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Usage Guide

Quick Start Guide

Step 1: Prepare Your Model

  1. Open your model in FreeCAD (or create/import one)
  2. Ensure the object is a solid (not a shell or surface)
  3. Select the object in the 3D view or tree view

Tip

If you imported an STL, it should already be a valid solid. If you created the model in FreeCAD, make sure you created a solid object in the Part workbench.

Step 2: Launch the Macro

  • From Macro Menu: Macro → Macros... → Select "CutObjectForMagnets" → Execute
  • From Toolbar: Click the macro icon (if you created a toolbar button)

Step 3: Configure Cut Plane

The dialog will open with several configuration sections.

Option 1: Preset Plane (Simple, axis-aligned cuts)

  • Plane: Choose orientation
  • XY - Horizontal cut (most common)
  • XZ - Vertical cut (front-to-back)

  • YZ - Vertical cut (left-to-right)

  • Offset: Position of the cut plane from origin (in mm)

  • 0 - Cut through the origin
  • Positive values move the plane in the positive axis direction
  • Negative values move it in the negative axis direction

Finding the Right Offset:

  1. Note your object's bounding box dimensions (visible in FreeCAD)
  2. If your object is centered at origin and you want to cut in half: Use offset = 0
  3. If your object is positioned elsewhere: Look at the coordinate where you want to cut

Option 2: Model Plane (Advanced, angled cuts)

Select any datum plane or planar face from your model:

Using Datum Planes:

  1. Create a datum plane first (if not already in model):

    • Go to Part Design workbench
    • Click Create datum plane (or Part → Datum → Datum Plane)
    • Position and angle the plane where you want to cut
    • Exit datum plane creation

  2. In the macro dialog:

    • Select "Model Plane" from Plane Type
    • Choose your datum plane from the dropdown
    • The offset field is disabled (plane position defines the cut)

Using Object Faces:

  • Any planar face on any object in your document can be used as a cut plane
  • Select from the dropdown: "Face: [ObjectName] (Face1, Face2, etc.)"
  • Useful for cutting along existing geometry

Step 4: Configure Magnet Holes

  • Diameter: The diameter of your magnet (mm)
  • For 6mm magnets: Use 6.2mm (adds 0.2mm clearance)

  • For 3mm dowels: Use 3.1mm (adds 0.1mm clearance)

  • Depth: How deep holes go into each piece (mm)

  • For magnets: Use magnet thickness + 0.5mm

  • For dowel pins: Usually half the dowel length

  • Number of Holes: Total number of magnet holes to create (default: 6)

  • Holes are evenly distributed around the perimeter

  • Recommended: 4-6 for small objects, 8-12 for large objects

  • Edge Clearance (Preferred): Ideal distance from hole edge to outer surface

  • Default: 2mm - holes are initially placed with this clearance

  • Edge Clearance (Minimum): Absolute minimum acceptable clearance

  • Default: 0.5mm - the smallest allowable clearance

Step 5: Execute the Cut

  1. Review all parameters
  2. Click "Execute Cut"
  3. Watch the progress bar
  4. Check status messages for any skipped holes

Step 6: Review Results

The macro creates two new objects:

  • [ObjectName]_Bottom - Lower piece with holes
  • [ObjectName]_Top - Upper piece with holes

Your original object is hidden (not deleted) - you can show it again from the tree view if needed.

Common Use Cases

Case 1: Large Print Split for Bed Size

Scenario: 300mm diameter object, need to split for 250mm print bed

Settings:

Plane: XY
Offset: 0 (if centered) or half the object height
Diameter: 6.2mm (for 6×2mm magnets)
Depth: 2.5mm
Number of Holes: 12
Clearance: 3mm

Case 2: Modular Terrain Tiles

Scenario: 100×100mm terrain tiles with magnetic edges

Settings:

Plane: XY or YZ (depending on desired split)
Offset: 50mm (half the tile dimension)
Diameter: 3.2mm (for 3×1mm magnets)
Depth: 1.5mm
Number of Holes: 6
Clearance: 2mm

Case 3: Angled Cut with Datum Plane (45° Wedge)

Scenario: Splitting a wedge-shaped console at a 45° angle

Preparation:

  1. Switch to Part Design workbench
  2. Create datum plane:
    • Click Create datum plane
    • Rotate 45° around X-axis
    • Position at desired cut location
  3. Name it "CutPlane45" (optional but helpful)

Settings:

Plane Type: Model Plane
Model Plane: Plane: CutPlane45
Diameter: 6.2mm
Depth: 3mm
Number of Holes: 8
Clearance: 3mm

Advanced Tips

Creating Perfect Datum Planes

For Angled Cuts:

  1. Simple Rotation Method:

    • Part Design → Create datum plane
    • Reference: XY plane (or any base plane)
    • Attachment offset → Rotation:
      • Around X: Tilts forward/back
      • Around Y: Tilts left/right
      • Around Z: Spins horizontally

  2. Align to Edges/Vertices:

    • Attachment mode: "Three points"
    • Select 3 points on your model
    • Plane will pass through all three points

Magnet Installation Tips

After printing:

  1. Test fit magnets - they should slide in smoothly
  2. If too tight: Use a drill bit to clean out the holes
  3. If too loose: Use CA glue or epoxy to secure
  4. Check polarity! - Mark magnet orientation before gluing