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Sections PowerPoint Presentation

Sections

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Sections

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  1. Sections

  2. Sections Introduction 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

  3. Sections Introduction 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.

  4. Magic 45 Sections British Standards Rules 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. cutting plane line 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 X X When the section line ‘cuts’ through the centre of the donut it also passes through an ‘air gap’ as well as solid material. PLAN N.B. Air gaps are not cross hatched END ELEVATION SECTION XX

  5. Magic 45 Sections One Part Same Material Cutting Plane X Opposite shows a ‘cutting plane’ and a view showing the cut surfaces. 1. Draw the Magic 45º from the corner of the ELEVATION. X 2. Project the the breadth of the PLAN onto the Magic 45º then down to the ground line. X Pictorial Representation Showing Cut Surfaces 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. PLAN 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. Ground Line ELEVATION SECTION XX

  6. Sections Two Parts Same Material (example 1) 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 they are air gaps. PLAN A The axle is not sectioned as it has no information to reveal. B The wheels are cross hatched in opposite directions to the main body. END ELEVATIONSECTION XX ELEVATION

  7. Sections Two Parts Same Material (example 2) 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 PLAN EXPLODED VIEW Air gaps are not cross hatched. Hidden detail is never shown in a sectioned view. SECTION XX ELEVATION

  8. 45 Sections Revision of Rules on Sectioning 1 Cut surfaces are represented with cross hatching lines, evenly spaced, at 45º Most of the toy train is made from the same kind of wood. The wheels are made from plastic. 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. Letters are used to identify the cutting plane line. X X SECTION XX (Ready for Cross Hatching) ELEVATION

  9. Sections Revision of Rules on Sectioning 2 The example opposite shows how a section is cross hatched when one material is sandwiched between two pieces of another material. The pictorial view shows how the axle is supported underneath. Wood Metal Air Gaps are not sectioned Wood Nuts, bolts, washers, screws or shafts (axles) do not have to be shown in section. Using these rules SECTION XX would be cross hatched in the following way X X SECTION XX ELEVATION

  10. Sections A Very Special Rule When a cutting plane line passes through a thin support web along its length then the web is not cross hatched in section. Webs are used to strengthen fitments like brackets etc. Thin Support Web Shelf Support X X SECTION XX Storage Shelves