ASME Y14.3-2003 pdf download.MULTIVIEWAND SECTIONALVIEW DRAWINGS.
1.5 Orthographic View An orthographic view is the figure outlined upon the projection plane by means of the system of orthographic projection. Such a view shows the true shape ofa surface parallel to the projection plane (area ABCD with hole in Fig. 1). When an area is not parallel to the plane, the view of the area will be foreshortened (area BCEF in Fig. 1).
1.6 Projection Systems The two internationally recognized systems of projec- tion are third angle projection and first angle projection. Unless otherwise stated, this Standard features third angle projection.
1.6.1 Third Angle Projection. Third angle projection is the formation of an image or view upon a plane of projection placed between the object and the observer. Third angle projection is the accepted method used in the United States. See Fig. 2.
1.6.2 First Angle Projection. First angle projection places the object between the observer and the plane of projection. This method of projection used in some countries is herein described, in consideration of the need to interchange engineering drawings in an interna- tional market. See Fig. 3.
1.6.3 View Relationships. Note that the orthographic views of the object have the same configuration in both the first and third angle projections, but the placement of the views with respect to one another is different. The visibility of lines is always taken from the observer’s point of view. See Figs. 4 and 5.
1.6.4 Projection Symbols. The projection symbols shown in Figs. 2, 3, 4, and 5 are internationally recog- nized. Theymaybe used ondrawings to be interchanged internationally to identify the projection method used in preparing the drawing. See Fig. 8 for proportional sizes and allowable orientations.
1.7.2 Removed Views. Under certain conditions it may be impracticable to place a view in its normal aligned position. In this instance, viewing indicators are used to indicate from where the view was taken, and the view is removed to another location on the field of the drawing. See Fig. 9. Removed views are preferably shown on the same sheet from which the view has been taken. The removed view is identified using the view letters. The removed view may be drawn at the same scale as the view from which it is taken, or it may be drawn at a noted scale. It is also permissible to use a combination of numbers and letters for removed view identification.ASME Y14.3 pdf download.