I come back on the small details with precision issue.
When trying to deposit filament of size MUCH smaller than the nozzle itself ( less than 0.5 for a 0.5 nozzle) I think there is no exact way for the printer to ensure where the plastic will be put.
On the left you see the nozzle, and the smaller filament can be dropped in any position between the dotted vertical lines corresponding to the 0.5 nozzle hole. Of course the ideal output would be as the straight “ideal” picture, being able to do perfect circles, but at those very small sizes, realistically it is more probable to have the “realistic” picture, that produce the “all but not a perfect circle” showed.
On the right, you can see the perfect straight ZIG-ZAG for a 0.5 extrusion (in yellow) , and the smaller extrusion path, not squared zig zag any more (in green) and the ideal (in blue).
So I think in order to do precise fine details it is a must to have a 0.2/0.3 nozzle or a dual extruded, same material different nozzle sizes.
What do you think ? Do you agree with this analysis ?
I think for lower resoultions than the nozzle size, the nozzle is pushing the material on top of the previous layer, so the effect should be less random as it does not fall freely.
Not an expert in materials behaviour, anyway…
It’s not that the material comes out in a thinner stream, but rather gets pulled out at nozzle with and then stretched with a various thickness due individual and momentary effects.
Extruding speed, temrperature and length also plays a major role. I print .2 and .3 layers with a .5 nozzle and am quite happy. With low speed and lots of retraction combined with low temperature I experienced a lot of blobbing and irregular layer dimensions. Heating up more and trying to extrude as much as possible in one go that problem has been reduced significantly. Bridging however remains problematic. But some slicers have options for that (bridge with .4 but print the rest with .2 etc)
Don’t confuse the layer thickness with the layer width. A layer can be 0.1 in thickness (e.g. pushed and spread by the nozzle) but if the required width should be 0.1 either, then you will have the imprecisions of the picture. All the samples are referring on a view by top, keeping in mind that the width is approximate and random, an not the layer height, that is correct because the filament is spread by the nozzle.
I agree with your assessment @Roberto_Coli . It is less than ideal for the filament to be smaller than the bore of the extruder. Ideally, if you did have a filament that was smaller, the extruder could collect melted material until it could extrude the size of the bore. That would eliminate any benefit of having a smaller filament size though.
If you want more precision by having a smaller extruded filament size, then having the extruder nozzle bore size be the smaller 0.2/0.3 would be best. Otherwise, you will end up with results similar to your images.
If I am not mistaken, some text books suggest a minimum width of (0.7 * noodle ∅). @Hans_Franke described the situation as it is. And that is exactly the reason why one should not print traces thinner the formula above.
I’d only add that extrusion precision for both layer height (which is not the topic of this post) and trace width, might be improved be means of:
• again, the diameter of the noozle;
• filament diameter (1.75 offers better control over 3 mm);
• bowden vs. direct/geared cold end (geared being the best solution);
• transition zone length (from T to Te, extrusion temperature, the shorter the better);
• some more factors that I won’t take the time to mention since I am about to have lunch and I’m starving!
@Marco_Alici have you actually measured a single wall to be less than the diameter of your nozzle? You’re probably actually making .5+mm traces and just telling your slicer that it’s .4, which causes it to pack them closer together. This could be correcting for another issue in your machine.
