How to get rid of thoes things?

[janis12 0]

Hi and Hello!

Does anyone know how to get rid of thoes imperfections?

In my opinion nozzle stays for a bit to long in that spot before going to next letter.
Any sugestions?  

Letter dimensions: Height 2.7mm Width 0.45mm
Print settings:

Nozzle dimension - 0.4mm

Layer width - 0.4mm

Layer height - 0.2mm

[GregValiant 1,251]

We'll ask @geert_2 but I'm going to guess first...

I'm guessing you need to cool down a bit, increase your retraction speed and if you are using Z-hops then increase the Z speed (and maybe distance) as well.  That lettering is far from terrible.

You can actually enter whatever you want as speeds in Cura.  M203 in your printer will be the real speed limiter.  You could make an adjustment to it by printing a short gcode file of:

M203 X500 Y500 Z25 E25 ;Maximum feedrates

M500 ; save settings

Some printer definitions have very low Z and E speeds set in M203.  I would guess that the printers were checked by the manufacturer and the defined speeds are what they can handle so adjust them at your own peril.  Speed is also affected by the acceleration on each axis.

Cura's maximum speeds, acceleration, and jerk are located in the Printer Settings which loads from the Marketplace.  The maximums defined there become the maximums that the boxes in the Speed section (of the Cura settings) will allow.

[FRabe 5]

This just looks like the nozzle is too hot, or possibly even worn out, causing over-extrusion. If you have not modified extrusion settings in Cura, some settings to look into turning on would be "Optimize Wall Printing Order", and "Compensate Wall Overlaps", both found in the walls section.

 

@janis12, what material are you using and what temperature are you using for the nozzle? How long has the nozzle been in use? Have you printed any abrasive filaments with this nozzle (CF added, metal added, glow-in-the-dark, etc.)? How many walls are you using in your settings? Print speed?

 

The answers to those questions may just lead to more questions, but with over-extrusion they are where I would start.

 

Edit*

 

I just noticed that you said the letters are only supposed to be 0.45mm in width. This happens to be just over your wall width, meaning that the printer will print 2 widths of your nozzle. Try to print letters at 0.4mm width or 0.8mm width and see if this gives more consistent lettering. You may not have over-extrusion at all, and it is just a matter of wall settings vs the model. An easy way to do this would be to scale to 88% (this should give under 0.4mm width on your letters, so it only prints one wall).

Edited August 20, 2021 by FRabe
more insight

[geert_2 557]

I have seen this too in my small letterings. Upon reaching the end of a text-leg, the printer stops for a brief moment, does a retraction, and only then moves to the next letter. It is that short stop that seems to cause this little blob. Printing very slow, cool and in thin layers reduces the effect, but I could not get totally rid of it. I never tried playing with other settings (acceleration etc.), so I don't know their effect, if any. But I can live with this sort of defects, I consider it production-method limitations, similar to parting lines, ejector pin marks, and injector nozzle marks in injection moulded parts.

 

For a 0.4mm nozzle printer, designing letters with exactly 0.4mm wide legs did not work well in my tests. In curved segments the real line-width could vary between maybe 0.39mm and 0.41mm, due to the STL-triangles (=straight lines) instead of smooth curves. So, parts of the text tended to fall away, when smaller than 0.40mm. Now I usually design my text on a 0.5mm grid, or a 0.25mm grid but then use 2 blocks to get 0.5mm wide legs, and 0.35mm caps height.

 

These characters are printed at normal speeds of 50mm/s and 0.1mm layer height, so quite visible blobs indeed: