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Inside wall adhesion problem with Cura 3.0.3 for mac

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Hi all,

I'm encountering an issue with Cura 3.0.3 for mac whereby inner walls do not properly adhere. I've been able to test the same file on both Cura 3.0.3 for Mac and Cura 15 for Windows. Only on 3.0.3 for mac does the problem occur. This issue aside, the print quality is otherwise good.

Rather than try and explain the problem in further detail, I'm including photos both with the problem and without. The printer is a Prusa i3 and I'm using reprap flavour gcode.

First of all, here is the first several layers of a print using the cura 15 on windows, with no issues. Take note of the quality around the hole in the base. It's all good.

img

The next three photos demonstrate the issue.

img

img

img

Note the lack of adhesion of the inner walls around the holes in the base to the rest of the print. It's actually possible to pop out these walls.

Edited by Guest

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It's underextruding. Since I assume your printer hasn't changed from one print to the next it can only be one of these things:

print temp

print speeds

layer height

nozzle width

Look at the old print job from cura 15 and write down the above 4 values and then set ALL the print temps, ALL the printing speeds, layer height and ALL the nozzle widths to what it was in cura 15 and see if that fixes it. If it does then please undo the changes one at a time and let us know which problem it was. The Cura team needs feedback on stuff like this (bad slicer defaults that lead to underextrusion).

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It's underextruding.  Since I assume your printer hasn't changed from one print to the next it can only be one of these things:

print temp

print speeds

layer height

nozzle width

Look at the old print job from cura 15 and write down the above 4 values and then set ALL the print temps, ALL the printing speeds, layer height and ALL the nozzle widths to what it was in cura 15 and see if that fixes it.  If it does then please undo the changes one at a time and let us know which problem it was.  The Cura team needs feedback on stuff like this (bad slicer defaults that lead to underextrusion).

@gr5 thanks for this. I'm going through these settings and have so far noticed one discrepancy. My wall speeds were set to 45 mm/s, and only 20 mm/s on windows. Reducing to 20 has made an improvement - visually there are no longer the gaps that I was seeing previously.

However, the print quality is still significantly stronger on the windows print. The walls can still pop out on the mac print, but not the windows one.

Here's 2 images of the latest print. I'll continue to look through the settings.

https://www.dropbox.com/s/5dvncpzbc3k9k3h/FIX-ATTEMPT1-1.jpeg

https://www.dropbox.com/s/1lq2iwcu5qzwz19/FIX-ATTEMPT1-2.jpeg

Regarding defaults, I previously found that having z hop disabled by default caused a fair amount of issues, but I've no idea whether there are good reasons for that being set so.

Edited by Guest

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zhop is probably unrelated to any of this. This is different from "retract at layer change".

Check all the other line width settings and shell width. I like to make line width equal to nozzle width (e.g. typically 0.4mm) and shell width *always* a multiple of that (e.g. 1.2mm). Cura likes to make shell width 1mm and do one line at .6mm and one at .4mm or do two at .35mm and one at .3mm. It's a mess. I think it's better to stick with one size so that you don't have this adjustment period while the nozzle pressure returns to steady state.

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@gr5 I undertand z-hop is unrelated to this issue - just thought I'd bring that up on the topic of problematic defaults.

Line widths & layer heights seem to be set correctly. I've tweaked a couple of things that didn't quite match the windows settings (namely the no. of of top/bottom layers & min layer time) and will give it another shot when the time allows.

Some cura settings:

https://www.dropbox.com/s/5z79v7rg9gn6w9j/cura-settings.png

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So 0.3mm layer height is quite thick for a .4mm nozzle. I would seriously consider printing this with a .8mm or larger nozzle.

If you multiply these 2 numbers and also multiply by speed in mm/sec you get the volume per second. so for example 100mm/sec print speed X .3 X .4 gives you 12mm^3/sec which is too fast for a UM printer. Even if you heat PLA to 240C nozzle temp such that the PLA is less viscous - that's a difficult speed to print at with such a small nozzle. I wouldn't go over 30mm/sec with that thick layer height. Otherwise you will likely get some underextrusion.

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So 0.3mm layer height is quite thick for a .4mm nozzle.  I would seriously consider printing this with a .8mm or larger nozzle.

If you multiply these 2 numbers and also multiply by speed in mm/sec you get the volume per second.  so for example 100mm/sec print speed X .3 X .4 gives you 12mm^3/sec which is too fast for a UM printer.  Even if you heat PLA to 240C nozzle temp such that the PLA is less viscous - that's a difficult speed to print at with such a small nozzle.  I wouldn't go over 30mm/sec with that thick layer height.  Otherwise you will likely get some underextrusion.

Understood - I'm currently printing with speed set to 30 mm/s (see speed settings here: https://www.dropbox.com/s/liimvdpu7fwnobc/PROBLEM-3.jpg ) although I may lower it to experiment. Let me know if anything else there looks off. Noted your advice regarding nozzle size. Much appreciated.

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