Engineering Graphics 1504Lecture 2 – Orthographic Sketches Objectives • Recap of Orthographic Projections • Lettering and title blocks • In-class assignment
Recap: Lines Strong contrast between drawing lines and construction lines • Visible lines indicate all visible edges. • Hidden lines show surface, edge, or corner hidden from view • Centerlines show holes and symmetric features • Cutting plane used to designate where cutting plane takes place • Extension & dimension lines used when dimensioning • Break lines used to shorten view of a long part • Section lines used to indicate the surface in a section view
Visible Line Functions “LIMITS” “EDGES”
Hidden Line Conventions • evenly spaced dashes • spaces 1/2 of dash length • dashes commonly 1/8” long
Centerline Conventions • to show circle/arc center or axis of symmetry • long lines separated by dash and two gaps • dashes commonly 1/8” long
Tangent Surfaces When a curved surface is tangent to a plane NO LINE IS SHOWN
Producing a Multiview Sketch • Select Front View • Align View Bounding Boxes • Sketch Features • True Shapes Remain • Project Between Views • Label Vertices if Needed
Select Front View • Universally Used -- Clock Face • Shows Most Characteristic Shape -- the “U” shape of a horse shoe. • Generates Fewest Number of Hidden Lines for Entire Drawing
Creating the Orthographic Projection Sketch • Front View • Right Side View • Top View
Align View Bounding Boxes WIDTH DEPTH TOP DEPTH WIDTH Miter line at 45° HEIGHT HEIGHT FRONT RIGHT
Sketch Features – View Projection TOP Miter line at 45° Note: see figure 1.29 in text FRONT RIGHT
Standard Letters (ASME Y14.2M-1992) Vertical Gothic Style – All Capitals A Lettering Template These suggested lettering strokes may be helpful.
Lettering Guidelines • Letter size should be at least 3mm high for clarity and reproducibility • Draw a construction line to help you judge lettering height. • Decimal points must be clearly visible, solid, and in-line with bottom of text • To be aligned with the bottom of the page (preferred) or with the right side of the page.
Spacing & Fractions Don’t use equal spacing between letters Instead, try to balance the area between letters. The space between words should be equal to letter height. The space between lines of text should be at least half the height of a letter and at most equal to the letter height.
Lettering Example • Extremely light horizontal lines regulate letter height • Guidelines are not removed • Vertical lines may be used to keep letters vertical (not used to space the letters)
Lettering Cont. • Note: strict adherence to these guidelines is not necessary, but … • Make sure that all letters are in upper case, and construction lines are visible
Title Block • Vary in layout • In this course must include • Name • Title or description • Scale and units • Drawn by: • Date: • Session identifier (eg. Wed.)
Class Assignment • Using your workbook, complete questions 9,11,13,15 • Include a title block on the first page