Printing Surfaces or Hollowing Out a Solid
Hey all,
I am looking for a workflow for printing an RC Car Body Shell. For the uninitiated, these are normally made of .2mm to .4mm lexan sheet vacuum formed over a positive. They are thin and light.
I would like to use my 3D printer to print one, instead. I have tried two work flows.
1. Printing a surface. Because the surface is of a non-unit thickness, the slicer has a hard time figuring out what to do.
2. Printing a solid but removing the bottom. This would work IF I could replace the infill with support material.
Number 2 sounds like the most immediate solution. How can I replace the infill with support material?
Number 1 would be ideal. How could I thicken the surface such that the outside is respected dimensionally and the inside could be grown.
It seems to me that the slicer is the best tool for this because it would just have to assume a minimum thickness and I could simply tune it to go in or out based on face normals or some such.
Ideas?
RE: Printing Surfaces or Hollowing Out a Solid
Adding this picture for surface workflow
RE: Printing Surfaces or Hollowing Out a Solid
Example of Lexan Body on RC Car (unpainted)
While being painted
Fully Painted
RE: Printing Surfaces or Hollowing Out a Solid
Your problem is the model. For a slicer to function it HAS to be manifold. It must be a 'watertight' 3d solid shape, it cant just be a surface. You basically need to add thickness to your shell which is a function of CAD software and should not be tried with a slicers 'best guess'. You might assume that it can 'just add thickness' but it cant. Slicers just don't work that way. Even printing vase mode requires a solid starting shape.
Depending on what CAD software you use adding thickness can be trivial to frustrating. It depends on the original model geometry and type.
Zip up and attach a model or 2 and I'll take a look and see how easy it is. Must be zipped for the forum to accept the file types.
RE: Printing Surfaces or Hollowing Out a Solid
As a data point, I think the magic term you are looking for is EXTRUDE. Most CAD tools have the ability to extrude surfaces.
Using Slicer, (guessing a bit here based on multi color printing) you can probably set up the multi-extruder mode, and set one of the extruders to use soluble material. It would get you to the point of printing a solid body using two materials.
By the looks of the vertical tail section - the model is a solid. So tools to make the shell hollow may help, too.
As Neo suggested, zip the model in question (.stl) and post it here.
RE: Printing Surfaces or Hollowing Out a Solid
@neophyl
Yes, I gettit. I have been using 3D printers since 2006. I designed 3D printers with Type-A machines.
But what is a manifold? It's a volume enclosed by a surface.
Slicers have no trouble finding where the surface intersects with a slice.
I am merely suggesting that this could be a method for making 3D printable non-manifold surfaces.
This is an arbitrary limitation that prevents a wide number of applications.
RE: Printing Surfaces or Hollowing Out a Solid
@tim-2
You can extrude a face. You cannot extrude a surface. Extruding EVERY FACE of a surface is called "thicken" and this is what it looks like
Before
After
RE: Printing Surfaces or Hollowing Out a Solid
@coreyfro
If you want the Slicer to have a new feature then you need to open an issue on the Prusa Slicer github page. https://github.com/prusa3d/PrusaSlicer/issues
Also could you please supply the requested 3mf or model so that we can at least try different option that may or may not help.
RE: Printing Surfaces or Hollowing Out a Solid
@coreyfro
Perhaps I am confused. It seems you know more about the problems and solutions than the people you are asking for help from. You even showed one of the solutions you were asking for. And your point regarding the difference between a surface and a face is earth shattering, and how you can't extrude a surface is ... well something I never knew. And you should let Solidworks know they are doing the impossible:
Extruding Surfaces from a 2D or 3D Face
- Click Insert > Surface > Extrude.
- Select a face: ...
- Select other faces to define the extrude as required. ...
- Select the end condition.
- For 3D faces, select a plane, edge, 2D face, or sketch line to define the direction of extrusion .
http://help.solidworks.com/2020/english/SolidWorks/sldworks/c_Surface_Extrudes.htm
RE: Printing Surfaces or Hollowing Out a Solid
Bug/Feature generated
RE: Printing Surfaces or Hollowing Out a Solid
@coreyfro
Thanks for contributing!
Each entry adds to the software and generates new ideas.
--------------------
Chuck H
3D Printer Review Blog
RE: Printing Surfaces or Hollowing Out a Solid
@coreyfro I have been printing r/c helis, so I understand the issue. As others have said, workflow 1 is done in CAD, and may not trivial. I work in Fusion 360 and find that it can often refuse to thicken complex surfaces.
Workflow 2 does work in the slicer. My workflow is to split parts into smaller ones (as you have done), and then set the number of perimeters to 2 (I find PS can add weird infill material with one perimeter set, even when 'ensure vertical shell thickness' is not checked - this looks like a possible bug). I have then used the grid style infill at a low value (5-10%) to allow it to support the printing of the shell. You can use modifiers to vary the infill density and/or location to suit, as you may not want it everywhere. This won't separate like support material, but you can set the anchor to be a minimum amount.