From Approved Files to CNC-Machined Parts

CAD means Computer-Aided Design.

CAD files contain the digital geometry that defines the component shapes, dimensions, holes, pockets and other required details.

CAM means Computer-Aided Manufacturing.

CAM is the programming process used to convert approved CAD geometry into toolpaths and machining instructions for the CNC router.

CNC means Computer Numerical Control.

The CNC router follows the programmed movements created through CAM. It does not independently decide which cutter to use, how fast to run or how the material should be machined.

In simple terms:

• CAD defines the component

• CAM defines how it will be machined

• CNC performs the programmed movement

A toolpath is the programmed route followed by the cutter.

It includes more than the visible component outline. A toolpath can also define:

• Cutting direction

• Machining depth

• Number of passes

• Entry and exit movements

• Cutting order

• Tool changes

• Tabs or other part-retention methods

Different operations on the same component may require separate toolpaths.

Nesting is the arrangement of components across a sheet or piece of material before machining.

A production nest considers:

• Component quantities

• Material size

• Grain or face direction

• Spacing between parts

• Cutter access

• Workholding

• Part identification

• Material yield

A tightly packed nest is not always the safest or most efficient machining layout.

A nested CAD file still requires CAM programming before it can be machined.

These terms describe different machining operations.

Profile cutting follows the inside or outside outline of a component, often cutting through the complete material.

Pocketing removes material from a controlled area without cutting through the full thickness.

Drilling or hole machining produces holes at defined positions and sizes.

Engraving produces shallow text, lines, markings or identification details.

Chamfering machines an angled edge or bevel using suitable tooling.

3D milling produces curved or varying-depth surfaces using toolpaths that move across several levels.

One component may require several different operations, cutters and machining depths.

What Are Feeds, Speeds and Passes?

Feed rate is the speed at which the cutter moves through the material.

Spindle speed is how quickly the cutter rotates.

Pass depth is the amount of material removed during one level of machining.

A deep feature may be completed over several passes rather than in one cut.

These settings are selected around:

• Material

• Cutter type and diameter

• Machining depth

• Component geometry

• Workholding

• Chip and dust removal

• Required edge or surface result

There is no single setting that suits every cutter and material.

Workholding is the method used to keep the sheet and individual components flat, stable and secure during machining.

Depending on the material and job, this may involve:

• Vacuum hold-down

• Mechanical fixing

• Tabs

• Leaving surrounding material in place

• A carefully planned cutting order

• Additional support for small or flexible parts

Reliable workholding is essential. A correctly programmed cutter cannot produce a dependable result if the material or component moves during machining.

Tabs are small sections of material intentionally left between a component and the surrounding sheet.

They can help prevent smaller parts from moving after most of their outline has been cut.

The tabs are removed after machining.

Tabs are not required on every job. Their use depends on the component size, shape, material, workholding and cutting strategy.

Each machining operation removes material and can reduce the amount of sheet remaining to hold the parts securely.

The cutting order is planned to preserve support and hold-down for as long as practical.

For example:

• Pockets and internal features may be machined before the outside profile

• Small components may be cut later

• Some areas may remain connected temporarily

• Tool changes may be arranged to reduce unnecessary handling

• Parts may be grouped to maintain sheet rigidity

The safest sequence is not always the shortest-looking sequence.

The component geometry may remain unchanged while the production method changes.

Different CAM programming may be required when the following changes:

• Material

• Material thickness

• Cutter

• Required edge or surface result

• Component quantity

• Sheet size

• Grain or face direction

• Workholding

• Machining depth

• Available surrounding material

A plywood component, acrylic component and aluminium component should not be assumed to use the same cutters or cutting settings simply because the geometry is identical.

The cutter is selected around the material, thickness, component geometry and required result.

Larger cutters can generally remove material more efficiently and complete deeper passes, but they cannot produce very fine internal details.

Smaller cutters can reach tighter geometry and detailed joinery, but usually require shallower passes and longer machining time.

The smallest cutter that fits the drawing is not automatically the best cutter for the complete job.

A test cut may be recommended where the result depends on:

• Actual material thickness

• Slot or tab fit

• Cutter radius

• Pocket depth

• Material behaviour

• Workholding

• A critical assembly detail

• A new production method

The test confirms a specific machining detail before the full quantity is produced.

It does not replace unresolved design work or missing dimensions.

No.

The machine is monitored while it is operating.

The operator watches:

• Material movement

• Vacuum hold-down

• Cutter condition

• Dust and chip removal

• Heat buildup

• Machining progress

• Small or loose components

• Completed operations

The job may be paused if material moves, extraction becomes blocked, a component becomes loose or another production issue develops.

Materials respond differently to cutters, heat, speed, workholding and waste removal.

For example:

• Acrylic can build heat and begin to melt

• Suitable aluminium can heat up and adhere to the cutter

• MDF produces large amounts of fine dust

• Timber and plywood can splinter or respond differently with the grain

• Plastics can flex, heat or create long chips

• Bowed sheets can reduce reliable vacuum hold-down

The cutter, speeds, passes, toolpaths and monitoring must suit the actual material and required result.

Component size alone does not determine production time.

A smaller part may require:

• Fine tooling

• Tight internal geometry

• Many holes

• Deep pockets

• Several machining depths

• Multiple cutters

• Repeated tool changes

• Slower movement

• Difficult workholding

• Detailed checking

A large simple profile may machine faster than a small component containing many detailed operations.

After machining, completed components, offcuts, dust and chips must be removed safely.

The machine bed and vacuum surface are cleared before new material is loaded so the next sheet can sit flat and achieve reliable hold-down.

Production time can include:

• Unloading components

• Separating waste

• Clearing dust and chips

• Cleaning the machine bed

• Checking the next sheet

• Reloading and re-establishing hold-down

These tasks are part of completing the job, not separate from CNC production.

Not automatically.

Cut It supplies CNC-machined components to the agreed production scope.

The machining may leave:

• Tool marks

• Tabs requiring removal

• Edges requiring sanding

• Dust or loose fibres

• Surfaces requiring further preparation

Suitable sanding, edge preparation, laminating, edgebanding, assembly or finishing may be separately quoted under Build It.

For a repeat order, provide:

• The current quantity

• The required date

• The approved revision

• Confirmation of the material

• Details of anything that has changed

Where the geometry, material and production requirements remain unchanged, retained production information may reduce repeated setup decisions and clarification.

A repeat order should not be assumed to be unchanged unless the current requirements are confirmed.

The current geometry, material, quantities and machining requirements are confirmed.

Williamstown CNC Works then prepares the nesting, CAM, tooling, workholding and machine setup required for the job.

Any remaining production questions are resolved before machining begins.

No.

The customer provides or approves the component geometry and required machining features.

Williamstown CNC Works creates the CAM and toolpaths used to control the CNC router.

The customer approves:

• Component geometry

• Dimensions

• Material

• Thickness

• Quantities

• Machining requirements

• Intended use

• The current revision

Williamstown CNC Works determines the CAM, tooling, workholding and machining method used to produce those approved components within the agreed scope.

Where engineering, structural, architectural, marine, regulatory or specialist approval is required, it must be provided by an appropriately qualified party.

The completed components are checked against the agreed production scope, grouped where required and prepared for collection or agreed delivery.

The customer can then:

• Assemble and finish the parts

• Send them to another trade

• Use them within a larger project

• Reorder an unchanged production batch

• Continue into separately quoted Build It services