Curved shapes top layer
Hi, just wondering if anyone could help with this. Anytime I print a cylinder/curved shape the last layer is always poorly print. Even when slicing on Prusa Slic3r the render shows that there will be gaps with thick lines and the print out result is not much difficult from what the slicer shows.
If it a square or rectangle shape it's fine. This only happens with curved shapes.
I am guessing this is related to the layer height needing to be variable? Or perimeters?
I am using the default profile settings and the problem can be slightly improved if printing at 0.1 quality instead of 0.3 draft mode.
Is it possible to print smooth cylinder shapes? I have tried orientating the print to avoid supports and in theory it should print fine but always have a mess with the last layer.
Thanks.
RE: Curved shapes top layer
It is almost impossible to get the rounded surface nice, and it depends on the large overhang. Support can make it better, but it would be best to take advantage of the 45-degree rule.
My suggestion is that you redesign your detail according to my picture. The right one is good, but the left one is best.
Bear MK3 with Bondtech extruder
RE: Curved shapes top layer
Thanks for the suggestion.
The problem is, it has little to do with the supports. It's more to do with the slicing. It is much better in Cura, the exact same STL file in the same orientation it will print out much smoother.
It's as if the perimeter of layer height is an issue.
See below image of the slicer preview. The red zone in the middle of the cylinders appears regardless of support or orientation.
I will try your suggestion too and see how it slices.
RE: Curved shapes top layer
The red sections is also affected by extrusion width.
A 0.4 wide string cant only stagger so much for each layer to make a rounded shape while laying flat.
To compare, try standing them up in slicer and you will get very nice cylinder, but with the square plate now in mid air which would need support.
Prusa Mini+ kit. BondTech extruder. FW 5.1.2
Prusa MK3S+ kit. Stock. FW 3.11.0
Prusa MK3S+, used. Stock. FW 3.13.3
RE: Curved shapes top layer
Yes, standing them upright makes a big difference. However, for example, if you have a proper cylinder tube with a round cap at the end, it will need support in the entire vertical tube to be able to print the cap at the top.
I suppose this is the compromise then to be had.
Any specific extruder width or perimeter settings people use when printing rounded objects?
Is it even possible to print a spherical ball like a golf ball or is it impossible then given the extruder width issue? Just curious.
RE: Curved shapes top layer
I will add some pictures of the slicing with the cylinder standing vertically so anyone else struggling can see the difference it makes.
I've also attached a picture of a sphere and wondering if anyone has tips on how to get the top of the sphere smoothed out? Those red lines, would they respond to any variable height settings?
RE: Curved shapes top layer
As for the sphere, it's almost impossible to get good bottom curve due to how overhangs work. I guess a wide nozzle, and low layers might (in my head atleast) as you have more of the previous layerwidth beneth.
And sometime, it might just be a better design choice to glue the cap and print them flat separately.
If the distance is not to far, bridging might work as well. A short testprint of the cylinder with cap is one way to check that option.
I usually add another top layer, if i have course infill or odd shape below the surface.
For the square, something like this might work to avoid supports (you get 45deg angles and short bridges between, based on your slicer screenshot of parts).
Prusa Mini+ kit. BondTech extruder. FW 5.1.2
Prusa MK3S+ kit. Stock. FW 3.11.0
Prusa MK3S+, used. Stock. FW 3.13.3
RE: Curved shapes top layer
Found my old flashlight holder, similar design.
Printed upright, the holes are for screws so i just drive thru them.
Prusa Mini+ kit. BondTech extruder. FW 5.1.2
Prusa MK3S+ kit. Stock. FW 3.11.0
Prusa MK3S+, used. Stock. FW 3.13.3
RE: Curved shapes top layer
Interesting, thanks for the examples.
RE: Curved shapes top layer
@mk3s19
These pictures show the top of a 36mm sphere (the bottom was morphed into a shaft to make a knob handle... )
I used the variable layer height option to improve the finish,
with an FDM printer you are always going to get some layering!
An MSLA printer like the SL1 would do a better job. because it can use much finer layers
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Curved shapes top layer
Another way could be to have built-in breakaway supports.
Similar to this print: https://www.prusaprinters.org/prints/28010
Prints upside-down, with thin strip of support that breaks away when finished.
More design-intensive and not suitable for all designs, but allows for more direct (or easy) control over how and where supports are placed or needed.
Prusa Mini+ kit. BondTech extruder. FW 5.1.2
Prusa MK3S+ kit. Stock. FW 3.11.0
Prusa MK3S+, used. Stock. FW 3.13.3
RE: Curved shapes top layer
I have another print to share for some feedback/advice - it is a hollow tee piece.
Original (note the red bits):
When rotated 90 degrees at Y axis, much improved but still there is a red area which results in poor prints with stringing:
Using variable layer height tool, this can be further refined into:
Not bad right?