6mo ago

What could cause this botched surface?

What could cause the strange part on the right? The whole surface should be the same, it's a 90° wall, so nothing that should look like this. Can't see anything strange in OrcaSlicer. BambuLab A1 Mini with Creality PLA+

15 comments

Spontaneous ideas for troubleshooting:
Disable the stepper motors, slide the head to the position it would be in when printing this section, and check for any irregularities in the rail or belt.
Clean the hotend.
Try to print the part again, see if there is damage at the same section.
- Started the print again because i need this part multiple times anyway. It starts to "fail" at the same corner again.
  Edit: Not exactly the same damage, but at the same height. Looking at the last print, it's not just that corner, it's all around at the same height.
  
  If it’s a band one thing you can check is if the build plate is sufficiently torqued down. I spent ages chasing down a weird z issue, to the point where I converted my ender 3 z axis to being belt driven, and would still get really weird bands at certain heights. Turns out the bed was ever so slightly loose and at certain z heights would go into a tiny resonance frequency causing bands in the z axis. I’m not too familiar with the a1, but it’s a possibility that no matter what I researched I never saw mentioned
  
  Is it that height and up or just a band?
  
  If prints are failing at a certain height, you might have a z axis issue. You can try cleaning, lubricating, and calibrating the z.
  
  Same height? Check if the vertical axis has a bump/rough spot right there. I've found that single vertical point issues tend to mean I need to lubricate the rod again.
It looks to me like your printer is printing on slightly melted plastic. I don't use orca or a Bambu, so I don't know if you're able to do this, but I would try printing that section slower, or changing the minimum layer time. It looks like that's a small cross section so it's probably finishing the layer and starting the next before the previous one has cooled down.
I can only guess the print orientation but it looks like curling to me. Basically on that side, the part cooling fan (or lack thereof) is making the plastic of overhangs curl more than on the opposite side which gives you this bad surface finish. Otherwise maybe a retraction issue but that would probably show in other places too (oozing).
Check the position of the seam in your slicer. It shouldn't be on overhangs - I think this is what's happening here.
- Seam is at another position, far away from that part.
Check the whole path of the filament, or maybe rotate the part before printing. Sometimes a combination of factors can cause just enough friction to under-extrude in just parts of a print. I sometimes get it when the filament roll rubs on the holder. This looks like it could be that it's doing a fast bit while twisting the Bowden tube.

15 comments