Engineering Drawing

Evaluation of Freehand design

The thing that inspired my first design was a picture of a neon light. I wanted to have several coloured lights in my design not just one uncoloured LED. In all of my conceptual designs there is some kind of curve or circle so I knew that my final design would include spheres. I chose the three spheres design out of my conceptual designs because it was the most professional and clean looking one. Also the shape appealed to me because it was pretty. At first my idea was to have the two lower spheres in different kinds of metal and then the top one a non-coloured light. But then I thought of the neon lights and how cool they were and decided to make all the spheres out of acrylic and let a different coloured LED light each one.

Materials Justification

I am going to use vacuum forming plastic to create my design because it is the best way to make my three spheres. Although it may be rather difficult to make all the shapes fit together there isn’t a way it would be easier, and by having a flat bottom on the circles we can make it work. The plastic I will use to make it (Acrylic) is relatively cheap. The polystyrene for the mold is cheap too. It is an ‘economical process’ so we won’t be damaging the environment too much, which is important. Overall it is a versatile and easy to use method that will be the best way to make my design happen.

Vacuum forming plastic

Vacuum forming, commonly known as Vacuforming, is a simplified version of thermoforming , whereby a sheet of plastic is heated to a forming temperature, stretched onto or into a single-surface mold, and held against the mold by applying vacuum between the mold surface and the sheet. Vacuforming is one of the most versatile and economical processes available for manufacturing returnable packaging and many other products.

The strengths of thermoforming are as follows:
. Parts have low internal stresses therefore good physical properties to work with.
. Lead time and mold changes are relatively short and easy to perform.
. Large part don't increase costs.

Suitable materials for use in vacuum forming are conventionally thermoplastics , the most common and easiest being High Impact Polystyrene Sheeting (HIPS). This is molded around a wood, structural foam or cast/machined aluminum mold and can form to almost any shape. Vacuum forming is also appropriate for transparent materials such as acrylic.

Final Design

My design has its three spheres on top of each other

small medium large

Final design in progress

Freehand design with annotations

Poacita

- A dense shiny fawn green (dead leaves are mixed in with fresh green ones) tussock -30 to 70cm tall
- Leaves tightly folded, leathery, smooth above, fringed with hairs along the margins below; tip sharp.
- Leaf sheath creamy brown, shiny, with rough margin.
- Ligule is leathery, very short and even.
- Flower heads (30-100cm) do not stand proud of leaves. Panicle is open, slender, rough, with twisted branches. Awns absent

Concept designs

Brass

Brasses have excellent resistance to corrosion that makes them a natural, economic first choice for many applications.

• Atmospheric exposure of the brasses results in the formation of a thin protective green "patina", a visually attractive feature in buildings.

• Brass will remain essentially unaffected for an unlimited period of time, i.e. it will not rust away like iron and steel.

• Seawater can be handled successfully providing the correct alloy is chosen, and there is a long history of the use of brass tube and tube fittings, valves, etc. in domestic plumbing, central heating, seawater lines, steam condensers and desalination plant.

• High tensile brasses containing manganese have particularly excellent resistance to atmospheric corrosion, continual exposure resulting in a gradual darkening of the bronze colour.

Copper

The density of copper is 8.92 g/cm³.
It is a redish brown colour.
Copper is second only to silver in its ability to conduct electricity.
Copper is also very ductile.

Brief

My client is Doctor Tony House. He needs a garden light to light up some poacita in his Coromandel home. I have made myself the stakeholder. The light must be self-powered and be able to charge all day and then automatically turn on at night. Because it is in the Coromandel it needs to be rustproof so materials such as stainless steel, plastic, aluminium, brass and copper might be good. The light must also be weatherproof / waterproof. It must be controlled by a switch as well so that it can be turned off at night if wanted. The cost must not exceed $60 and the light can be no taller than 500mm.