Pocket Toolpath: Definition, Example, and Usage in CNC Programming

A pocket toolpath is a CNC machining path used to clear out an enclosed area or cavity inside a part by removing material layer by layer. It guides the cutting tool to move inside the boundary of the pocket, efficiently hollowing it out.

How It Works

Imagine you want to hollow out a small box or a cavity inside a block of wood or metal. A pocket toolpath works like a careful painter filling in the inside of a shape, moving back and forth or in circles to remove all the material inside the boundary.

The CNC machine follows this path, cutting away the material layer by layer until the pocket reaches the desired depth. The tool moves inside the edges of the pocket, avoiding the outside walls, so it only removes material where needed.

This process is similar to scooping out the inside of a pumpkin, where you remove the inside without touching the outer shell. The toolpath ensures the tool covers the entire pocket area efficiently and safely.

Example

This example shows a simple G-code snippet for a pocket toolpath cutting a square pocket 20mm by 20mm to a depth of 5mm.

gcode

G21 ; Set units to millimeters
G90 ; Use absolute positioning
G1 Z5 F300 ; Move tool to 5mm above the surface
G1 Z0 F100 ; Lower tool to surface
; Start pocketing
G1 X0 Y0 F500 ; Move to start corner
G1 Z-1 F100 ; Cut 1mm deep
G1 X20 Y0 F300 ; Cut along X axis
G1 X20 Y20 ; Cut along Y axis
G1 X0 Y20 ; Cut back along X axis
G1 X0 Y0 ; Complete square
G1 Z-2 F100 ; Cut 2mm deeper
; Repeat passes until depth -5mm
G1 X20 Y0 F300
G1 X20 Y20
G1 X0 Y20
G1 X0 Y0
G1 Z-3 F100
G1 X20 Y0 F300
G1 X20 Y20
G1 X0 Y20
G1 X0 Y0
G1 Z-4 F100
G1 X20 Y0 F300
G1 X20 Y20
G1 X0 Y20
G1 X0 Y0
G1 Z-5 F100
G1 X20 Y0 F300
G1 X20 Y20
G1 X0 Y20
G1 X0 Y0
G1 Z5 F300 ; Retract tool

When to Use

Use a pocket toolpath when you need to remove material inside a closed shape or cavity, such as making a hollow space for a part to fit inside or creating a recess for screws or electronics.

Common real-world uses include machining pockets for molds, dies, electronic enclosures, or any part that requires an internal cavity. It is efficient for clearing large areas inside boundaries without damaging the outer edges.

Key Points

• A pocket toolpath removes material inside a closed boundary.
• It works by cutting layer by layer to the desired depth.
• It is useful for creating cavities, recesses, or hollow spaces.
• The tool moves inside the pocket edges, avoiding outside walls.
• Common in CNC milling for molds, enclosures, and mechanical parts.

Key Takeaways

A pocket toolpath clears material inside a closed area by moving the tool within its boundaries.

It removes material layer by layer until reaching the target depth.

Use it to create cavities, recesses, or hollow spaces in parts.

It helps protect outer edges while efficiently machining the inside.

Common in CNC milling for molds, dies, and electronic enclosures.