How to print bumps

[philippxmeyer 1]

Hi everybody,

 

i'm a mechanical engineer but quite new to 3d printing, please forgive me, if my question is answered a million times before, in that case just help me with some links and keywords 🙂

 

I ran into this problem with a part i don't really know what it was, nevertheless i just drew an example in solidworks:

 

When i slice this in Cura, it makes the layers below the Bumps look like this:

 

Problem is, Cura prints the outlines to the holes in the infill in mid-air, causing some fuzz and imperfections:

 

Is there any possibility to just print the surface as a whole and the bumps on top of that?

That would save lots of printing time and the outcome should be much better.

Or am i running in some noob problem and the answer is simply: "It's okay the way it is"?

 

Kind regards

Philipp

[DivingDuck 105]

Without seeing your project file it is quite difficult to help.

In general, your infill pattern do not meet your model. Especially when you look to the shown infill density. You either need to find a better matching pattern  and / or change the density.

Take also a look for infill support, gradual infill steps and adaptive layers.

I had for the lather one in the past often problems with accuracy in z height/dimensions for my models, so this is something you need to inspect when choosing.

 

Edit:

 

I just play a bit with this kind of model, maybe this is interesting for you:

 

Activate Infill support and add some extra meet for supporting the sphere holes with skin edge support layers (e.g. 3...5 additional layers). Also it makes sense to have more than one wall...

 

 

An other trick/way is  to solve this problem is by design. Separate all halve sphere's and move them a little bit up so that there is a non printable gap, let's say by 0.01 mm. Cura then will think, these are individual bodies and print a closed top surface before printing all halve sphere bodies. This is also a way to generate a nice unbroken top surfaces.

 

Edited February 26, 2022 by DivingDuck
some more help

[ahoeben 2,012]

See the "Skin Removal Width" setting: https://github.com/Ghostkeeper/SettingsGuide/blob/master/resources/articles/top_bottom/skin_preshrink.md

[philippxmeyer 1]

3 hours ago, ahoeben said:

See the "Skin Removal Width" setting: https://github.com/Ghostkeeper/SettingsGuide/blob/master/resources/articles/top_bottom/skin_preshrink.md

Almost perfect, thank you.

It was not the "Skin Removal Width" but the "Skin Expand With" that needed to be increased.

Now it generates a flat surface and the bumps printed on top of it 👍

 

It also came back to me what the original problem was, it was a rooftop for my father's model railway.

With the different setting the print time is reduced from 5 hours something to 4 hours straight.

 

 

Best regards

Philipp

Edited February 26, 2022 by philippxmeyer