Multiple Density Slicing in Cura

[plokij0802 0]

Hello world!

 

I am currently working on a work project and need your help!

I work in a cancer treatment facility and we would like to try printing a 3d scaned (as in medical scanner) body part.

All the organs are contoured and we have an STL file out of it.

What we would want to do is print different densities corresponding to different organs. The first idea is to make a puzzle and assemble the various parts, but I feel like having a one part print would be so much more user friendly...

please help!

for obvious reasons, I can't send you the patient's scan but we are also working on a model from a lab rat that I can share.

 

H

[P3D 46]

What exactly do you mean by "densities"? Infill percentage? Layer height? Maybe even a different material?

[plokij0802 0]

actually both... Different filament might come in later but not quite yet, baby steps might take me all the way there!

 

[Dim3nsioneer 557]

This is what you could do with Cura.

First, split into subsets of the parts with the same density. Their origin and scal should of course be the same.

Then load the different subsets into Cura. Use the per object settings on the left and select "infill density". Select each subset and assign an infill density to it. Finally, select all subsets, right click on the selection and use the "merge models" function.

You can also assign one or more subsets to the second extruder if you want to print it with a different material/color.

[plokij0802 0]

a bit of a noob here I'm afraid, you meen in the 3d modeling software or in cura?

thanks!

 

H

[Dim3nsioneer 557]

You have to create the subsets in the 3d modeling software or whatever software you use. If you don't have any software you can use for this, you might want to check out Autodesk Meshmixer.

[geert_2 557]

Wouldn't the easiest thing be to split each organ or body-part into a different file? And then print each file *separately* with the desired settings that show it best (color, layer height, speed, infill percentage, temperature...)? All of course in the same scale, like Dim3nsioneer said.

 

For example, then you could easily print the heart-file in rose, liver-file in brown, lung-file in pale rose, brains in cream, bones in ivory color, etc...

 

I don't know in how far your medical software allows such splitting off of parts?

 

[plokij0802 0]

11 minutes ago, geert_2 said:

Wouldn't the easiest thing be to split each organ or body-part into a different file? And then print each file *separately* with the desired settings that show it best (color, layer height, speed, infill percentage, temperature...)? All of course in the same scale, like Dim3nsioneer said.

 

For example, then you could easily print the heart-file in rose, liver-file in brown, lung-file in pale rose, brains in cream, bones in ivory color, etc...

 

I don't know in how far your medical software allows such splitting off of parts?

 

 

We are also looking at that alternative, but the one part print is a more reel body and not a split open.

We want to scan a skull and not have to inconvenience of having a line where the cut would have to be.

 

25 minutes ago, Dim3nsioneer said:

You have to create the subsets in the 3d modeling software or whatever software you use. If you don't have any software you can use for this, you might want to check out Autodesk Meshmixer.

 

I use Fusion 360 but I'm not an expert on that one either, it might take time but I'll get there!

Thanks for the great advice!

 

H

[P3D 46]

What I still don't get is how the different infill densities will help you in the final print, because most probably you won't be able to tell the difference between the parts, as the surface is composed of wall layers anyway... or is it a section view, and you will print without top layers? Then it makes sense of course. 

 

By the way, as far as I know you can't print different parts with different layer heights in one go. You can alter infill pattern and infill density, though. For this, you have to have the part as different STLs, but with the proper coordinates, so you can pick "per object" settings in Cura and then merge the objects together, as you would do with a multi material print. 

Edited October 3, 2018 by P3D

[plokij0802 0]

12 minutes ago, P3D said:

What I still don't get is how the different infill densities will help you in the final print, because most probably won't be able to tell the difference between the parts, as the surface is composed of wall layers anyway... or is it a section view, and you will print without top layers? Then it makes sense of course. 

 

By the way, as far as I know you can't print different parts with different layer heights in one go. You can alter infill pattern and infill density, though. For this, you have to have the part as different STLs, but with the proper coordinates, so you can pick "per object" settings in Cura and then merge the objects together, as you would do with a multi material print. 

 

I have told them about that kind of issue, that a slice of a 3d print even with a different infill density will only show the infill patern used in each part of the print. The physicists and physicians don't seem to either understand (wich they would never admit) or don't care enough - both are possible.

 

I'm seeing it as I next level challenge and it would help me personally in learning more about 3d printing and slicing. As I know we can set with the "per model setting" different almost everything, and using a double extruder we can use multiple types of material, I just thought a combo of both would be 1. possible and 2. the next step up...

 

Thanks to all of you guys!

 

H

[P3D 46]

To make my point clear: What I mean is that you can select different infills allright, as seen in the partial layer view:

But you can't see this in the finished object, as the bottom, walls and top are all solid:

[geert_2 557]

I have a bit the feeling that the physicians want it to be like a röntgen: high-density material for bones, medium density for the rubbery stuff in joints (="kraakbeen" in Dutch, but don't know the English term), low density for flesh, and ultralow density for liquids. Is this correct?

 

But that is not how an FDM 3D-print works. At least not with traditional slicers. It just prints a *solid* outer shell, filled with a rectangular grid (usually) to add strength, so the walls don't collapse. Maybe the physicians don't understand this concept, and they are stuck with the grayscale röntgens (or MRI, echo, or whatever scans) in mind? If so, simply print a test model, stop the print halfway so that the grid is visible, and use that as a demo?

 

If this gradual soft to hard approach - or something equivalent - is what they really want, maybe it could be achieved with "inkjet-style" 3D-printers? These spray a liquid, which is then cured by an UV-lamp. The more expensive machines (100.000 euro or more) can mix different liquids in different ratios. So they could mix a flexible liquid and hard liquid (= hard after curing) in ratios from 0 to 100%. Thus by mixing it in various quantities, you could go from very soft to very hard materials in one single model. Of from opaque to transparent. Or from one color to another in fine gradients. But this is not something you can achieve with an FDM 3D-printer.

 

If you have a dual-nozzle printer, and you don't need support material, you could use one nozzle for hard material (or for one color), and the other for somewhat softer material (or for another color). But this is still a sort of "digital" on/off solution, not on a gradient.

 

I am just guessing here, but if this is correct, maybe you first need to clarify the confusion and to educate the other people involved?