Arachne is insanely useful when printing with a nozzle bigger than 0.4, looking up other topics about arachne there are still a lof of issues apparently. In my testing with a 0.6 nozzle and the standard 0.3 mm profile prints presents a lot of tiny holes on small walls.
Not sure if there is a question in there but there is not enough information to help you since you did not post any settings you have tweaked or tried or anything. The times i see this is when you are printing with ARchane and a Zhop retraction issue since you are printing with a lower extrusion the pressure does change inside the nozzle which can cause oozing, blobs and sometimes missing filament when it cannot start back up fast enough and build pressure.
When printing such small objects like that image you posted i turn off zhop and retractions to very low or none this solves most but you will have to play around with such settings to suit your part that you are printing.
If this is a test print dont spend too much time on this its a rabbit hole you will not climb out of. if this is an object you are printing a ton of then go thru the process of tunning for it but only if you really need to.
Since settings that change or fixes this can cause issues on other parts it a balancing game.
It’s the standard 0.3 preset from bambustudio 0.6 nozzle. I didn’t change anything but seam alignment to back. No z-hop.
These holes are not in the retraction position, should I try to lower retraction nonetheless?
The retraction on the default 0.6mm profile is WAY too high, you can tone it down to something like 0.6mm and it should be fine.
It’s not AT the retraction point, but caused by bubbles of air sucked into the nozzle.
This doens’t explain why with the same nozzle settings Classic walls show no holes. See pictures below. With Classic there are some wierd layer steps, as you can see. That’s the main reason I wanted to switch to Arachne.
These steps are exactly at speed change layer and infill change layers.
(scheme color: speed)
0.4 nozzle 0.2 / 0.28 profile didn’t show any wierd steps like this.