rough corners and unstable overhang test

[lht1ove 0]

Hi. I've just bought UM2C, and I have some troubles testing the printer

First, It often makes rough corners. (layers don't bond well)

Second, I tried some overhang angle test, but quality is kinda sus

 

Here are some pictures about these problems..

 

I tried changing nozzle and heatbed temperature, print speed, and etc... But these troubles still remains

Please help me..🥺 Thanks.

 

(im using ultimaker PLA)

Edited July 28, 2021 by lht1ove

[Smithy 1,144]

Do you use a default profile like the "Normal" one or something else?

What't the temperature in the room you print? Do you have the printer enclosed?

[lht1ove 0]

7 minutes ago, Smithy said:

Do you use a default profile like the "Normal" one or something else?

What't the temperature in the room you print? Do you have the printer enclosed?

I tried fine, normal, draft quality and temperature in the room is constant but sometimes changed by air conditioner. But as I use air manager, I think that temperature in the room doesn't really matter;

[SandervG 1,521]

Hello, if you wanted to test overhangs I probably wouldn't try the draft model, it is tailored to printing fast and that probably won't give you the best results. What you could try is print two of these overhang tests at the same time, so when the print head is printing one, the other one has time to cool down. What you see on the second picture is that the previous layers have not cooled down yet and are therefor still soft, and don't properly support the next extruded layer yet. They might get pushed down under the pressure of the extruded layer, giving more room for the next layer to 'expand', and that is how you get such a lifting corner.

So the layers need time to cool down, you can do this by printing two at the same time, not too high of a temperature, make sure your fan is running at a good speed and a thin layer is probably better because it will cool down faster than a thick layer. Hope this helps! But I don't think you should expect smooth bottom surface on an overhang as shown on the last picture, that seems quite extreme. And I'm not sure what I'm looking at on the first picture. 

 

Have a great day! 

[geert_2 557]

As said above, the curling up appears to be due to insufficient cooling. On small areas, the hot nozzle stays on top of the part, so it can not cool and not solidify. So the nozzle is sort of "wading through hot mud", instead of printing on top of a solid area. Printing a dummy tower next to it, helps, but does not eliminate the problem.

 

For overhangs, I found that printing in thicker layers makes them curl up less. Here too: it reduces the effect, but does not eliminate it. On overhangs, the freshly applied material is hanging partly in the air, and it has no or very little support from below. So it is subject to both sagging (gravity) and curling up (shrinking while cooling) at the same time.

 

Try printing on the coolest edge of the temp-range. (At least, if that doesn't affect the rest of the print, else you need to prioritize.)

 

 

[lht1ove 0]

Thanks for help!