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Although I’ve just recently entered the world of 3D Printing I’ve been doing 3D design for over 10 years – mainly for animation and visual effects projects. My tool of choice for this is Maxon’s excellent
Cinema 4D software. I’m using the latest R15 version and have the Broadcast edition. But the steps below can be done in any edition.
Because I’ve learned that designing objects for 3D printing is different than designing for screen output I decided to do a quick tutorial with some basic tips for optimizing models for 3D printing within C4D.
For this example I’ve made a quick model of a robot by just moving an scaling a sphere primitive and four cilinders. No fancy modeling here I must admit, but let’s pretend I the clock is ticking.
The first thing that becomes important when designing objects for physical output is size. Go to Edit > Project Setting and set the Project Scale to millimeters.
A problem with C4D is that when selecting multiple objects or a group of objects it stops showing the total size.
A workaround for the size indication problem is adding your objects to a Connect Object. As you can see the total size of the object is now displayed. It’s important to set the Phong Mode in the Connect Object to manual. I’ll explain this in the next step.
Phong Shading is used to make objects look smooth on screen. The sphere above looks smooth but it’s in fact made out square polygons as you can see when looking at the edges. To disable this you must select the Phong Tags of all your objects and delete them.
Now you see the actual polygons. A 3D printer doesn’t do shading so your print will look more like this than the perfect smooth image above.
You can add more polygons to you objects by selecting them and increasing the amount of Sements. I changed it from 24 to 96. The value depends on the size you want to print the object at and the print quality of your printer.
If you want to make a small print on a FDM-type 3D Printer that melts plastic filament with an extruder tiny polygons won’t be visible so these settings will be sufficient. But I’ve seen prints from a laser-based Form 1 (stereolitography) printer and those make even tiny polygons visible.
Now you can scale down the object by selecting the Scale tool and dragging somewhere on the screen. Remember that most slicing programs that are used to prepare the model for actual printing will import the model at this size but can also re-scale it. It’s good practice to put the bottom of your print on the floor (Y = 0mm) but if you don’t the slicer software can do this too.
When you’re happy with the size you can hit the letter “O” on your keyboard to zoom in on the object again.
Now we use a little trick inside C4D to take a look inside the object. Go to Edit > Project Settings and scroll down to View Clipping. Depending on what you’re making you can experiment with increasing this setting and zoom in and out of your object to get the desired cross section view. As you can see the Connect Object connects everything but doesn’t delete the parts of the cilinders inside of the sphere. This is no problem for screen output but will cause problems when slicing or 3D printing this object.
If you just have 2 objects that you want to merge into a single object while removing the intersecting polygons, you can put your objects inside Boole Object and set the Boolean Type to A union B. But as you can see that is limited to just the two first objects in the list (the sphere and one of the leg cilinders in this case). Bad Luck… or…?
Luckily there’s a wonderful free plug-in for C4D called Magic Merge. It’s developed by Nitro4D an can be downloaded
Unzip the File, put the new folder in maxon/cinema4d/plugins and quit C4D (don’t forget to save your design!). Re-open C4D and your design.
Now move the objects out of the Connect Objects and delete that. Select all separate objects go to Plugins in the top menu and select Magic Merge.
Voila! A Perfectly Merged objects that’s completely hollow on the inside!
This is a good time disable the cross section view by changing the View Clipping back to something more useful (I prefer Tiny for everything) via Edit > Project Settings.
Now go to File > Export
And select .STL – the standard format used in 3D printing.
Make sure the export Scale is set to 1 if you want the object at the size you designed it.
Now you can send your file to a 3D Printing Service or import it in your favorite Slicing software. I prefer Simplify3D of which I wrote a