I’m fairly new to 3d printing, and have played around with an Ender3, and have now purchased an X1C.
I have an issue with printing a round cylinder with bottom… I’m not sure what this is called, but the cylinder bottom seems to be “smaller” than the cylinder, although it is the same size on the model. I have tried various different settings, but can’t seem to find what is responsible for this…
I initially thought the issue was because I made use of Fusion’s “Save as Mesh” function… I then tried to “Save as Mesh” with higher mesh detail which made it slightly better. I then started using STEP files, which made it slightly better again, but the problem did not completely disappear, and I’m not sure what causes this…
I would say either your threaded rods have to be cleaned which I didn‘t think can cause this much of a problem until I saw it myself or tighten your belts…
Just an advice no guarantee but wouldn’t make it worse.
It looks to me that the bottom layers shrink at a different rate than the wall layers causing a slight difference in diameter.
I don’t have a fix for this, but what you might want to try is to put a fillet on the inside of the cup so the transition from the bottom to the wall is more gradual.
If you can’t do that you might want to play around with cooling settings.
I’m going to guess that the floor of the cylinder is at the height of that step. I’ve seen that before. It is not a Bambu issue. It’s an FDM issue. I don’t really know the root cause, but I’m guessing it’s shrinkage of the plastic over the large area of the solid infill.
I’d try dropping the temperature some. The default 220C is fairly high for PLA. Might try printing on a heated bed to reduce the temperature differential. For a part that size, I’ve had good luck with the smooth high-temp plate. The textured PEI bed is my favorite.
I’ve not had that problem (yet), but I would experiment first by changing the Quality>Wall Generator type between Classic and Arachne. Next option would be changes in Quality>Advanced>Order of walls.
Today I run into the same problem as I tried to print a vase. And I think, @Chris1974 is right: It’s because of the filament shrinkage. The bottom of the model are solid layers and the higher layers are only a small number of thin walls. So the huge amount of filament on the bottom shrinks more and faster than the walls above. I did several attempts to reduce the problem:
This was the initial print of the lower part of the vase. You can see the solid bottom shrinks much more. A measurement showed me a shrinkage of 1mm for the 100mm diameter of the bottom. That’s 1 percent. The material shrinkage is given with 0.3%.
The first attempt to prevent the visibility of the shrinkage was to smooth out the transistion from bottom to the walls using a fillet. The result was slightly better but not good enough.
This attempt were a modification of 2: instead of a fillet I used a chamfer to reduce the visibility… without success. Interesting is, that the small upper edge of the shrinkage area is the upper layer of the chamfer or the fillet and where the walls only layer starts.
This is the same as before, butt the bottom is only half of height as before. This changed the visibility much more than all variants before.
Now I removed the chamfer again and stay with the thin bottom and got the best result until now. Only a very thin line was visible now. This is one layer, which shows some inconsistencies in comparisation with the other layers.
But all this was not enough, I thought. Shrinkage depends on temperature and so I played with the temperatures. In attempt 6 I set the part cooling fan to 0 for all the solid bottom layers (7 for this slice) and added a brim.
And with the result, I think I can be happy. Yes, with the “wrong” light and if you go close enough, you might see the little variations in the layer, but hey… in comparison with the beginning it looks nearly perfect (for me).
Can happen with overcooling via the AUX fan. All filaments shrink and warp, ABS more then PLA, but PLA too. When I do large prints that prints close to the AUX FAN outlet, I turn it off completely. Sometimes I will flip it back to 40-60% after the first 10± layers. Sometimes its not necessary at all with large prints as the layers have plenty of time to cool without the AUX helping.
I tried all fans off on the bowl to check that, also slowed up the print speed to that layer step and it was unchanged. I ran outside wall first a few times. I didn’t tried another slicer at the time as I had to get the stuff done.
The default elephant foot compensation is only 0.15 mm and for the 1st layer. So set it to “0” will only the 1st layer enhance by around 0.15 mm / 0.3 mm (both sides) but the measurement shows, that the shrinkage is around 1 mm over all vase bottom layers. So I think this will not work.
