0’025mm layer height tests aborted. I think it works + or -, but my extruder hasn’t got enough resolution for maintain a so small plastic flow constantly. It extrudes spurts each time, they are even visible on the last printed layer.
Maybe a 0’25mm nozzle instead of a 0’4mm one may help? And/or a 1/32 microstepper like the DRV8825 instead of my 1/16 A4988?
I’m going to try increasing the perimeters extrusin width in Slic3r to force a bit more flow, maybe it works…
Perhaps a 0.1mm nozzle from @Jerrill_Johnson and a planetary reduction gear on the extruder?
But… Doesn’t the planetary reduction limit the speed? I currently have a 5.22:1 reduction with gears, maybe more reduction leads to that. I haven’t tried.
On the other hand, I haven’t seen a 0.1mm nozzle before, I’m using the E3D v5 hot-end and they only sell 0.25, 0.4 and 0.5 nozzles.
Yes, it would. The point being that a higher reduction will let you meter out more precisely.
@Samuel_Ureta all extruders have a minimum reliable volumetric flow rate, there is a chance you are hitting it at that layer height.
If that’s the case, a smaller nozzle may not help.
Your options also include :
-A wider nozzle (thus higher flow rate for same layer height)
-Increase your speed
A higher resolution stepper might help but if the minimum flow rate is limited by friction in the nozzle or some other factor it may not help.
How is your temperature? It might be a too high temp. Or moist in your fillament. Gas forms in the nozzle and spurts out plastic.
@Mano_Biletsky_Open_M I usually print this PLA at 205ºC but for this test I have turned it down to 195ºC. I’ll try even less.
@Tim_Rastall so, if I have understood it right, with a wider nozzle diameter, the same motor movement would lead to a shorter but wider output filament, right? So for doing the same perimeter the motor would make more microsteps and the spurts would be + or - removed, am I right? And maybe the only bad thing about that would be fatter perimeters, a bit less accuracy.
After all this, will a planetary reduction help as @Joseph_Chiu suggested?
Can you explain a bit more that “friction in the nozzle” thing?
Thank you very much you all, guys.
Recommended temperature for pla is 185’celsius.
@Samuel_Ureta well, I can try 
. As far as I understand it, the viscosity of the molten plastic exhibits a certain resistance to being forced through that tiny nozzle, so at very low extrusion rates, that resistance prevents the extrudiate leaving the nozzle until sufficient pressure is built up behind the molten plastic, at which point extrusion occurs, once the excess pressure is alleviated, the cycle starts again. I think this is something to do with laminar flow but my fluid dynamics learnings were 15 years ago so its probably best not to take my word for it.
What are your current steps/mm? My current direct drive/planetary set up runs around 760 s/mm. I am very interested in testing this myself. Another theory that has been talked about is using smaller diameter filament (1.75mm) for low layer height. Reducing the diameter of the filament would require an increase in revolutions to achieve the same extruded volume if using 3.0mm filament.
Try Cura, I can do 20 microns on my Ultimaker 1 and Ultimaker 2. not very useful for me but doable if you need it. Certainly should adjust temp and material flow for such a fine resolution, I just don’t need it.
