Eliminate surfaces between models/colors

[kfsone 5]

I have a model which is a 3mm thick square with raised letters above it. The idea was to print it using dual extrusion, so I made it two models, assigned each to an extruder, and grouped them. But when I look at the preview, it's burning a whole lot of time creating skins at the interface. How can I stop it doing this? (Pardon the colors, I gave up fighting cura on choosing what color non-ultimaker filaments are)

 

 

[geert_2 558]

If the model is opaque, and the letters are raised, then maybe you could make the whole baseplate in one solid model/color? And only switch to the letters once you are above the baseplate? Thus without digging into the baseplate, rather like icing on top of a cake?

 

If it has to be transparent, or if the letters are recessed into the baseplate, then of course this method would not work.

 

(Note: I don't have dual-nozzle printers, so no experience, and just guessing.)

 

[kfsone 5]

Even with the letters above the baseplate it generates surfaces between the two, that was what lead me to try recessing them. Hmm. Maybe I should recess them but not cut the recesses out of the baseplate.

 

[kfsone 5]

That didn't fix it, but it did affect alternate mesh removal's impact:

 

 

But it still produces two surfaces where the letters meet:

 

 

Edited February 11, 2020 by kfsone

[kfsone 5]

Turning off Remove Mesh Intersection entirely seems(*) to have fixed it (although, that seems backwards)

(It created a different problem: it tries to print layers for both models at the same time instead)

 

Edited February 11, 2020 by kfsone

[kfsone 5]

Here's a trimmed down version of the two models.

X-Base.stl X-Fore.stl

[geert_2 558]

15 hours ago, kfsone said:

Here's a trimmed down version of the two models.

X-Base.stl 684 B · 0 downloads X-Fore.stl 127.52 kB · 0 downloads

 

This is indeed what I would expect to work, at least if you have 100% infill. If less than 100% infill, say 20%, then I could imagine that the slicer would generate a heavier structure below the letters, to support them.

 

I guess this will have to be answered by the developers, or people with a dual-nozzle machine and a better understanding of the slicing-internals.

 

[tinkergnome 927]

On 2/11/2020 at 8:47 AM, kfsone said:

But when I look at the preview, it's burning a whole lot of time creating skins at the interface.

 

I guess you can't prevent this entirely.

The base plate and the letters are two separate models after all and cura will always print them as such.

 

Probably more important: both models should not overlap in the first place.

The base should have appropriate pockets in places where the letters are located later. This would eliminate the need for "Remove Mesh Intersections" by the slicing software (as well as any other subsequent "tricks" and "mesh fixes").

 

I think the intended Cura function to align dual color models is called "merge origins", not "group".

 

I'm not sure: is it possible to change the wall line count and/or bottom height in the "per model settings"?

So that you can set both to zero, but only for the letters?

 

[kfsone 5]

@tinkergnome see my response a couple replies above, which has an example model pair. I tried messing with the per-model settings but there was nothing I found that produce settings equivalent to simply switching nozzles while rendering the parts of a the letters. I should note that unlike the simple X model, there's actually some other stuff on my original (a border, etc) that would preclude my simply changing nozzles at layer N 😞

Where do I find the "Merge Origins" option???

Lastly, I tried making the models not actually overlap and separated them by .1, .5, 1.0 and 1.1x layer height, all to no avail.

I've carefully made as many of the non-material settings the same across the two nozzles as I could, but no effect.

 

[kfsone 5]

19 hours ago, geert_2 said:

 

This is indeed what I would expect to work, at least if you have 100% infill. If less than 100% infill, say 20%, then I could imagine that the slicer would generate a heavier structure below the letters, to support them.

 

I guess this will have to be answered by the developers, or people with a dual-nozzle machine and a better understanding of the slicing-internals.

 

I tried to match as many settings between extruders as I could (I have to tell you *that* is tedious, it takes so long to switch between setting lists, if dual extrusion becomes popular, people are going to flee cura faster than you can say "do you think this extruder's settings will load any time this week?")

In some of the previews it looked like the infill was aligned, but that could be coincidental 😞

[geert_2 558]

11 hours ago, kfsone said:

...
Lastly, I tried making the models not actually overlap and separated them by .1, .5, 1.0 and 1.1x layer height, all to no avail.
...

 

 

I was about to suggest this. 🙂

 

If they are totally separate, with a gap, and support is switched off, I see no reason at all why the base plate would be influenced by the X-character? Weird...

 

1. Have you tried printing them in one material, with only one nozzle? But with tiny gaps everywhere (even 0.01mm should do)? Just to see how it is sliced?

 

2. Have you tried putting both models into one STL-file? (Your models above are in separate files.)

 

At 100% infill, on my single-nozzle UM2, the model below is sliced correctly in my older Cura. I quickly created it in DesignSpark Mechanical, and exported it as one STL-file. There is a tiny gap of 0.1mm between X and base. Base is 20mm x 20mm x 2mm. At less-than-100% infill, the area below the X is hollowed out according to the fill-percentage, but without outlines.

 

 

STL-file: x_on_base1.stl

 

Edited February 13, 2020 by geert_2

[tinkergnome 927]

6 hours ago, kfsone said:

Where do I find the "Merge Origins" option???

 

sorry, it's called "Merge Models" in Cura...

 

https://ultimaker.com/en/resources/52852-merge-and-group-models

 

 

 

 

 

41 minutes ago, geert_2 said:

If they are totally separate, with a gap, and support is switched off, I see no reason at all why the base plate would be influenced by the X-character? Weird...

 

I may be wrong, but i think @kfsone wants to achieve the opposite.

He expects that both parts are printed only with infill (without top and bottom layers) in areas where they "touch" each other. Like: handle both models in the same way as a (merged) single shell, but use a different color (extruder) for the details.

 

I'm not aware of any slicer that behaves this way. 🤷‍♂️