CNC milling

Owned by Tod Zhu
Last updated: May 16, 2022
3 min read


Considerations for this method

In addition to file prep, fabrication, and assembly time, CNC milling requires:

  • Material preparation time
    • Plywood: cut down, glued, clamped, left to dry
    • Hardwood: planed, cut down, glued, clamped, left to dry
  • File review and approval wait time
  • CNC appointment scheduling

If you're unfamiliar with Mastercam, your first CNC milled model will take much more time to prepare than an equivalent laser cut model. Once you become familiar with Mastercam and the milling process, it becomes much less time intensive.

PROS:

  • Large, seamless models are possible
  • High degree of precision

CONS:

  • Steep learning curve
Limitations for milling context buildings
  • In foam, buildings can be about 2" tall. Tall buildings must be at least 1/4" apart. Shorter buildings (<1") can be 1/8" apart.
  • In wood, buildings can be about 1" tall.


On this page

Material choices


METHODMATERIALCOST ($/sf)

TIME:

file prep

TIME:

fab

TIME:

assembly

TIME:

total

MATERIAL
RECYCLABILITY
CNC milling - smooth terrainwhite foam$8720.259.25yes (special service provider)
CNC milling - smooth terrainplywood$409.5
 6.75

2.25 h to mill the base,
4.5 h to cut the buildings

117.25yes (if unpainted)
CNC milling - smooth terrainhardwood (poplar)$349.5
 6.75

2.25 h to mill the base,
4.5 h to cut the buildings

117.25yes (if unpainted)

CNC milling - smooth terrainhigh density foam$837

2

0.259.25no
CNC milling - stepped terrain (fine)white foam$8143.60.2517.85yes (special service provider)

CNC milling - stepped terrain (1/16" contours)white foam$8720.259.25yes (special service provider)

File preparation: Rhino

  1. Generally, the rhino file prepared for milling must contain the following layers:
  2. Stock: a box, at the world origin, representing the size of the block of your milling material.
  3. Topography: a single NURBS surface for smooth terrain, or a series of flat surfaces for stepped terrain.
  4. Features: layer(s) with NURBS surfaces for roads, water, etc.
  5. For each features layer, there should be another layer with boundary curves for each feature surface.
  6. Buildings: If buildings are to be milled with the base, include a layer with NURBS surfaces at the tops of buildings.
  7. A layer with boundary curves for each building top surface.
  8. Buildings too large or too small to be milled with the topography need pockets. Include a layer with curves outlining the bases of these buildings (at the z depth you want the bottom of the pocket cut).
  9. Final contour: a layer with a curve tracing the four outside edges of the topography layer, and the same curve projected to z=0.
  10. This file can be imported directly into Mastercam.

File preparation: Mastercam

  1. See the CNC tutorial for more detail. In general, you will need to use a template MasterCAM file, import your geometry, assign it to pre-defined toolpaths and adjust the toolpath parameters for your material.
  2. Files must be submitted to CNC TAs for review and approval.


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