I’m new to 3D printing and have been tasked with doing printing some test objects with a very soft filament and only around 5% of my ~2cm sized test prints have been successful at all. Mostly they are very stringy (under extruded?). The bed adhesion is perfect and the layer adhesion is good. It just seems that it is not extruding enough or consistently - even within one print.
Details:
Printer: X1C, latest firmware - feeding the filament directly into the print head from above to reduce bowden tube friction.
Slicer settings are pretty standard standard “0.2mm Standard @BBL X1C”
The filament I’m using is a new, soft, flexible TPU type, approximately shore 70A. It measures around 1.55mm diameter and is quite stretchy and slightly tacky.
Edit: Dried for over 30 hours in a 70C lab oven.
I’ve tried over 40 combos of feed gear tension, temperature, fans, diameter, flow ratio, retraction, volumetric sped, etc. and have only achieved 1 or 2 “clean-ish” test prints. Most fail as spagetti somewhere along the line. But sometimes layers alternate between some fairly good ones and some under extruded(?) ones.
What am I missing? What other things should I try? How can I methodically get to the bottom of these problems and achieve successful, clean prints?
(I also have some Recreus Filaflex 70A TPU that I have also tested with and have been somewhat more successful printing tests with it. But not as clean as PLA, but I guess that is to be expected.)
Thanks for any insights or tips for this n00b jumping in the deep end!
You definitely shouldn’t store TPU in a room with 41% humidity. It’s not like PLA where you can leave it out. How long after drying did you print those models?
TPU, Nylon and such are not filaments for the beginner…
One should start with something simple, like PLA so the vital things can be learned and used to
But let’s see…
TPU needs drying and for that stuff it still is best to print right from the dryer as it collects moisture right away.
A bit like how some gain weight just by looking at sweet things, TPU WILL absorb moisture better than desiccant.
Trusting what’s written on the roll or in the profile is great, CONFIRMING the filament IS calibrate is better.
A few simple test prints won’t waste too much compared to a bunch of larger models that keep failing…
I feeling like I’m running out of parameters to test. I haven’t messed with layer height yet, but pretty much everything else. It seems like it’s really touchy.
Also I’m just wondering, where did you get that build plate? That build plate has been discontinued for a while and I would like to get one. Or did it come with the printer?
Assuming you have some PLA give that a go.
Check the settings and if required adjust so you get a test print looking as good as possible.
Use the same layer height as what you want to use for the PLA and set this print aside for reference.
Dry your TPU before trying again.
Then print a simple cube or such and observe the print.
If it comes out fine go ahead, any signs of struggle and you calibrate the TPU.
What you use is very soft and not easy to print to begin with…
No offence but that looks about as bad as it can for a printed part…
Ok, let me try to wind down your settings a bit…
Disable the scarf seam, disable the arc fitting - the later is not really important here though and only helps with geometry for some objects.
Use a much easier sparse infill pattern, like honeycomb where the filament has it easy to work and stick.
Set the CORRECT filament diameter, if you use 1.75mm don’t set it 1.5mm as all hell will break loose with the print quality.
Like this I can assure you that your extrusion isn’t even close to being calibrated, so fix this part first and do a proper calibration with 1.75mm set for the filament diameter.
While abusing the max volumetric speed to reduce all extrusion related things it does not really affect non-print moves.
So while racing like a snake during an extrusion move the head crawls at lightspeed to the next line to extrude again - creating a terrible mess in return.
Try it the other way around for TPU>
Select a high quality profile as they comes with much slower speeds and lower acceleration values.
Adjust the layer hight back to 0.2mm and save it as your TPU base print profile to adjust and fine tune.
Once done try a simple test print with it and before the first layer starts press the silent button.
Now the printer really prints dead slow…
See how well it does with like a test cube and if the first 20 or so layers are fine set the print speed to normal and keep observing.
If normal still prints fine you know the speed is ok, if slow is good while normal looks worse you know those print speeds have to be cranked back a bit.
They look “gooey” but at least they are not under-extruded. It seems like I get one or the other. Below is one with a 1.85 flow ratio (vs. 2 for the above ones) and somewhat higher speeds. Way under-extruded.
If you now would calibrate the filament rather than just guessing we might get somewhere
I doubt it is just 1.6mm in diameter and I also doubt that a flow ratio of 2 the result of a filament calibration.
Trust or don’t but without a proper filament calibration you won’t get anywhere and keep wasting expensive filament.
Nozzle temp, flow ratio, k-factor, after that the calibration patches should come out nice and clean, same for a Bambu Test Cube.
1.6 may be a little on the low side. I went in and double checked about 8 places in a few meters of filament and got readings of 1.6 - 1.64. I’ll update the profile to 1.62.
That’s getting odd…
The second line from the bottom seems to the cleanest in the pic and I would try a k-factor in that range for the first round - BUT that won’t make any difference with this terrible finish.
The temp should be somewhere between 220 and 250ºC and needs to be honed in manually for best results, I would start on the lower end to avoid bubbling.
Filament wise I don’t even know if the slicer can handle such big losses.
Seems quite impossible to do a calibration.
Those patches look as if your hotend is suffering from a partial block or that your extruder fails to transport the filament.
