Drawing standards, protocols and conventions Flashcards
BENEFITS OF DRAWING STANDARDS
Simplified through the use of symbols.
Drawings are quicker to produce because symbols are used.
Language barriers are eliminated because it is a common worldwide language.
LINE TYPES
A thick continuous line shows visible outline.
A thin continuous line shows projection/construction lines.
A thin broken line shows hidden detail.
A thin chain line shows a centre line.
A thin chain line with thick ends is a cutting plane and shows where an object has been cut.
A thin double dashed line is used as a fold line to indicate where a surface development should be folded.
Thin 45^ cross hatching shows the cut surface from the cutting plane.
Screw threads are shown as double lines. The second line is broken. If it is on the inside, it’s an external screw thread. If it is on the outside, it is an internal screw thread. M stands for metric.
Kneeling shows a criss cross pattern on a surface to provide grip.
A circle with a line shows diameter (only used on a full circle).
R means radius ( only use radius when it’s a semi circle, curved corner or arc).
A/F, A/C is across flats and across corners when dimensioning a hexagon.
A square is a square section.
ASSY stands for assembly.
PRT stands for partt.
Third angle projection symbol is added to diagrams to show the layout.
DIMENSIONING RULES
Each dimension should only be shown once.
They should always be placed so they can be read from the bottom of the page or the right hand side.
Always measure in mm unless instructed otherwise.
Figures should not touch outlines, centre lines or dimension lines.
DIMENSIONING
Dimension lines: Placed outside visible lines. Arrowheads should be slim and small and touch projection lines.
Overall dimensions should be placed further away.
Intermediate dimensions are placed in line and known as chain dimensions.
Figures on vertical lines should be places so they can be read from the right.
When more than one dimension is taken from a line, it’s called a datum line.
When more than one dimension is taken from the datum line, the dimensions are in parallel.
Projection/leader lines: Leave a small gap between outline and projection line. These lines enable the dimension. Leader lines should always extend beyond dimension lines to not confuse with the drawing.
SCALE FOR DIFFERENT TYPES OF PLANS
Location plan: 1:1250
Site plan: 1:200
Floor plan: 1:50
WHAT IS A LOCATION PLAN
It identifies the location for the proposed building and shows its surroundings. It helps the builder plan the building.
Roads, streets, fields are shown.
WHAT IS A SITE PLAN
Shows the site boundary and the outline of the new building.
Paths, roads and neighbouring plots are also shown.
Allows builder to mark out the site, lay pipes and build manholes.
WHAT IS A FLOOR PLAN
A type of sectional view which represents a plan view of the building with the roof removed.
It shows the arrangement of rooms, positions of windows and doors.
They are used by builders, plumbers, electricians and joiners to plan the construction work.
May include dimensions, layout of water pipes and electrical cabling.
ELEVATIONS AND SECTIONS OF A BUILDING
Sections show how windows fit into walls, the floorboards and joints and the types of material used throughout.
An elevation is used to show the style of the house, the external appearance and the positions of doors and windows.
BUILDING SYMBOLS
building symbols x
