RSS/Atom3D Printing Textures
She’s right, it is a cool rocket. Lets make our own version.
Ignoring the bit at the top, the rocket shape is quite simple and easy for us to model in CAD. There is also a cool chaotic knurled texture and that’s what this post focusses on.
Step 1 - Precise model in Fusion 360
If your good with blender, you could very easily model this whole item in there, but I’m more interested in building my CAD skills so we will use Fusion 360 to design the rocket and also make the fins separate and attach with a simple push together pin and socket fixture.
The rough steps to model the rocket were:
- Draw the rocket profile as a sketch and revolve it
- Model the fin profile and extrude it
- On the bottom of the fin, add a circular feature and sweep it with a negative taper, using the fin itself as the sweep path
- At the top of the fin, sketch 2x pins and extrude them, add fillets for strength
- Duplicate the fin and use the pull-push tool to make all body-contact surfaces larger, use a
tollerancevariable for this.0.4worked nicely for me. Move the fin about 1-2mm closer to the body so there won’t be a gap mating a flat surface to a curved one - Circular pattern the “real” and “tool” fins around the axis
- Combine the “tool” fins into the body as a
cut - Fillet, chamfer, etc
- Export STL and test print
Step 2 - Add texture in blender
Now we get to the fun part: Adding a texture. You can do this in fusion 360 but it’s more geared around repeating simple shapes and starts going very slow when you add a lot of objects. Blender eats this kind of job for breakfast and lets you use much nicer textures that have a more worn or organic appearance by using graphics files as height maps.
Since we want textures to show up on a 3D print, we need to modify the actual vertices of our object, not just change the way it renders, so shaders are out. The term for this is displacement
There’s some really good tutorials on how to do this, I followed this one and built this object
Important concerns for texturing in blender, once familiar with the basics:
1: displacement works by moving vertices, so if you don’t have enough of them, your object will look terrible. You can use subdivide in edit mode from inside blender but a much better option if you own the CAD file is to just export a mesh with more vertices in the first place. I got good results by setting Maximum Edge Length to .3 which was the smallest value it would accept
2: On non-basic shapes, you need to use UV mapping to apply the texture properly, or you will see incorrect projections as below (note local Coordinates setting):
UV just means a separate coordinate system for texturing, just like you have XYZ for 3D space.
To fix this bad texturing, hit tab to enter edit mode, then find Smart UV Project in the UV top menu bar (not to be confused with the UV Editing in the adjacent view modes):
You will then be able to select a texture and control where it appears on the skin of the unwrapped object. If you care about visible seams, etc you can fix that here. I just used it to control the scale of the texture.
Back in object mode, make sure Coordinates are set to the UV map you just created and the texture will be shown correctly:
3: Parts that need to be dimensionally accurate such as our press-fit pins and sockets must not have any texture or parts won’t fit properly. You can control this 100% in blender by selecting the mesh elements that should be textured and unwrapping just those. To get the cleanest possible selections however, I found it was easiest to just split the parts in Fusion 360 into texture vs no texture. I could then import the split-up parts into blender and just use a in edit mode to select object-by-object where textures should be applied. This way I was able to leave the pins and sockets clean. Other approaches like exporting my original cutting tools from Fusion and trying to use boolean modifiers to recut clean shapes did not work as the displace moves edges to such an extent that they no longer intersect.
4: To create STLs for printing in Blender, just use the File -> Export to create STLs. You can choose to output only selected objects here to reassemble the split up objects, however, this can result in hidden internal textures, like this:
This will increase print time and materials somewhat, although in does seem to print with no issues. To prevent this, combine objects that should be a single physical object in Blender before exporting.
The Result
Textured parts
Fully assembled
Download on printables.com
You can print your own if you like
Why not just get AI to make it?
Felt like up-skilling on this simple object for fun. Learning these basic techniques also helps ground my own understanding so I can prompt more accurately and use less tokens. I got a lot of help with researching techniques with AI chat though.
bumpmesh.com - specialist tool
After completing my design, I stumbled on https://bumpmesh.com by CNC Kitchen.
If you haven’t seen CNC Kitchen’s videos on youtube about 3D printing you should look him up. He goes into great detail on things like part strength as well as introducing heat set inserts to the community.
This solves most of the problems above with a simple web interface. Next time I don’t feel like firing up Blender I’ll give it a go. Video here.
Verdict
Adding surface textures in Blender looks outstanding and hides many surface defects that would otherwise be visible. Altering objects at the mesh level with Blender or other tools is THE way to do for repeatable and easy printing.
Have fun!