3.7 Preparation of materials

• show knowledge of available market forms, types and sizes.

• understand methods of cutting by use of hacksaw, guillotine, tenon saw, cross-cut saw, panel saw and portable power tools

• understand the use of datum surfaces/lines/edges and be able to produce them by planing or filing

• explain the preparation for machine processes and safe methods of securing materials to work surfaces, work tables, faceplates, lathe chucks and between centres on a lathe.

Wood can be obtained in a variety of forms from the raw material (the tree itself) to various shapes and sizes of processed timber.

However, a single piece of wood can be no bigger than the tree it comes from unless it is engineered or laminated.

Common forms include planks, beams, square and rectangular section, dowel and various manufactured boards which are usually available in sizes up to 2 metres x 1 metre (sometimes even larger). Wood can also come in mouldings or profiles.

The stock form of plastics refer to the various shapes and sizes in which plastic materials are commonly purchased by manufacturers and designers. These forms include sheets, rods, tubes, granules, powder, and films. Stock forms are standardised, making it easier to transport, store, and cost the material, as well as providing a clear understanding of available shapes for design purposes. 

• Sheets: Available in various thicknesses and can be used for signage and various other applications, such as laser cutting. 

• Rods: Similar to wooden dowels, they can be used for construction and in machinery. 

• Tubes: Used for piping and other applications. 

• Granules / Pellets: Used in processes like injection moulding, blow moulding and extrusion, where they are melted and shaped. 

• Powder: Can be used in processes like dip coating, where metal objects are covered in a plastic coating. 

• Foams: Used for modelling, packaging, and other applications. Styrofoam (blue foam) comes in standard sizes.

• Profiles: Specialised shapes like hollow sections, square bars, etc

Different cutting methods for materials, like those used with a hacksaw, guillotine, tenon saw, cross-cut saw, panel saw, and portable power tools, each have unique techniques for achieving specific results. 

Hacksaws are primarily for metal, utilising fine teeth and steady strokes, while guillotine style cutting involves a lever mechanism for paper. Tenon and cross-cut saws, used in woodworking, are intended for woods and used for precision cuts or cutting across the grain, respectively. Panel saws are for large sheet materials such as manufactured boards, and portable power tools (Jigsaw, Drill) offer a wider range of cutting power and versatility. 

Datum surfaces / lines / edges are fundamental in engineering for defining reference points in a part's geometry. They are used to ensure consistency in measurements and maintain desired relationships between features during manufacturing and inspection. Think about your Onshape modelling and dimensioning from Datum planes. Datum features can be created using planing or filing, depending on the desired precision and the material being worked with. 

Understanding Datum Surfaces / Lines / Edges:

Purpose: Datums serve as reference points for measuring and locating other features on a part. They establish a coordinate system for defining the part's geometry and ensuring its functional performance. 

Types: Datums can be points, lines, planes, or axes, and they are derived from real features on a part. 

Importance: Datums are crucial for ensuring that parts meet design specifications and can be manufactured accurately and consistently - quality assurance. 

There are countless measures that need to be considered for machine processes. Depending on the machines in use and the materials

involved, measures are generally safety rules. However, there are some standard safety practices all industry, schools and workers should 

follow to avoid injuries:

Train all extensively.

Every person working iwith machines must be trained on the equipment present, even if they may not use it frequently. A thorough 

knowledge of tools and parts is necessary to maintain safety standards.

Wear personal protective equipment (PPE)

PPE provided by the employer should meet all safety standards The most important types of equipment include:

• Goggles – Wearing goggles while operating machinery protects eyes from flying debris and sparks. This is true even for workers not operating machines, as others engaged in work could cause debris to fly.

• Gloves – Gloves should be worn to protect skin and nails, especially if workers are using harsh chemicals. Thick gloves can also protect against rust or cuts from tools.

• Respirators – In workshops with potentially harmful fumes.

• Ear defenders - in workshops when using machinery to cut materials that creates a loud environment

Do not wear hazardous clothing.

While PPE is required, you should actively avoid some clothing items in a workshop for safety purposes. The following items could drastically 

increase the potential for injury:

• Loose-fitting clothing – Anything too loose could be sucked or fed into a machine or caught on equipment.

• Open-toed shoes – Shoes that expose the feet must be avoided as they increase the surface area exposed to harmful chemicals, tools and fumes.

Never force machines to cooperate.

Sometimes, stubborn machines may feel stuck, and you may be tempted to force materials into or out of them. This is highly dangerous and 

could result in a machine malfunction. Feeds should be operated as intended, not forced to speed up or slow down.

Never work alone.

Working in a workshop alone is dangerous, as there is no one to help you if a machine backfires or something goes wrong.

Keep walkways and exits clear.

Paths between machines and all exits must be clear. This eliminates the potential that someone trips on tools or is unable to exit in the event

of an evacuation or emergency.

Keep workspaces clear.

Workbenches must be clear of debris, garbage, and extra tools during working hours. Any clutter can become a safety hazard. Every item in 

a workshop should have its designated place and remain there unless directly in use.

Inspect machines before each use.

Prior to using any machine, workers or technicians should inspect it for hazards. Make sure the previous user shut down the machine 

properly and there are no exposed sections, parts or wiring that could cause malfunction. Strange sounds could indicate a problem also.

Leave machines clean after use.

After using a machine, aim to leave it better than you found it. This means inspecting thoroughly to ensure the machine has been turned off 

properly and completely, along with cleaning all parts that may have been dirtied in use. Excess debris buildup can decrease a machine’s 

functionality over time.

Report all injuries to management.

In the unfortunate event that an injury does occur, it must be reported to a teacher or management. 

In school workshops, vices and clamps are used to secure materials to work surfaces, to prevent movement during tasks like sawing, cutting, drilling, or sanding. This ensures stability and prevents accidents or inaccurate work. 

Clamps and Vices (Wood vice and Metal Vice):
These are common tools for securing materials to work surfaces or to hold materials. They are designed to hold materials firmly in place, preventing them from shifting or moving while being worked on. 

Types of Clamps and Vices:
Various sizes and types of clamps and vices are available, offering different clamping forces to suit different materials and tasks. 

Importance of Securing Materials:
Securing materials is crucial for safety and accuracy. When materials are not securely held, they can shift, potentially causing accidents, injuries, or inaccurate cuts. 

Other Clamping Methods:
Depending on the material and the specific task, other clamping methods like specialized work surface fixtures (Bench Dogs) or magnetic clamps might be used. 

Securing workpieces on a lathe using 'faceplates', 'chucks', and 'between centres' involves specific methods to ensure a stable and accurate workpiece. 

Faceplates utilise bolts and clamps within slots to hold large or irregularly shaped pieces. 

Chucks, like three-jaw self-centering chucks, grip workpieces with jaws that move inward or outward, accommodating round or hexagonal shapes. 

Between centres, a workpiece is held by two points on each end, with a live centre in the headstock and a tailstock supporting the other end. 

• Faceplates are used for holding workpieces that are too large or irregularly shaped to be easily held in a chuck or between centres. 

• They are secured to the lathe spindle and utilise slots and bolts to hold the workpiece, ensuring the workpiece's axis is aligned with the lathe centres. 

• Bolts, clamps, and dogs are commonly used to hold the workpiece securely. 

• Lathe chucks are a versatile and accurate method of holding workpieces for turning. 

• Three-jaw self-centering chucks are a popular type, automatically centering round or hexagonal workpieces by adjusting the jaws. 

• Other chuck types include collet chucks, which grip cylindrical workpieces with collets, and four-jaw independent chucks, which provide independent jaw control for accommodating irregularly shaped workpieces. 

• This method supports the workpiece between a live centre in the headstock and a tailstock centre - see diagram below.

• The tailstock center supports the other end of the workpiece, allowing for turning operations.