Poor overhang quality

Thought I’d post this here as I believe this would affect both P1P and X1C printers.
I’ve been struggling to get a decent finish on this overhanging piece. (printed upright, oriented as in the first pic)
0.4 nozzle, 0.20 layer heights.
This is the best it has looked, after slowing down the outer wall and infill to 30mm/s. I also have slow down for overhangs enabled, with 30, 20, 10 mm/s settings. I also reduced the percentage of cooling to 10% of line width with 90% cooling fan. This is for PETG.
Other tries have resulted in a worse finish, slowing down the outer perimeter speed seems to have produced the best results but the model took 4 x as long to print. Apart from reducing the layer height, are there any other settings that t you’ve found has helped a lot? This shouldn’t be too much overhang degree for the printer to handle without supports. As you can see it improves higher up, the larger the overall surface area becomes but the angle hasn’t changed.
I have a feeling this is a case of the part cooling fan not being able to keep up but keen to hear other people’s fixes.
Note, I have a P1P and do not have the auxiliary part cooling fan.


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You could try to rotate the object a bit around the z axis so that it starts printing diagonally. That could let the part cooling fan cover more area.

Btw. you can retrofit the aux fan on the P1P quite easily. I’ve done that, but don’t expect too much from it, since it is only cooling from one side. Orientation becomes more important that way.

Thanks, I like your idea of rotating 45° to give more area. I’ve only tried it 180° from the auto rotation and that was more so I could easily see if it was improving with different setting changes.
Yes, I know about the auxillary fan. I did have it installed but found it often made PLA prints worse and wasn’t used for the majority of my filaments (PETG, ABS, ASA), so I re-purposed the fan for an air filter/scrubber on the other side.

I cannot tell the angle of the overhang. Overhangs usually print fine up to 45 degrees without support. After that, cooling might not be enough.

Make sure your print order is inner then outer perimeters. That gives the overhang more to “hang on” to.

Thanks, the angle is ~40 degrees and yes order is inner first. The finish is fine further up where the cross section is larger, just not good it seems where the layers don’t have as much time to cool. I think the only real solution would be to reduce the layer height to 0.16 and run at normal speed, rather than 0.20 slowed down.