Anyone printing with 0.8mm nozzle on stock hotend on Prusa MK3S+ ?
 
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Anyone printing with 0.8mm nozzle on stock hotend on Prusa MK3S+ ?  

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petesurfer
(@petesurfer)
Eminent Member
Anyone printing with 0.8mm nozzle on stock hotend on Prusa MK3S+ ?

Hello, I'm printing with a 0.8mm nozzle on Prusa MK3S+, with the stock hot end. 
I have two issues:

1) I'm getting random blobs and imperfections in the printed piece, as shown below in red

2) Although the printing goes well (if we forget about the mentioned blobs and imperfections), the hot end's fan makes more than usual.

Are these two things normal? I'm using prusa slicer's default configuration for 0.8mm nozzles to avoid making mistakes with the slicer parameters. I understand that if it has to heat more plastic the hot end will get hotter and will need higher ventilation from the fan, producing more noise...but to what extents? 

Anyone had similar results?, or if better (could you give me any tips please?). I'm using Prusa's official filament, Prusament, just to be safe on that side.

Many thanks!
Pedro

Opublikowany : 21/07/2023 9:27 am
beegmouse
(@beegmouse)
Eminent Member
RE: Anyone printing with 0.8mm nozzle on stock hotend on Prusa MK3S+ ?

That is about the level of quality I would expect from an 0.8mm nozzle.

Doubling your nozzle size, quadruples your required flow and quadruples the effect of flow related errors.

And because your layer heights increase, one error on one layer becomes far more noticable to the naked eye.

Lumps can be caused by water in damp filament boiling and at the start/stop of an extrusion.

 

Opublikowany : 01/08/2023 12:29 pm
Thejiral
(@thejiral)
Noble Member
RE: Anyone printing with 0.8mm nozzle on stock hotend on Prusa MK3S+ ?

Have you checked the max flow rate your printer/hotend can manage before underextrusion becomes an issue due to insufficient heat transfer into the filament?
Like beegmouse said, a 0.8 mm nozzle leads to much higher flow rates and you can very easily push past the capabilities of the stock hotend that way. 

There is a flow rate calibration file on printables from CNC kitchen. I would use that to determine the max flow rate in your system and then to calculate the max print speed you can manage with a 0.8 mm nozzle with your filament on your system and subsequently stay below that. 

Mk3s MMU2s, Voron 0.1, Voron 2.4

Opublikowany : 01/08/2023 12:53 pm
petesurfer
(@petesurfer)
Eminent Member
Topic starter answered:
RE: Anyone printing with 0.8mm nozzle on stock hotend on Prusa MK3S+ ?

Thank you very much @Thejiral and @beegmouse for your feedback! I will definitely try the calibration file you mention to see what flow rate and speed I can manage. 

Opublikowany : 01/08/2023 1:01 pm
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