About the Class

In today's class we learned about the basics of CNC-ing: What materials can be milled in which scenario and with which machines. Multiple examples for 2D and 3D milling were given.

CNC-milling a biomaterial mold

For the homework, George and me decided to mill a 3D mold to manufacture bowls from biomaterial. For this, we prepared a 3D file which was then checked by FabLab staff. Unfortunately the design didn't feature a watertight 3D volume but instead was an open shape. Therefore after perfectly milling our molds, the machine continued to drill into the finished positive and milled it down entirely. The result can be seen below. Let's just say it was a painful, but effective lesson on why to double check your 3D files before generating the g-code.

During the milling process using the Raptor CNC.

The finished piece. In the bottom left, the destroyed positive can be seen clearly.

Further Links

projects
  Standing Desk, Opendesk, AtFab
  Shelter 2.0, yourHOUSE, Wikihouse, FabHouse, Fab Lab House
  10,000 Year Clock
 
machines
  Shaper
  Maslow
  ShopBot
  Onsrud
  Tormach
  Haas
  Hurco
  Zund
  MTM Fellesverkstedet

stock
  cardboard
  rigid foam insulation (gesso, heat gun)
  veneer plywood
  Medium Density Fiberboard (MDF)
  Medium Density Overlay (MDO)
  Oriented Strand Board (OSB), finishing, covering
  Valchromat
  HDPE
  Lexan, polycarbonate
  Garolite
  Aluminum (Composite Panel)

vendors
  McMaster-Carr
  US Plastics
  Admiral Metals
  Home Depot
  Boulter Plywood
  Steritt Lumber
  Beacon Sales

job shops
  Proto Labs
  Star Rapid
  Yubo Precision
  DSH
  Cycle Start
  Fast Forward Composites
  Xometry

tooling
  drills vs mills
  router, V bits
  flutes
  coatings
  center-cutting
  up/down cut
  flat/ball end

speeds and feeds
  chip load: ~ 0.001-0.010"
     feed rate (inches per minute) / (RPM x number of flutes)
  cut depth: ~ tool diameter
  step-over: ~ tool diameter/2

lubricants

abrasive machining, grinding

fixturing
  vises
  bar clamps
  screws
  nails
  vacuum
  wedges
  weights
  glue
  tape
  encapsulation

sacrificial layers, squaring

dust collection

flexures, living hinges, kerfing, steam bending, wacky wood

fasteners, glues

joinery, reciprocal frame, tensegrity, Maxwell criterion

toolpaths
  kerf, offset, runout
  conventional, climb
  rough/finish cuts
  high-speed, dry, ramping, adaptive clearing, swarf, rest, trochoidal
  one-sided, two-sided, registration
  2, 2.5, 3, 4, 3+2, 5 axis
  tool length compensation
  cut depth, clearance, collisions
  T-bones, dog-bones
  tabs, onion skinning
  nesting
  lead-in, -out
  test cuts, cutting air
  simulation
  prototyping

CAM
  CAMotics
  VCarvePro
  FeatureCAM
  Mastercam
  HSMWorks
  CAMWorks
  Freecad Path
  Solidworks CAM
  Fusion 360
  OpenBuilds
  mods community outline rough finish

file formats
  .rml
  .sbp
  .g
  .ord

safety
  training
  splinters, cuts, burns, impacts, fires
  tool breaking
  glasses, shoes, clothes, hair, gloves
  look, listen, smell
  don't reach into a powered tool
  emergency stop, assistance
  personal state

welding
  arc
  MIG (metal inert gas)
  TIG (tungsten inert gas)
  spot
  friction
  ultrasonic

assignment
  group assignment
     do your lab's safety training
     test runout, alignment, fixturing, speeds, feeds, materials, and toolpaths for your machine
  individual assignment
     make (design+mill+assemble) something big (~meter-scale)
     extra credit: don't use fasteners or glue
     extra credit: include curved surfaces