Leaving out internal perimeters

Hello everybody,

I am new to 3D printing and have a question about Slic3r for which I could not find an answer.
I have a model with a tube inside it and exported the model itself and the tube seperately.
Is it possible to print the model containing the tube (the outer model) with external perimeters but not internal ones, e.g. on the inside around the tube?
I know it is possible to leave out perimeters entirely, though that is not what is needed.

What I have tried to do is make a little bigger clone of the object for which I need the outer perimeters and hollow it with booleans, however depending on the model the boolean modifiers screw up pretty badly, at least in blender.

I hope the question is somewhat clear

Thanks in advance for your replies!

Edited 1 time(s). Last edit at 06/28/2016 06:16PM by Assax.

You could try using OpenSCAD to modify your STL file with unions, intersections etc to create a single STL model which has the features you need all in one.

Edited 1 time(s). Last edit at 06/28/2016 06:30PM by Mikk36.

Yes, it sounds like the problem needs to be solved by modifying the STL rather than in the slicer. As Mikk36 has said, OpenScad (free) is a good tool to do that. If you upload the STL and exactly what you wish to achieve I am sure that myself or someone else will be able to supply suitable OpenScad code and a brief tutorial that will get you running.

Dave

I don't think you're understanding. The OP wants to omit the perimeters on the periphery of the hole in the part so the infill goes all the way to the edge of the hole without omitting the exterior perimeters. Slic3r doesn't have that functionality. I can think of a couple off workarounds...

1) Take the outer surface of the part and thicken it by the number of perimeters you want times the perimeter extrusion width. Set this part as a modifier with half the desired number of perimeters and set the main part with zero perimeters.

2) Build the hole undersized by the number of perimeters times the perimeter extrusion width, then go into the gcode and delete the lines for printing the perimeters around the hole.

Hello everyone,

Thank you for taking your time to reply and for your suggestions.
I think IMBoring25 has understood me correctly. As an example of what I strive to achieve I will upload an image.



The center will be filled with other filament which I left out of this image.

Basically what I am trying to do is keep the walls of the cube but not the walls / perimeters surrounded by the blue circle.
For basic objects like a cube it is somewhat easy to do by just making a slightly bigger cube and making it hollow inside, print that one with solid perimeters and the inner cube without perimeters, for some more complex objects sadly it is not that easy.

Quote
IMBoring25
2) Build the hole undersized by the number of perimeters times the perimeter extrusion width, then go into the gcode and delete the lines for printing the perimeters around the hole.

I was already thinking of this but did not get to try it yet. I will see if I can find the lines that print the "internal" perimeters.
I am not sure I understand 1) correctly though. I think it is going in the same direction as I have tried to do in blender though where I duplicated the object solidified it with a higher thickness and then used the original one to hollow out the duplicate and then use that hollow duplicate as perimeter.
Unfortunately the boolean modifiers are not working as I wished they would because there are always some parts that overlap in the models that should not overlap etc.

Edited 5 time(s). Last edit at 06/29/2016 12:54PM by Assax.

Surely the edges of infill that are not supported by a perimeter are going to be ragged and weak?

Dave

That is exactly what I need. I am printing with exotic materials and the perimeter inside is causing me issues because it isolates too much.
Just having rectiliniar infill attached to the cylinder in the center is what I need but I still need the perimeters on the outside of the model.

All I can suggest would be to construct the infill pattern in the STL and print without infill. I have seen models where that has been done in order to provide optimum strength, e.g. the demo wing section attached.

Dave