Wow, thanks for all the tips. Arachne walls, number of walls and reduced line width didn’t have any impact that I could notice. However, switching inner/outer made a big difference. From another comment I also played with the elephant foot settings but while that helped a bit, I found it too finnicky to get right. However, that tip helped me figure out my final solution.
What I ended up doing was:
- Swapping inner/outer – thanks superLight
- Making the hole slightly larger – thanks Ukdavewood
- I changed the design to add a 0.25mm fillet to the bottom side (inspired by the elephant’s foot suggestion from Uhl and the fillet idea from Wsquared58).
- Setting small perimeters to 20% speed
- Globally I turned off reduce infill retraction
Doing this, a 1 mm hole results in a 0.6 mm hole that is clear all the way through a 1.5 mm thick panel which is close enough for my application. I also tried this same approach on a sample with even smaller holes and while I didn’t measure them accurately, I would guess they are as small as 0.25-0.3 mm and clear through.
While I feel that the octagon solution (thanks zentenro) is an excellent idea I did not try it due to the sheer number of holes I have (100+).
As a side note I wish you could set the inner/outer setting using a modifier because switching this setting on the entire model gave me a different problem where the outer wall of the object (which has a 2.5 mm fillet) failed on the overhanging edge, so I sliced the outer “wall” off my object in Fusion and just printed them as separate pieces aligned together. That way I can have outer/inner for the holes and inner/outer for the slight overhang on the object’s outer edge.