Tutorial Intermediate ⏱ 15 minutes

Flange Profile

Create a complete circular flange with central bore, bolt-hole pattern, and outer diameter — a standard engineering component.

What You Will Build

A 120mm OD flange with 40mm central bore, 6 bolt holes (M8) on 80mm PCD, and 5mm thickness. Complete 2D geometry for CNC 3-axis milling operations.

Operators Used

Circle/Centre,R Points/On,C,N Line/Parlel,XAxis,D

Define the Flange Geometry

Plan all dimensions before starting construction.

Flange dimensions:
  Outer diameter (OD): 120mm  → radius 60mm
  Central bore:        40mm   → radius 20mm
  Bolt hole PCD:       80mm   → radius 40mm
  Bolt hole diameter:  8.5mm  → radius 4.25mm (M8 clearance)
  Number of bolt holes: 6
  Thickness: 5mm (Z-depth in CAM)

Create the Outer Diameter

Create the outer circle of the flange.

P_centre = (0, 0)  [flange centre]

Circle/Centre, P_centre, R=60, 0
→ C0: outer diameter, centre=(0,0), radius=60mm
   OD = 120mm

Create the Central Bore

Create the central bore circle.

Circle/Centre, P_centre, R=20, 0
→ C1: central bore, centre=(0,0), radius=20mm
   Bore diameter = 40mm

Both circles are concentric at the origin.

Create the Pitch Circle

Create the pitch circle for the bolt holes.

Circle/Centre, P_centre, R=40, 0
→ C2: pitch circle, centre=(0,0), radius=40mm
   PCD = 80mm

This is a reference circle — it defines where the bolt hole centres will be placed.

Create Six Bolt Hole Centres

Place 6 equally spaced points on the pitch circle.

Points/On, C2, N=6, Angle=0, 0
→ P0 = (40, 0)         [at 0°]
→ P1 = (20, 34.641)    [at 60°]
→ P2 = (-20, 34.641)   [at 120°]
→ P3 = (-40, 0)        [at 180°]
→ P4 = (-20, -34.641)  [at 240°]
→ P5 = (20, -34.641)   [at 300°]

Create the Six Bolt Holes

Create M8 clearance holes at each bolt hole centre.

Circle/Centre, P0, R=4.25, 0  → C3
Circle/Centre, P1, R=4.25, 0  → C4
Circle/Centre, P2, R=4.25, 0  → C5
Circle/Centre, P3, R=4.25, 0  → C6
Circle/Centre, P4, R=4.25, 0  → C7
Circle/Centre, P5, R=4.25, 0  → C8

All holes: diameter = 8.5mm (M8 clearance)

Clean Up and Verify

Delete construction geometry and verify all dimensions.

Edit → Clear All Points
→ P0-P5 deleted, C0-C8 unchanged

Optional: Undo C2 (pitch circle) if not needed in final drawing

Verification:
  OD = 120mm ✓  (C0 radius = 60mm)
  Bore = 40mm ✓  (C1 radius = 20mm)
  PCD = 80mm ✓  (C2 radius = 40mm)
  Bolt holes: 6 × 8.5mm diameter ✓
  Hole spacing = 2×40×sin(30°) = 40mm ✓

The flange geometry is complete. Set up CAM with: OD profile milling (C0), bore milling (C1), bolt hole drilling (C3-C8). All operations are 2D 3-axis milling.

Tips & Best Practices

Always verify PCD and hole spacing with Measure → Distance before CAM setup.
For metric flanges, use standard PCD values from engineering tables.
The pitch circle (C2) can be kept as a reference or deleted after placing holes.
For a counterbored flange, create a second larger circle at each hole centre.
Use the Toolpath Simulator to verify drilling sequences before machining.