE: Printing TPU on the MK4
I am new to 3D Printing and just finished building Prusa Mk4. having issues with TPu not feeding into extruder. Using tpu 95 from Polymaker. after much trial and error playing with adjustment screws and no luck. i found by turning off fillant sensor tpu was able to load and object printed.
RE: Printing TPU on the MK4
So I just went through this exercise on both the XL and on MK4 for ninjaflex and for chinchilla.
This works reliably for me
https://forum.prusa3d.com/forum/original-prusa-xl-tool-changer-how-do-i-print-this-printing-help/tpu-ninjatek-ninjaflex-specifically-on-the-xl/paged/2/#post-696515
I've not had a chance to go back and try increasing mvs to closer to the stock profile's value of 3, but the jamming seems to be primarily a function of the retraction. I've had good success with the settings mentioned on both the XL and my MK4 printers.
RE: Printing TPU on the MK4
I think it just behaves so differently than rigid filaments. 92+ is generally not the same as something like 85 and below. you definitely have to respect the filament lol. With tpu(and really most types of filament) I want reliability over speed. It's why I don't use IS at all. If I print a design a lot I'll spend some time trying to tune things, but generally I'm a slow and steady vs fast kind of person.
I’m somewhat surprised people have been having so many issues with TPU. I’m using ninja flex and just loaded the stock IS profile and everything I’ve thrown at it printed fine(so far, a series of coaster “feet”, most printed 4 at a time, a rectangular bottom for a doorstop and the seal for https://www.printables.com/model/575930-drybox ). I’ve loaded it multiple times and, aside from having to push in a bit more to get the filament detector to register it, have had no issues. I was thinking of ordering some Filaflex 60A just because this thing seems to be able to handle any filament I care to print. Maybe I’m pushing my luck a bit, though, and should just go with Varioshore…
RE: Printing TPU on the MK4
I'm new to printing with TPU, but I have had a couple of ok (smaller) prints. My last print failed late last night at 12 hours into a print of about 14 hours, which is quite disappointing. The Sainsmart TPU had a small jam near the bottom of the gear assembly and after that, failed to feed. I happened to notice it after a couple minutes, where it was printing air at a 1mm from the last surface. Nothing was extruding. Sadly had to kill the job.
From reading above, I see there are some recommendations of possibly lowering MVS. I can try just lowering the value from 5 to 4. However, it isn't clear if the tension needs to be adjusted for TPU. I set it according to the initial kit assembly instructions, and haven't touched it since. What is recommended tension for the MK4 with TPU? I found recommendations for the XL were to tighten rather than loosen, but I'm not sure if this is applicable to an MK4.
Even with the Prusa supplied Sainsmart TPU profile I am getting fine stringing, but first the jamming problem needs to be addressed. I'm really quite new to this and find it confusing to read and sort through conflicting information. Thanks for any and all insight into this issue.
RE: Printing TPU on the MK4
take the temp down to like 218. The sainsmart really isn't meant to print at 230. It never hurts to lower the MVS. yes, the XL needs to be tight. The general rule on the MK3 was to be super loose. I've not found this to be the case on the MK4. The stringing you are seeing is due to temp. The lower temp should eliminate the stringing for sainsmart.
RE: Printing TPU on the MK4
take the temp down to like 218. The sainsmart really isn't meant to print at 230. It never hurts to lower the MVS. yes, the XL needs to be tight. The general rule on the MK3 was to be super loose. I've not found this to be the case on the MK4. The stringing you are seeing is due to temp. The lower temp should eliminate the stringing for sainsmart.
Thanks! I'll try the lower temp, and increasing tension a half turn. Already downloaded the idler-lever linked in similar threads. Hope I won't need to print it, but will if I get jams again. I'd rather not repeat printing only 110mm out of a 180mm TPU part again.
RE: Printing TPU on the MK4
do some small wide test prints first. I've not swapped out any parts at this point. My two MK4s just had all the parts printed in a different color(lime green) and material(ABS). But they are the stock parts. The MVS will help with how much it tries to feed through at a time. It's pretty much the master control valve regardless of what's being printed(e.g. perimeters, infill, etc). For ninjaflex I leave the temp at 238 but I lower the MVS way down. It's slight tweaking between the XL and MK4 but nothing radical. I even got chinchilla to work lol SLOW is your friend for this stuff. The softer the slower you need to go
RE: Printing TPU on the MK4
do some small wide test prints first. I've not swapped out any parts at this point. My two MK4s just had all the parts printed in a different color(lime green) and material(ABS). But they are the stock parts. The MVS will help with how much it tries to feed through at a time. It's pretty much the master control valve regardless of what's being printed(e.g. perimeters, infill, etc). For ninjaflex I leave the temp at 238 but I lower the MVS way down. It's slight tweaking between the XL and MK4 but nothing radical. I even got chinchilla to work lol SLOW is your friend for this stuff. The softer the slower you need to go
By small wide, what do you suggest? A 50x50 square about 0.6mm high, or?
RE: Printing TPU on the MK4
Something tall enough to give you bottom layers, infill and some top layers. Ideally with the same settings you intend to use with the final model. that should give you a good indication if things are going to jam, etc. 50mm is fine you could even do 20 or 30. I was using a 20mm xyz calibration cube for my tests
do some small wide test prints first. I've not swapped out any parts at this point. My two MK4s just had all the parts printed in a different color(lime green) and material(ABS). But they are the stock parts. The MVS will help with how much it tries to feed through at a time. It's pretty much the master control valve regardless of what's being printed(e.g. perimeters, infill, etc). For ninjaflex I leave the temp at 238 but I lower the MVS way down. It's slight tweaking between the XL and MK4 but nothing radical. I even got chinchilla to work lol SLOW is your friend for this stuff. The softer the slower you need to go
By small wide, what do you suggest? A 50x50 square about 0.6mm high, or?
RE: Printing TPU on the MK4
Hmm, in my case the part is with 100% infill, but hollow parts and internal bridging, I have internal ribs to maintain the part strength. I'll come up with something, but will make it smaller, so I can get more immediate feedback.
RE: Printing TPU on the MK4
yeah every model is different and sometimes has different settings accordingly. If you're willing to share I can try a test print for you. I have both the XL 5T and two mk4s so can tell you if the xl requires different settings.
RE: Printing TPU on the MK4
I will make something up and post it here. Thank you.
RE: Printing TPU on the MK4
I have created a quick stl file, haven't even imported it to PrusaSlicer. Do you want me to attach my (new) 3mf file or just the stl?
yeah every model is different and sometimes has different settings accordingly. If you're willing to share I can try a test print for you. I have both the XL 5T and two mk4s so can tell you if the xl requires different settings.