part cooling issues?  

Re: part cooling issues?

What you are seeing is in the normal range, and difficult to lessen.

Look here: (look at the chamfer part)
https://rigid.ink/blogs/news/how-to-print-overhangs-bridges-and-exceeding-the-45-rule

Things like rounded upwards corners are impossible to print cleanly because they exceed the 45 degree angle rule.

Things that will make it better:
- print in 0.35 layer height: bigger layers will show this effect less because fatter layers will grip more onto the edge of the previous layer.
- print very slow: print at 50% or even 30% speed while using 100% of the fan will make those extreme overhangs look a bit better. That's because there is insufficient cooling when printing at 100% speed. Rotate the display know while its printing to slow/speed up the print moves, fan speed will stay the same.
- print in material that doesn't curl so much: PLA and ABS are notorious for curling, other stuff like PETG will not curl upwards so much. If you print the thing with PETG (240 degrees, 100% fan, 50% speed), things will look a lot better.
- not everything can be printed cleanly. post processing is often necessary.
- clean the nozzle. If there is some debris in the nozzle you need to do a few cold pulls.
debris in the nozzle can cause these overhangs, because it's not going straight down from the nozzle opening. release the idler, warm up the hotend to 220 degrees, push the filament through per hand. Is it coming out slightly sideways instead of straight down? then there's burned debris from previous filament in the nozzle. cold pulling or using a new nozzle will give you a bit better overhangs and outer layer lines.

Also the first thing anyone suggests is "print with with a lower temperature", yes this works to some degree, too, but leads to a lot of extrusion issues on the MK3. The closer you get to 200 degrees with PLA, the faster it will randomly clog. You'd need a geared extruder like the E3D Titan to force filament through the nozzle.

Re: part cooling issues?

What you are seeing is in the normal range, and difficult to lessen.

Look here: (look at the chamfer part)
https://rigid.ink/blogs/news/how-to-print-overhangs-bridges-and-exceeding-the-45-rule

Things like rounded upwards corners are impossible to print cleanly because they exceed the 45 degree angle rule.

Things that will make it better:
- print in 0.35 layer height: bigger layers will show this effect less because fatter layers will grip more onto the edge of the previous layer.
- print very slow: print at 50% or even 30% speed while using 100% of the fan will make those extreme overhangs look a bit better. That's because there is insufficient cooling when printing at 100% speed. Rotate the display know while its printing to slow/speed up the print moves, fan speed will stay the same.
- print in material that doesn't curl so much: PLA and ABS are notorious for curling, other stuff like PETG will not curl upwards so much. If you print the thing with PETG (240 degrees, 100% fan, 50% speed), things will look a lot better.
- not everything can be printed cleanly. post processing is often necessary.
- clean the nozzle. If there is some debris in the nozzle you need to do a few cold pulls.
debris in the nozzle can cause these overhangs, because it's not going straight down from the nozzle opening. release the idler, warm up the hotend to 220 degrees, push the filament through per hand. Is it coming out slightly sideways instead of straight down? then there's burned debris from previous filament in the nozzle. cold pulling or using a new nozzle will give you a bit better overhangs and outer layer lines.

Also the first thing anyone suggests is "print with with a lower temperature", yes this works to some degree, too, but leads to a lot of extrusion issues on the MK3. The closer you get to 200 degrees with PLA, the faster it will randomly clog. You'd need a geared extruder like the E3D Titan to force filament through the nozzle.

That's a bit disappointing...

- I'd rather not print at a bigger layer height, i find it to be quite coarse for what I want to do as it is.
- I am printing at 50% now, we'll see how that goes.
- I have printed the calicat in PET-G as well, and while it is a bit better, it isn't a lot better.
- it's a brand new Prusa MK3, but I have cleaned the nozzle with the needle, and when I extrude manually, it comes out straight. I don't know how to do a cold pull?

I should add that on some sides of the calicat it prints almost perfect, and on other sides it doesn't...

I have tried prusacontrol, slic3r, and cura, but I prefer cura generally. Is there a way in cura to make printing slow down on overhangs / edges, and keep the speed the 100% on other parts?

I'm quite new at this as this is my first printer, and the kit arrived 2 weeks ago.

Thanks!

Re: part cooling issues?

If you've got no issues with extrusion don't bother with cold pulls.

Second question; not that i know of.

Re: part cooling issues?

so printing at 50% makes it better, if not completely solved.

I guess i should look into better part cooling? dno how to do that on a new prusa mk3... and i guess set my slicer to print certain parts slower...

Any other things I can do?

Re: part cooling issues?

change slicer which puts less material near sloped walls, this helps a lot
print slower to give time for cooling fan to cool down material, turn bed off for PLA because air is heated by bed, then hot air is pulled by the blower
change cooling nozzle but it's not helping much
lower extruder multiplier to extrude less material, because les material cools faster

experiment and check what is working for you
I'm really tired of this printer, already ordered CR-10S

Re: part cooling issues?

change slicer which puts less material near sloped walls, this helps a lot
print slower to give time for cooling fan to cool down material, turn bed off for PLA because air is heated by bed, then hot air is pulled by the blower
change cooling nozzle but it's not helping much
lower extruder multiplier to extrude less material, because les material cools faster

experiment and check what is working for you
I'm really tired of this printer, already ordered CR-10S

- I have no idea how to make cura add less material near sloped walls, any hints?
- slowing helps a little, but doesn't fix it
- if i turn bed temp below 50C or so, I have adhesion problems
- i am set to 95% extruded material

Re: part cooling issues?

I don know how to fix this issue, honestly I have no clue, that why I just give up with Prusa i3 MK3

- I have no idea how to make cura add less material near sloped walls, any hints?
Cura ..... Don't know but Simplify3d puts less material i managed to achieve good quality prints but not always, so there is no solution 🙁

CR-10S gives more room to improve prints cooling, below is link to my latest project for improving cooling nozzle for MK3 but even with this print quality is far from good

https://www.thingiverse.com/thing:2842948

Re: part cooling issues?

I sent a mail to prusa support...

I wonder wat they will respond...