Stock forms, types and sizes Revision Notes for AQA GCSE Design and Technology

Stock forms, types and sizes

What are stock forms?

Stock forms refer to the range of commercially available timber and manufactured boards that come in standard sizes and specifications. These pre-cut materials offer significant advantages for both designers and manufacturers, making them a popular choice in woodworking projects.

The main benefits of using stock forms include being more cost-effective than custom-cut timber and having better availability since they're mass-produced. Additionally, designers find it much easier to incorporate these standardised dimensions into their project plans, which helps streamline the production process.

Note

The standardisation of timber dimensions isn't just convenient - it's a key factor that drives down costs across the entire woodworking industry. When suppliers can focus on producing large quantities of standard sizes, they achieve economies of scale that benefit everyone in the supply chain.

Available stock forms of timber

When working with natural timber, you'll find that most commercial suppliers offer their wood in standardised stock forms. This approach makes sense for several reasons - it reduces costs for both suppliers and customers, and it simplifies the design process since you can plan around known dimensions.

Rather than having to specify custom cuts for every piece of timber needed, designers can select from the range of available standard sizes. This not only speeds up the ordering process but also helps avoid the need to alter width and thickness measurements whenever possible, though length can typically be adjusted more easily.

Standard sizes and planks

Understanding planks

Planks represent one of the most common stock forms you'll encounter. These are long, flat pieces of timber that come with standard width and thickness measurements, though they're available in two different grades of finish.

The standard lengths for planks follow a consistent pattern: 1.80 m, 2.10 m, 2.40 m, 2.70 m, 3.0 m, and 3.30 m. This range of lengths allows for flexibility in project planning while maintaining the cost benefits of standardised production.

Grade of finish

The grade of finish refers to how smooth and refined the timber surface is, which directly affects where and how the material should be used.

Important

Understanding Timber Finishes

Rough sawn timber has not undergone any planing process, leaving it with a rough texture that's quite noticeable to touch. This rougher finish makes it more suitable for exterior work where the surface texture is less critical, and the natural weathering will occur anyway.

Planed all round (PAR) timber has been processed through planing machines, resulting in a smooth surface that feels pleasant to touch. The dimensions of PAR timber are also more precise due to the machining process. This higher-quality finish makes PAR timber the preferred choice for interior work where appearance and feel matter more.

Standard sizes of manufactured boards

Manufactured boards follow their own sizing conventions, starting with a minimum thickness of 3 mm and increasing in regular steps such as 6 mm, 9 mm, and so on. When veneer is applied to these boards, the starting thickness increases to 4 mm.

The full-size standard for manufactured boards is quite specific: 2440 mm long by 1220 mm wide. This large format allows for efficient cutting of smaller pieces while maintaining material economy.

Understanding veneer

Veneer plays an important role in manufactured boards and deserves special attention. A veneer consists of a very thin layer of timber that has been carefully removed from a tree, typically measuring between 0.4 and 1.5 mm in thickness.

Note

Veneer Production Process

The process of creating veneer often involves rotary cutting, where the log is rotated against a blade to peel off continuous thin sheets, much like unrolling paper from a roll. This technique allows for the efficient production of large, continuous sheets of veneer that can then be applied to manufactured board substrates.

Standard mouldings

Mouldings represent a specialised category of stock forms - these are lengths of timber that have been machined into specific shapes for decorative or functional purposes. The beauty of mouldings lies in their variety, as they're available in many different profiles to suit various design needs.

Dowels

One particularly important type of moulding is the dowel, which features a circular cross-section with a precisely specified diameter. Dowels serve various purposes in woodworking, from structural joints to decorative elements, and their round shape makes them ideal for applications requiring smooth insertion into drilled holes.

Decorative mouldings extend far beyond dowels, offering an extensive range of shapes and profiles that can enhance the visual appeal of woodworking projects.

Example

Practical Application: Choosing the Right Stock Form

When designing a bookshelf project:

Use PAR planks for visible shelves (smooth finish for interior use)
Select rough sawn timber for the back panel (exterior-grade, hidden from view)
Choose manufactured boards for large panels where cost-effectiveness is important
Incorporate decorative mouldings for edge treatments and visual interest

Why designers choose stock forms

The decision to use stock forms in design work stems from practical considerations that benefit the entire production process. Cost-effectiveness stands as the primary driver - stock forms are typically much cheaper than having timber cut to custom specifications because they take advantage of mass production economies.

Availability represents another crucial factor. Stock forms are readily available from suppliers, which means shorter lead times and more predictable project schedules. This reliability in sourcing helps ensure that projects can proceed without delays caused by waiting for custom timber processing.

The ease of sourcing also extends to the design phase, where knowing that specific sizes are readily available allows designers to create more practical and achievable designs. When you design around stock dimensions, you reduce both costs and complexity in the manufacturing process.

Summary

Key Points to Remember:

Stock forms offer cost advantages - They're more economical than custom-cut timber due to mass production benefits and readily available from suppliers
Two main grades of finish serve different purposes - Rough sawn works well for exterior applications, while PAR (planed all round) provides the smooth finish needed for interior work
Standard dimensions streamline production - Planks come in set lengths from 1.80m to 3.30m, while manufactured boards follow the 2440mm x 1220mm standard
Veneer adds versatility - These ultra-thin timber layers (0.4-1.5mm thick) allow for decorative surfaces on manufactured boards
Mouldings provide shaped solutions - From circular dowels to decorative profiles, these pre-machined stock forms offer ready-made solutions for specific design needs

Stock forms, types and sizes (AQA GCSE Design and Technology): Revision Notes