Printed parts have "boat" shape towards edges (not warping)

[Darkmind]

Hi guys,

I hope someone can give me some advice as all my search so far brings me to plastic warping theme which is not the case.

The problem I have is that every time, I try to print some sharp edges (like 90 degrees or a straight line) or a tall object - the part starts to get exactly the shape of a canoe boat (straight in the middle, but the edges are up). The reason I'm saying that it's not the famous warping problem or adhesion to the heatbed is because the bottom layer prints ideally and sticks very well to the bed.

Please, see the attached photos where I try to print just a 2x2cm rectangle with a 1x1cm whole inside:
The grey PLA plastic was the 3m sample supplied with the kit - that one printed more or less fine, without even any calibration
The yellow PLA plastic is 1kg roll from Geeetech - you see that the walls are not vertical anymore, shrinking towards the top layer and most important - notice the "teeth" at the top edges on each corner
The black PLA plastic is some noname which I bought for my 3d pen - it behaves the same as yellow

You see that that bottom layer has no warping. The warping starts towards the top layer

The other photo shows the sample Ultimaker bot. Its feet printed ideally, because they don't have sharp edges (they are rounded and printed as solid line, without the extruder changing direction sharply). However, towards the top all layers get the form of a dish (see the arms for example).

I've already tried playing with extruder temperature (tried 195-220), played with heatbed temperature (tried 50-80, giving enough time to heat the top glass). I calibrated all axis including extruder (using calipers). I tried different plastics as I mentioned. I tried 0.2mm and 0.1mm layers. I leveled the heatbed and played with extruder height.

This issue causes lots of problems as for example the printed bot looks messy. Also, every time there's a slim wall that needs to be printed - extruder crashes into these edges and eventually detaches the part from the bed.

Is there anything else that can cause this kind of issues? It seems like on sharp direction changes of the nozzle the plastic tends to follow it

UPD: ah, yeah, and I played with print speed (print: 46mm/s, outer perimeter: 39, infill: 46)

[William]

Hi,it looks like it's caused by overheating.
You can increase the fan power, or reduce the temperature appropriately.
For details, please refer to this link:
https://www.simplify3d.com/support/prin ... verriding/

[Darkmind]

The link gives 404

By fan you mean the cooling one? (for the nozzle, not the cooler for extruder that was provided out of the box)

I forgot to mention in the post that as of now I don't have a separate cooling fan (already ordered)

[William]

Hi,It's the fan that cools the nozzle.We call it a blower.