MYP Design Scale and Proportion Notes

A Scale Is a Promise About Size

1. A scale is the fixed ratio between a length on your drawing and the same length on the real object.
2. It is always written drawing size first, real size second, so the left hand number belongs to the paper.
3. Stating a scale is what lets a reader lay a ruler on your drawing and work out a real dimension you never wrote down.
4. Scale applies to the whole drawing at once, so you cannot shrink the awkward part to make it fit.
5. The dimensions you write on a drawing are always the real sizes, whatever scale the drawing itself is at.

Reading the Ratio the Right Way Round

1. 1:1 is full size, and a 60 mm edge is drawn 60 mm long.
2. 1:2 is half size, so the object is twice as big as what you see on the page.
3. 1:10 is a tenth size, which is how a 1200 mm desk fits comfortably across an A4 sheet as 120 mm.
4. 5:1 runs the other way and is five times full size, used for small parts such as a 3 mm spring clip or a watch gear.
5. If the big number is on the right the drawing is a reduction, and if it is on the left the drawing is an enlargement.
6. Writing the ratio backwards turns a 900 mm chair into a 0.9 mm chair, which is the sort of error nobody catches until the wood is cut.

Getting Real Dimensions Out of a Scaled Drawing

1. To go from paper to reality on a reduction, multiply what you measure by the right hand number of the ratio.
2. A line measuring 34 mm on a 1:5 drawing is 34 × 5, so 170 mm on the real object.
3. To go from reality to paper, divide instead: a 1800 mm bench at 1:20 is drawn 90 mm long.
4. On an enlargement the arithmetic flips, so 60 mm measured on a 5:1 drawing is a real length of 12 mm.
5. Check every answer against common sense before you trust it, because a door handle that works out at 2 metres is a slipped decimal point.

Choosing a Scale That Fits the Page

1. Pick the largest scale at which the object plus its dimension lines still fit inside the sheet margins.
2. An A4 sheet gives you about 180 mm by 260 mm of usable space once margins and the title block are taken out.
3. Stick to the standard reductions 1:2, 1:5, 1:10, 1:20, 1:50 and 1:100, and the standard enlargements 2:1, 5:1 and 10:1.
4. Odd ratios such as 1:3 or 1:7 are legal but slow everyone down, and slow arithmetic is where mistakes come from.
5. A room plan usually needs 1:50, a piece of furniture 1:10 or 1:20, and a phone case 1:1.

A Scale Bar Survives the Photocopier

1. A scale bar is a small ruler drawn on the sheet itself, marked off in labelled divisions.
2. Draw it 0 to 100 mm in 10 mm steps for product work, or 0 to 1 m in 100 mm steps for furniture and interiors.
3. The moment a drawing is photocopied at 70 per cent or dragged smaller on a screen, the words "scale 1:2" become untrue.
4. The bar shrinks by exactly the same amount as the drawing, so it stays correct no matter what happens to the page.
5. A drawing that will be uploaded to your ePortfolio and viewed on a phone needs a scale bar, since nobody knows how large it is displayed.

Proportion Is Scale Without the Ruler

1. Proportion is the relationship between the sizes of parts, with no ratio written down and no measuring involved.
2. A drawing can be at a perfectly correct scale and still look wrong if one part was drawn out of proportion with the rest.
3. Real bodies set most proportions in product design: a chair seat around 450 mm high, a door handle around 1000 mm, a worktop around 900 mm.
4. Rectangles close to 1:1.6 tend to look settled, which is why so many phone screens, books and business cards land near that shape.
5. Putting a familiar object in the drawing, a hand, a pencil, a mug, lets a viewer judge proportion instantly.

Keeping Proportion Honest When You Draw Freehand

1. Start with a light box at the right overall shape, three wide by two high for example, before any detail goes in.
2. Divide that box into a faint grid of equal squares and place each feature in the square it belongs in.
3. Fix the overall size first and the small parts last, because an error in the box spreads to everything drawn inside it.
4. Turn the sheet upside down for a moment, since your eye stops recognising the object and starts seeing the shapes as they really are.
5. When a freehand sketch finally gets redrawn to a stated scale, you are turning a proportion you judged into a dimension somebody can build.