Hey Folks,
Ive had this issues on quite a few prints lately when printing with ABS. Does anyone know how to fix this issue? Could it be because of the overhang and therefore the filament cannot be placed correctly on the edge and get “slided” around the corner by the nozzle? (no adhesion on the corner point)
My guess is that the overhang is curling up slightly and causing that irregularity as the nozzle goes by. Try printing on silent mode to slow the speed %50 and see if that cures it. If it does, play around with the outer wall speed.
thanks mate, thats also what i suspected.
What i didnt mention: in the bambu studio screenshot, i displayed the layer speed which is super low at that “purple” line.
Could it help to print the inner first on those areas? therefore the outer lines on the problematic layer have nowhere to escape / be misplaced?
That might help but you’re still printing that layer over air and it will tend to curl or droop.
The best thing to do is modify the holes design slightly so it doesn’t cause an issue.
Holes Horizontal
Recommended Value: a ≈ 0.3 mm
In order to print horizontal holes with a better tolerance, it is recommended to model the additional features in the image where the offset distance a, is the layer height of your print. If you are using a small layer height like 100μm you should do 2*a. This will accommodate for any drooping that will occur in the steep overhang sections of printed horizontal holes and the “flattening” of the bottom of holes due to the stacked layer process.
That corner you circled, you’re printing over air. There’s nothing for the filament to stick to so it gets dragged a bit. You can fix this with supports (but they can be hard to pull out of the hole afterwards) or possibly by reorienting your model. Otherwise you have to live with it. It’s the nature of FDM printing and not a defect with the printer.
Why is the corner on the bottom of the hole needed?
Thanks for that link, some useful suggestions there. I added it to my 3D printing bookmarks.
While the issue isn’t as bad as the overhang section of of a horizontal hole it does show up in the lower area as well. If the very bottom of the hole doesn’t land exactly between the layers then the slicer has to print another layer which “flattens” the bottom of the hole. Image below to illustrate.
This is why smaller horizontal holes often look “oval”. The bigger the hole the less of a problem the bottom is and the more of a problem the top overhang is.
Thanks. I erased my question because I saw that it was explained in the link you included.
I saw that but I still posted as others reading in the future might have the same question.
I don’t really understand what they are suggesting to do in the link you gave regarding the Unsupported Holes on the bottom of a part (section under Unsupported Edges). Are you able to explain it a little better?
The trick here is to “build” a surface in CAD that the printer can bridge correctly on either side (or in several orientations depending on the hole size) that the hole wall can then be printed up from.
A good video describing the issue and different solutions.
I’m trying to understand the picture you showed. Did you do three extrusions instead of two like the instructions? Each of a rectangle with depth of 1 layer at a different rotation? Also is there a little gap between each rectangle layer where they don’t overlap?
Yes, the concept is explained really well in the video at 6:36 and onward.
Yes, I am looking at the video now. I originally thought the picture was something you did, not from the video
