Axonometric drawings BDU 10303

2D Drawing Types Pictoral drawing Multiview drawing Drawing that show 3 principal faces of the object in one view Example: Axonometric drawings Isometric Dimetric Trimetric Oblique drawings Multiview drawing Shows only two dimensions in each view Orthographic drawing

Isometric drawing Isometric drawing present the pictorial view of an object. More easy to understand than orthographic projection. Is an application of the orthographic projection.

Conventional Isometric Projection Note that there are three isometric axes. These are inclined at 120° to each other. One axis is vertical and the other two axes are therefore at 30° to the horizontal. The faces of the shaped block are all at 90° to each other. The lines in the isometric drawing are parallel to the isometric axes. For example... If the lines are not parallel to any of the isometric axes, they are no longer true lengths.

Isometric projection Isometric projection is a true representation of the isometric view of an object Isometric view is created by rotating the object 45 deg about vertical axes and tilting forward about 16’.

Selection of Isometric Axes Main purpose of isometric view is to provide pictorial view which reveals as much detail as possible. Selection of principal edges is important

Isometric projection : scale The tilt causes the edge & planes to become foreshortened. The projected length is approximately 80% of the true length.

Isometric projection & drawing To avoid difficulty in determining foreshortened length, we can draw isometric projection directly by using true length! However the drawing will be larger than the actual size (22.5% larger) Isometric projection Isometric drawing

Iso-circles and arcs Isometric circles or iso-circle cannot be simply drawn using compass. Any iso-circle may lie on either top plane, left (front) plane or right (profile) plane. Iso-circle looks slightly oval and skewed.

Drawing Iso-circles Draw centre lines, vertical & 30deg to left. Draw (construction line) “square box”. The centre lines should divide each side by half. Draw straight lines; 1-2 & 1-3 and 2-5 & 2-6. Point 7 is the intersection between line 1-2 & 4-5, and similarly point 8, 1-3 & 4-6 on the other side. Set your compass to the distance 7-2, draw an arc with centre at point 7, from point 2 to point 5. Do the same on the other side. Set your compass to the distance 1-2, draw an arc with centre (1), from 2 to 3.

Irregular curves Irregular curves in isometric are produced by transferring the coordinates from orthogonal view. A fixed distance is set, A, and the distance in B direction are obtained. These values are then transferred to the isometric view.

Producing Isometric drawing Start to draw when you are able to visualize the objects. Start with construction lines: Draw the iso-box Filled the box with lines Darken the lines, arcs and circles related to the object.

Axonometric Projection Steps in Making an Isometric Drawing Draw the enclosing box using the overall dimensions of the object with construction lines. Block in the various shapes and details using construction lines. Darken in all final lines.

Assignment 3 Draw, full size, an isometric projection of the component shown in following figure looking in the direction of the arrow A