Slic3r extrusion under 0.4 mm with 0.4 mm nozzle  

Re: Slic3r extrusion under 0.4 mm with 0.4 mm nozzle

Hi All! I know that the rule says that for a 0.4mm nozzle extrusion width for should be between 0.4 and 0.5 mm, but I find that using extrusion width of 0.2 mm and 50% speed for the top layer give a much better result than the standard settings. Anyone else with a similar experience?

Stock settings should give you smooth results, even on top layer.
You are underextruding so maybe your extrusion multiplier is > than 1, check your extrusion multiplier and calibrate your extruder first.
You should not use less than 0.4mm extrusion width, from 0.4 to 0.7 is ok

Re: Slic3r extrusion under 0.4 mm with 0.4 mm nozzle

The problem with using a thin extrusion width is that, depending on your layer height, you may be printing your filament as a cylinder rather than the optimal squished oval. This will lead to poor layer adhesion. If it works for you, go for it, but be aware there are reasons for the common guidelines. You generally want the layer height lower than the extrusion width.

If you're really after a smooth top layer, try using Cura and the experimental ironing feature. It makes a pass with narrow widths and very little extrusion to finish the top layer. It looks great, but it is slow. Probably no slower than what you're doing though. Cura has a lot of other finish-oriented features that you might like.

Finish is a very subjective thing, so there's nothing wrong with experimentation. Have fun and put up some pics of your results.