Presentation on theme: "Using our imagination we can sometimes make a reasoned guess as to what may be concealed inside an object. We may even be lucky enough to have a magic."— Presentation transcript:
Using our imagination we can sometimes make a reasoned guess as to what may be concealed inside an object. We may even be lucky enough to have a magic key to reveal information as to what is locked up inside the safe The key to revealing hidden information in a drawing is to know the British Standard rules on sectioning
In real life if we want to find what the inside of donut is like we cut through it to see what is inside. When the donut has been cut the surfaces where the knife has passed through are clearly visible. In graphic communication where a surface has been cut to reveal information then that surface representing a specific material or materials is cross hatched as indicated.
X X PLAN SECTION XX cutting plane line Cutting Plane lines should clearly show where a section has been is taken The drawings below show 3 views of a donut. A section XX is required to reveal that the centre of the donut is hollow. The section has been taken centrally through the PLAN. When the section line ‘cuts’ through the centre of the donut it also passes through an ‘air gap’ as well as solid material. When a section line passes through solid material these areas are cross hatched at 45º Cross hatching lines are evenly spaced and in the same direction when the material is the same N.B. Air gaps are not cross hatched END ELEVATION
PLAN ELEVATION 1. Draw the Magic 45º from the corner of the ELEVATION. 2. Project the the breadth of the PLAN onto the Magic 45º then down to the ground line. Ground Line 3. Project the height of the ELEVATION across to the END ELEVATION. 4. Project the top and bottom of the hole across to the END ELEVATION. 5. Darken the outline and the two lines to represent the top and bottom of the hole. 6. Cross hatch the top and bottom areas at 45º to show the cut surfaces of the section. SECTION XX X X X Opposite shows a ‘cutting plane’ and a view showing the cut surfaces.
A cutting plane line is positioned to take a section through the cab, wheels and axle of a toy truck. The END ELEVATION is shown as Section XX. Parts A and B are not sectioned as air gaps they are air gaps. The axle is not sectioned as it has no information to reveal. The wheels are cross hatched in opposite directions to the main body. PLAN ELEVATION END ELEVATION SECTION XX
PLAN ELEVATION EXPLODED VIEW SECTION XX A cutting plane line is positioned to take a section through the lid and base of the salt shaker. The lid and base are cross hatched in opposite directions but with the same spacing Air gaps are not cross hatched. Hidden detail is never shown in a sectioned view.
Most of the toy train is made from the same kind of wood. The wheels are made from plastic. Cut surfaces are represented with cross hatching lines, evenly spaced, at 45º ELEVATION SECTION XX (Ready for Cross Hatching) Cutting plane lines indicate where a section is to be taken. Two pieces of the same material are represented with same spacing but opposite in direction. X X Letters are used to identify the cutting plane line.
ELEVATION SECTION XX The pictorial view shows how the axle is supported underneath. X X Air Gaps Air Gaps are not sectioned Nuts, bolts, washers, screws or shafts (axles) do not have to be shown in section. The example opposite shows how a section is cross hatched when one material is sandwiched between two pieces of another material. Using these rules SECTION XX would be cross hatched in the following way
X X SECTION XX Shelf Support When a cutting plane line passes support web through a thin support web along web its length then the web is not cross hatched in section. Webs are used to strengthen fitments like brackets etc.