Machine

CNC Milling

CNC Milling

A CNC router is a large and powerful router precisely controlled via computer software. It can cut and mill various hard materials such as wood, composites, aluminium, plastics, and foams.

Some commonly referred to terms to keep in mind are:

Term	Description
Bit	A cylindrical formed blade of specific design and diameter that is attached to the operating head of router, and the primary tool for cutting material.
Stock	The original form of a material, prior to cutting.
Part	The fabricated end result form.
Toolpath	The specified instruction of the path the CNC router is programmed to follow and the bit to be used; specific to each job. Translated into a GCode format when relayed to the router machine.

Operation

A CNC Router uses a rotating bit to subtractively remove material from stock in order to shape a part by moving the router through the material in three axis or directions [X, Y and Z, or left, right, up and down]. While the shear power of the router allows for the 2 axis cutting of heavy and large scale materials, moving the router in all three directions simultaneously allows the creation of three dimensional and curved parts such as site topography and curvilinear forms.

The CNC Router requires specific instructions to control the machine in the form of a toolpath.

To fabricate a part, the machine will require control geometry to specify a machining operation. Below is a list of the operations available, the following pages describe more detail about their use.

To fabricate your part you will need to have a conceptual understanding of the different operations and their respective suitability.

Please familiarise yourself with these operations prior to designing as the machine limitations can be a design constraint.

Machining	Suitability
2 AXIS	Cutouts, engraving, ‘2D’ work.
3 AXIS	Topography, surfaces, ‘3D’ work.
4 AXIS	360° Rotational Milling, 3D geometry.

NOTE: Control geometry must be clean and well-modelled. Please refer to the pages titled Controlling Geometry - Do’s & Don’ts for information and useful commands. Again, read these prior to designing as poorly constructed lines and surfaces will not be able to be milled.

MultiCam SR2412vi

Our CNC Machine

MultiCam SR2412vi

The Fab Lab utilises a large CNC router made by Multicam, a local Melbourne company.

The MultiCam CNC router has a large bed surface area and the capability to use a variety of tools, allowing the machine to cut and shape a wide range of materials of varying sizes.

• Materials: Timber, Foam, Plastics, Thin metal

• Cutting Area: 2400mm L x 1200mm W x 100mm D

Multicam SR2412 vi

Machine & Material Capabilities

The machine is capable of cutting a range of materials including metals. Fab Lab stocks the following materials regularly:

Material	Maximum Thickness
MDF	6mm, 9mm, 12mm, 25mm
CD Non Structural Ply	12mm, 18mm
Furniture Grade Ply	12mm, 15mm, 18mm, 24mm
Film Faced Ply	12mm
XPS Extruded Polystyrene	30mm, 50mm, 75mm, 100mm
Aluminium Sheets	0.6mm, 0.8mm, 1.2mm, 1.6mm

*Materials need to be on the approved materials list. Please see Custom Material for more information.

Custom Material

If you would like to cut a material we don’t already stock, come and see us in the Fab Lab before you buy your material so we can make sure the material is safe and possible to cut.

Outsourced hardwood may be brought in for CNC milling, and the Workshop provides facilities for laminating if required, prior to milling.

The Fab Lab is able to accept bulk deliveries, please co-ordinate at least two weeks prior to submitting your job.

NOTE: Students submitting their own material must also supply sufficient material for testing, calibration of settings or re-milling in case of malfunction. - Please see the MSDS page for more information - HERE

Why Use the CNC Machine?

CNC routers are commonly used in industries for cabinet making, sign making, woodworking and furniture fabrication, due to their ability to cut and shape large parts of varying geometry, quickly, precisely and cheaply.

Today, CNC machines have become heavily incorporated into industries such as:

• Industrial production: Cabinet making, sign writing, woodworking and furniture fabrication.

• Architecture: Custom facade panels, joinery, moulds for casting, placing fold lines, topography models.

• Education: 1:1 structural prototypes, site models, large custom components.

Limitations

Limitations

Small Parts

The CNC router is an industrial level fabrication machine, not designed to mill and cut small parts. Some parts may be possible, however please consult with Fab Lab staff to determine the most appropriate machine.

For smaller objects and models consider using the 3D printer, laser cutters or the machine workshop.

Precision

Tolerance of parts

The CNC Router is capable of being programmed up to the surface detail of 0.001mm.

It is important to tolerance your 'female' parts. Offset between 0.1-0.3mm to ensure they fit with out extra need of sanding or filing.

However, the milling of parts is limited by:

• The ability of the material to be held to the table via a vacuum pump. This sucks material to the cutting bed, prohibiting movement while the router runs. Small parts, having less surface area will move around and be less accurate.

• The relative strength/breaking properties of the material you are milling. For example, lower grade plywood tends to chip whilst foam will result in a smooth surface.

Bit Size

Tool bit size effect

The Fab Lab has a range of bits from 3mm to 12.7mm diameter. Most jobs are processed using a 6.35mm bit or larger. Only limited specific tasks can be achieved by the smaller bits, and must have consulted with Fab Lab staff beforehand. Therefore most jobs must allow enough space to accommodate a 6.35mm bit or larger.

Grooves, notches, slots and holes must not be smaller than 3mm.