As you might expect, changing the layer thickness to 0.1 mm = 100 μm dramatically improves the appearance of the dummy 9 mm Luger bullet on the left, compared to the 0.25 mm = 250 μm layers on the right:
The inside edge of the translucent skirt around the quartet measured 90 to 110 μm, so the layer height is spot on:
That required no adjustments to the M2 at all; It Just Works. Admittedly, that’s with a custom platform and firm supports replacing the springs, plus better Z-axis homing, but the overall structure was fine to start with.
I used the same Slic3r settings as before, with the only change being the layer thickness. Letting it pick the layer width might produce better results, but a 0.35 mm nozzle won’t go much narrower than 0.40 mm anyway.
A closer look at the bullet show the thinner layers provide a better rendition of the stretched sphere forming the nose; it’s less pointy than the one assembled from thicker layers:
The nose closes better with thinner layers:
None of that really matters for this application, but it’s a useful data point.
The downside is that printing with thinner layers requires more time: a single bullet (of 16) requires 2.2 minutes at 250 μm and (of 4) 9 minutes at 100 μm. The simple ratio of layer thicknesses predicts a factor of 2.5, not 4, but the skirt requires a larger fraction of the total time. The estimated time for a 4×4 array at 100 μm comes out at 5.2 minutes each, a factor of 2.4, which is close enough.
Although 100 μm certainly looks better, it doesn’t really improve anything for most of the blocky stuff I make…