Intro: CNC Milled Teapot Sculpture
Teapot is a sculpture that emerged out of inquiry into the simulation in 3d computer software and the effects of transferring an object from the physical world into a virtual world, altering it, and then bringing the object back out, in its altered state, into the physical world.
In this tutorial you will learn how to obtain the 3d geometry, export and mill the object with a 3 axis CNC.
Step 1: Modeling the Form
In order to obtain the draped geometry, I used Maya's ncloth simulation.
You can drape any object you want to make. There are extensive online 3d libraries that offer you plenty of objects to play around with. I recommend you use obj extension or native maya files.
Below are a couple links to some 3d libraries:
The key to obtaining the right geometry for milling is that there can be no undercuts. If you make the settings on the ncloth simulator pretty rigid you will obtain less creases in your geometry, and therefore no undercuts!
Once you have your object picked out, open Maya and go to file>import> open your object.
Create a box for the object to rest on. It will be a sort of virtual plinth for your sculpture: Create>Polygon Primitives>Polygon Cube
You can define the size of your cube in the Attribute Editor.
Now create a flat surface floating right on top of your object. This will become the cloth that gets draped. Create>Polygon Primitives>Polygon Plane
Make sure to add enough subdivisions to this plane in the attribute editor.
Step 2: Creating the Cloth Simulation
First select the cube and the object.
In the FX menu, choose nCloth>Create>Passive Collider
This will make your cloth collide with the object as well as the plinth once it touches it.
Next convert the top surface into a cloth:
In the FX menu, choose nCloth>Create>nCloth
With the surface selected, go to the attribute editor, you will now see that your surface has been converted into an nCloth. I recommend changing the presets of the cloth to a more rigid material in order to avoid undercuts in the final piece. Go to the Attribute editor and in presets, select something like tshirt or thick leather. You should be able to play around with these presets and explore the different outputs of the cloth
In order to preview the simulation, you must allow enough frames in your animation. Setting it to 200 frames should be enough for this exercise.
Now preview the animation by hitting the play button on the bottom of the screen.
Once you obtain the desired shape, select your cloth and hit ctrD. This will duplicate your geometry and make it easier to work with the form without its nCloth properties.
Select your final form that you wish to mill and export it as an STL file.
Step 3: Milling the Form
I used the shopbot CNC mill as well as the Part Works 3D software for creating the toolpaths.
This is a great tutorial that shows you how to get started with Part Works 3d
Make sure you are trained to use a CNC mill. There are several safety measures you will need to know in order to operate the machine.
I decided to slice my 3d model into layers, mill it, and assemble it afterwards. You can also work the other way around. In my case, the machine I used can only mill up to 6 inches deep, which is why I preferred slicing up my model since the beginning.
Step 4: Assemble and Sand
My sculpture was made out of several slices of 3/4 inch plywood.
I first glued the pairs together and clamped them down to allow no air in between layers. Once that was done, I clamped the paired slices together.
My piece required some heavy sanding because of the material that was used to make it. But it was important for the piece to show the layered plywood. I used a Dremel to sand out the finer creases.