On their website they say the following

0.25 mm nozzle: 150 to 60 micron
0.40 mm nozzle: 200 to 20 micron
0.60 mm nozzle: 400 to 20 micron
0.80 mm nozzle: 600 to 20 micron

That confuses me. Why can I go down to 20 micron with the 0.40, 0.60 and 0.80 nozzle but only down to 60 micron with the much smaller 0.25 nozzle? Is that a typo and should say 6 micron?

  • $\begingroup$ Have you found & fixed the problem? If any of the answers helped you to get an answer to your question or come to your own conclusions then please do vote & accept an answer (using the tick button next to it). This helps us reduce the unanswered questions list & stops the question from being bumped once in a while. If you found another answer (than those already posted), please add that answer (& accept after 48 hours) to share your experience with the community. If you have not been able to address the problem please update your question. $\endgroup$ – 0scar Sep 11 '18 at 21:06

You need a certain minimum flow rate to achieve consistent extrusion. Flow rate is the product of print speed, extrusion width (proportional to nozzle size) and print speed. If you use a very small nozzle and very low layer height, you'd need a very high printing speed to achieve a reasonable flow rate. Therefore, it's quite possible this is not a mistake and intentional.

Keep in mind that Ultimaker uses 2.85mm filament. With a 0.3mm extrusion width, 0.02mm layer height and 60mm/s print speed, you would need a feedrate of 0.06mm/s into your extruder. The extruder might not be able to develop enough force on the filament at such a low speed (which, owing to the small nozzle size, requires a relatively large amount of force).

The ultimaker can not print 6 micron layers since the smallest increment the Z-axis can move in is 5 microns. 6 microns is not a multiple of that.

| improve this answer | |
  • $\begingroup$ I would say that extruder force is not an issue. However, accuracy is, since 0.06 mm/s means a very limited number of steps: assuming 3:1 gear ratio and (very approximately) 4 mm hobb bolt radius, we are talking of about 2.5°/s on the stepper motor: 1.5 steps per second. Microstepping brings it to 24 steps/s, but microstepping are not always very accurate and the position of the axis may lag easily several microsteps on an extruder, resulting in inconsistent extrusion. $\endgroup$ – FarO Jan 8 at 16:12

In addition of Tom van der Zanden's answer, when the filament moves too slowly through the heated part of the printhead it is very likeley to clog.

I have had this multiple times on my UM1+, most of the time resulting from a heated printhead with no extrusion (before or after prints). So you need to be sure to have a minimum of filament extrusion happening, wich is most likeley not the case when having 0.25mm * 20 micron instead of 0.60mm * 20micron, for example.

You could of course make the printhead move faster, resulting in a higher extrusion, but that will lower the print quality again.

But let me tell you this: Always look out for high extrusion, removing clogs is a real pain!

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.