Hey Guys,
I am looking for help troubleshooting an issue with a print. I am printing on my X1C with Bambu PETG-HF that has been dried. The vertical side walls on my print should be straight, but they bow in slightly. Then, when it hits the bridge overhang layer, it goes back to the normal for the rest of the print. Any ideas on what is causing this and what I can do to fix this?
Looks like a warping effect to me.
To help with that, try to print with a warm chamber, low layer height and slower.
Since slowing s(_)€%s, you may however want to consider using the cutting tool to print the part in 2 pieces.
One reason I could imagine:
On the inside of the box, the floor might shield some of the heat from the bed, so that the inside of the walls receives less heat than the outside from the bed. When the inside cools down a little bit more, it shrinks a bit and the contraction lets it bow inside.
You could add some manual support fins that you break away later.
Printing on the cold plate could also help if you have one.
Or you put an additional heat block around the box. But I don’t know how well that would work.
Finally, you could predistort your design, so that the walls are straight after the bowing, but that is really advanced and only makes sense if you want to mass produce them.
I considered adding support fins to break away after the print is complete. I was hoping that someone in here might know the cause and the solution within the slicer settings.
What I find strange about these crooked walls is that each layer is aligned on top of it. Normally, if you have a print lifting from the print bed, it will straighten itself out the more layers that you add. But, with this issue, the crooked walls continue to be crooked until the overhang layer where it gets corrected.
Not really surprising. The warp is obvious when zooming into the bottom of the 2nd pic. On top of the white base, low layer times give little time for the effect to show. At the filament change, there’s an angle change due to the longer cooling time. As soon as the top prints, layer times increase drastically again. You can literally see the cooling effect in the top layers outer angle.
So:
Thank you for the insight. What Layer Height and Printing Speeds would you recommend for a print like this?
I have a new idea and I think, neither warping nor what I explained is the root cause.
You are right that both don’t explain, why the walls are neatly stacked on each other and it also doesn’t explain, why the the walls go outward again in a slope when you reach the top.
I think what happens is, the walls are being printed nicely and upright. But when the first layer of bridges is printed, they cool down and contract and pull the walls together. When the second layer is put on top, it too pulls, so that the walls are bent a bit more and the first top layer (bridges) is also pulled together. After a few layers, the top layers are strong enough to withstand the pulling force. That is when the walls aren’t sloped anymore but straight again.
Reducing speed might help a bit, but I don’t think it can prevent it completely.
Maybe it is sufficient to support the walls at the front only.
Is that PLA or PETG?
Alex, I think you are right. That is the best explanation so far. This was printed with Bambu PETG HF that was dried and calibrated.
you might want to try changing the setting of printing outer wall before inner wall.
If my theory is right then this setting won’t make much difference.
