Gaps in inner walls

[Gotbread]

Hello,

i'm trying to debug a weird issue with my printer (Flash Forge Creator Pro):

As you see, inner holes look horrible and are very weak. the walls of the hole have gaps.
Strangely, this does not happen with outside walls as you can see.

Also, while the print is building up, this problem happens in EVERY layer, so even
there the hole-walls dont really touch.

This only happend after i switched filament brands, i'm currently using this one:
https://www.dasfilament.de/filament-ref ... fill-850-g

I have tried overextrusion and outline overlap. This did not seem to help.
I tried with different temperatures, no results. Nozzle has been cleaned, PTFE tube looked okay.
I did a flow rate calibration test, result looked fine as well (i bumped up the extrusion to 106%
after this test).

Anyone an idea of whats going on here?

I also hypothesized that since all these holes require a long travel distance to get to,
maybe due to retraction not enough filament is coming out. So i made a test with
5 models and 5 processes, each one with a different retraction extra restart distance,
to extrude more filament after the restart.

As you can see, it did not help, but the blobs in the holes are getting bigger from bottom
to top. Strangely enough this time the inner walls aka holes turned out very nice.

It seems that holes/walls after a long travel behave differently than after a short travel?

Factory file is attached. I printed with PLA/medium settings.

[S3D-Jake]

The solution to these types of gaps is almost always the same. Print infill slower and adjust your outline overlap setting in the infill tab. Your outline overlap is already 40%, So i'd keep that where it is for now. Your infill % being 12 might also be an issue in general. I'd start by decreasing your default print speed from 3000 mm/min to something like 2400-2600 mm/min.

https://www.simplify3d.com/support/prin ... d-outline/

[Gotbread]

I tried reducing the speed, but it did not seem to make a difference. In steps i went all the way down to 60%
(1800mm/min), still no change. This is how it looks like:

This is mid-print and during the first few layers. So the infill is 100%.
Still the external walls look good, but the internal hole is seriously underextruded, on each layer.

I dont think it has anything to do with the infill as the hole should count as perimeter, right?

What i dont understand is why external perimeters come out differently than the internal
perimeters.