Metal

There are three main types of metal, ferrous, non-ferrous and alloy.

Ferrous Metals
Contains iron and therefore rusts and is magnetic. Examples are Cast Iron and Steel.

Non-Ferrous Metals
These metals do not contain iron and are usally more expensive, and they dont rust. Examples are Aliminum and Copper.

Alloys
Alloys are a mixture of two or more materials. They are mixed so that the properties of two materials can be combined. By combining them you can change the:
-Resistance to corrosion
-Melting Point
-Colour
-Strength
-Electrical properties
-Thermal properties
-Flow of the melted metal

Examples of Non-Ferrous Alloys are Brass and Bronze. Examples of Ferrous Alloys are Stainless steel and High speed steel.

Work Hardening and Heat-Treating Metals

Annealing
The metal is heated and cooled slowly, so that is becomes soft and relieves stress. This make it less brittle and more ductile, so it is easier to work.

Hardening
Carbon steel is heated, until the carbon crystals move out of position. The material is then quenched so the crystals cannot move back into place. This causes internal stress which hardens and strengthens the metal.

Tempering
Tempering removes the stress from a harden piece of steel. this makes it less brittle but still hard. the metal is polished until you can see the surface of the metal and then heat is applied. When the metal reaches the desired colour, it is quenched.
As the tempering temperature rises, the materials hardness is reduced but its toughness is increased.

Manufactured Boards

Manufactered boards are cheap and come in all shapes and sizes. They can be cut into any shape and are always exact. There are no knots and can be laminated to look like real wood.

Plywood
Plys are placed on top of one another with perpendicular grains. This strengthens the board from all angles. This makes it quite strong.

Chip Board
Chips, from waste wood, are stuck together with resin. Very economically friendly as it reuses waste. Moderatly strong, light weight, but absorbs water and will swell up.

Sterling Board
Really cheap board used on building site. Very weak. Used to cover windows. Made from waste wood.

MDF
Wood fobres stuck together with urea formaldahyde. Toxic when burnt or cut. Can be flexible and is very cheap.

Block Board
Thicker and heavier than plywood, made from long thick strips of waste wood, then laminated. Quite strong but rough and ugly.

Hexa Board
Very grippy, used for outdoor flooring. Quite strong.

Woods

Most of the wood used accross the world comes from America or the Far East. Most of this is from rainforests. Some companys are destroying these rapidly but others, supported by FSC, create sustainable enviroments and plant a tree for every tree cut down. They also respect the surrounding wildlife, you know whether the product you using is from a sustainable source as it will bear the FSC logo.

When working with woods you must consider structure, grain and cost. Also wether you by it PSE (plain, squared and edged) or just straight from the tree where it will be rough and splintery.

Woods are either hard woods or soft woods, but this doesnt nessicarily mean they are hard or soft. Hard woods have more gymnosperms and are from decidous trees, they take longer to grow (60-100)and are therefore more expensive. They are usally harder as they have closer grains, but there are exception such as balsa with you can dent with you fingers.

Soft woods are from coniferous trees and take less time to grow. They are alot cheaper, can produce long lengths but are open grained and weaker than hardwoods.

Woods are aleays seasoned. This means they dry in a controlled way. This stops its from cupping, bowing or twist.

Examples of softwoods are scots pine, spruce and douglas fir.

Examples of hardwoods are beech, oak, ash, mahagany, teak.

I Should Have Never Bought...

my Ei Systems 3083 Laptop.

I had wanted a laptop for some time, and went equiped with £400 to my local PC World. I browsed through the hundreds of laptops with the help of some staff, all eager to sell me whatever they could. My choice was finally settled on a bulky, squared shaped laptop. I decided to buy it as it had a large amount of ram compared to the contrating laptops in my price range. Also because there was an offer on the machine, which meant, by applying for insurance, I could get the laptop, a £30 laptop case, 50 DVDR's and a spare battery for £350.

Once getting it home and setting it up I was excited to realise that the laptop came with a free memory stick. Only when I tried to connect to the internet did I realise that it was a USB network adapter! I had spent all this money, which I had saved for months, to be confronted with a bulky laptop with an ugly adapter sticking out the back. As well as looking ugly you have to be really careful you dont put the laptop down in the wrong way because otherwise the fragile adapter will snap.

When this did happen I had to ring a call centre in India to order a new one, and when the package arived it wasnt inside! It finally arrived about a month later and I have been steady with it ever since.

Other problems are that my laptop regularly overheats. If you leave it on for any more than an hour the laptop becomes to hot to touch on the bottom, honestly you could frie an egg on it. Im suprised nothing inside is damaged. After a few hours even the keys are too hot to touch!

My last complaint is that my left key has fallen of. Trying to play games on the laptop is difficult as the button continuously flicks out.

Besides all this I still own the laptop and it still works and I use it most days, I find if it stops the best tactic is just to hit it, hard.