Submitted 7 months ago by the_third@feddit.de to 3dprinting@lemmy.world
https://feddit.de/pictrs/image/8b8f78d5-4ff8-4e11-854e-a302c9609b9f.webp
Here’s the whole printer during that print…
…and here’s a detail image:
The printer is a Creality CR5 Pro HT running Klipper - although I doubt this is too relevant. The extruder is of the “push type” with the hotend only including the heated nozzle. Current speed is 70mm/s in the layers but at the moment of the video 35mm/s due to the top layer.
I have no idea why, with a relatively symmetrical print just this corner is so messed up and underextruded. Any idea would be nice.
Two guesses:
Someone else pointed out that your Bowden tube looks a little pinched in some of the corners, I can’t tell which corner is underextruding from the video but possibly there’s filament slippage from that?
Is there any oozing from the nozzle? If the corner with the problem is the “start” corner, any plastic that oozes out during travel isn’t making it into the print. Depending on your slicer you should be able to randomize the start location per layer to try to hide it, but if that’s the cause I’d try to figure out why it’s oozing so much.
Someone else pointed out that your Bowden tube looks a little pinched in some of the corners, I can’t tell which corner is underextruding from the video but possibly there’s filament slippage from that?
Yep, it is exactly that corner where the radius of the tube reaches its minimum. I think that is a hot candidate for the main issue. Also after removing the print, it turned out the the outside had this issue as well and that was printed in the other direction. So, coming out of the slow corner the flow couldn’t accelerate quick enough to get back to volume due to high friction. Thanks, see my edit, I’ll report back!
Yeah, if there’s not much travel distance between layers I’d say the Bowden tube is gonna be your culprit. Looks like if you just remove the tie connecting the tube to the cables going to the print head you’ll probably be fine, definitely report back!
Check your bed bearings. I had this happen when one of my bearings started to let go. I also found a deformation in the bearing channel, so I switched that unit to MGN12 rails and the issue went away.
Bed leveling could be the problem, under extruding due to a low spot on that corner.
Bedmesh was created right before the print and applies, I’d rate that second after underextrusion due to the bowden tube getting bent hard. We’ll see though!
Looks like lots of underextrusion, but I don’t know why.
Yes, definitely underextrusion. See edit for idea, test following tomorrow.
empireOfLove@lemmy.one 7 months ago
What kind of plastic?
When it reaches that far back corner it looks like your Bowden tube is getting close to being pinched. It’s probably too sharp of an angle leading to too much resistance for your filament and drive motor, that’s what causes the underextrusion. Bit of a design flaw tbh.
Double check your drive teeth tension it might be slipping excessively when the Bowden tube gets to that extreme angle and push resistance gets too high. Also consider trying to reposition the tube so it doesn’t experience such angles.
the_third@feddit.de 7 months ago
Yes! That might actually be the case. We come out of the corner with a low flow rate, because, corner and low speed and the flow can’t increase quickly because of friction. Hm. I’ll reroute that Bowden tube and test again tomorrow.
empireOfLove@lemmy.one 7 months ago
Yup, seems the most likely problem. Bowden tubes are a pain… good luck!