Looking for a bit of help with printing TPU. As you can see in the picture, the lower part of my print is failing, with what looks like under extrusion, or warping or something, but the confusing thing is top 2/3 of the print is fantastic, and the first layer looks great.
I’m using Bambu’s TPU 95A, default Bambu TPU profile and Textured PEI build plate.
Looking for some pointers on where to start. If the whole print was failing then I would look at flow rates, or speed, etc. But as its just the lower 1/3 of the print im stumped. The top part of the print is near perfect.
The part fan is running. So I think that rules it out.
Yes the part failing is an overhang but like you I thought it should print that fine. It’s not an extreme overhang so thought all would be good.
I’m printing an RC plane (eclipson model b), and this is one of the wheels. I’ve been using there suggested layer heights which for this part is 0.13. I’ve changed it to something larger and seeing if that makes a difference. I’m currently printing the part again, just on the first layer, fingers crossed.
These are literally the last two things to print from the 75 or so pieces and not had any issues with the others, but these are the only tpu pieces.
Just to follow up. Looks like layer hight is a massive part of the issue. Changed it to .25 and it’s 99% better. I’ll play around with speeds and feeds to see if I can get the last bit dialed out but thanks for your suggestion.
That is very backwards though, as [assuming the default line width of 0.42] any layer height larger than 0.20 can’t even print 45° overhang. At 0.13 (that’s an odd height btw) you can do 58° overhang (where 90° is a bridge). At 0.25 you can only do 40°. I assume that your better result is actually not caused by the layer height itself, but from the slower speed you trigger because of the overhang.
I would use variable height for that any day of the week. It gives you better detail and overhang capacity than default where needed, and is faster than default otherwise.
It confused me. It is at standard layer width. I think the settings are from an ender 3 as that’s the printer they recommended.
I’ll give the variable layer hight a go and see what that looks like. Kind of interested now in what is going on. I’ll check the difference in speeds aswell to see if there is a difference.
Ok to follow up. Ive printed a couple now with the increased layer hight and they have come out pretty well with the exception of a few failures on the very first layers that are not on the build plate.
Ive had a play around in the slicer and as you suggested the speed has dropped by changing the layer height. Form around 60mms to around 36mms, so yes that is prob having a big effect on it.
Also changing to adaptive seems to basically do the same with the exception of the top most layers as you would expect. I’ll give an adaptive print a go and see what that comes off like.
If I can just get those first few layers not on the build plate to stick i’ll be laughing.
OK. So… Variable layer hight on its own did not resolve it. I have dropped the speed as you suggested for the overhangs 10-25 and 25-50 to 20mms which from what I can see seems to be working, but will wait for the print to finish before I finally decide.
Looking at the variable layer hight print (i stopped it as soon as it started to fail as I was watching which I haven’t been up to now), I can see that for there seems to be barely any overlap on the layer below it. So if this does not work I will try to bump the layer width slightly from .42 to .45 to see if that will helps
I just wanted to share some feedback of the issues i have had with the Bambu TPU 95A filament, I used the stock profile .20mm Layer Height & Unmodified TPU Profile, on my X1C. with the standard volumetric speed of 3.6 i beleive it is, prints are pretty mediocre with Zits, Blobs and underextruded areas, i searched and searched and changed settings with no improvements.
In the end i changed max volumetric speed inside the TPU Filament Settings to 1.00 from 3.6
This entirely solved the issue that the print looks very poor quality, the part now looks amazing. I would ideally in one way or another get the print time back to an acceptable time but for now if your looking for a quick resoltion then drop that max volumetric speed! Hopefully the new High Speed TPU that they have listed on the website fixes that issue and allows a print speed of atleast 3.6 MVS again. will be a test for another day.
I also had the same issue as the OP, with filaflex 82A. I tried wall thicknesses, layer heights etc, but after reading this thread, I lowered the flowrate from 3.6 to 2.0 and the problem was gone.
