Orthographic Drawings Flashcards
Another name for orthographic drawing is?
Multi-view
What are the 6 principal orthographic views and is the proper alignment? What are the 3 most common shown views?
Top (above front)
Rear, left, front, right
Bottom (below front)
Front, top and right side are most common
What is another name for the basic lines used in drawings?
Alphabet of lines
How are object, hidden and centre lines shown and what are they used for?
Object lines are think, solid lines to show the visible edges, corners and surfaces of a part.
Hidden lines are used to show edges and surfaces that are not visible in a view. These lines are drawn as thin, evenly spaced dashes. Many times a surface or edge shown as an object line in one view will he shown as a hidden line in another.
Centre lines are thin, alternating long and short dashes that are generally used to show hole centres and centre positions of rounded features, such as an arc or radii. Arcs are sections of a circle, and radio are round corners or edges of a part. Centre lines can also show the symmetry of an object
What are dimension and extension lines? How are they drawn and what are they used for?
Dimension lines and extension lines are thin, solid lines that show the direction, length and limits of the dimensions of a part. Dimension lines are drawn with an arrowhead at both ends
Extension lines are drawn close to the edges or surface they limit. The length of extension lines is generally suited to the number of dimensions they limit
What are the 3 types of dimensions and what are they used for?
Size, location and notation
Size dimensions provide the overall sizes of an object and the size of individual details such as holes, slots and gussets. Size dimensions include length, width, diameter and angles
Location dimensions are necessary to place holes, gussets and other details on the object
Notation dimensions provide all the other information needed to fabricate the components. These include hole size, specifications and welding information
What are the methods of dimensioning?
Conventional
Baseline
Running
Notation
How does conventional and baseline dimensioning work?
The overall size of the component or assembly is indicated by vertical and horizontal dimension lines. Each size dimensions become a reference for the next. Conventional dimensions are used for welded fabrication ot tanks, hoppers, bases and frames when tolerance is not rigid.
Baseline is primarily used for machinery fabrication. One surface or edge of the component becomes a vertical reference and one becomes a horizontal reference. All size and location dimension originate on this line. The advantage is extreme accuracy and the disadvantage is drawing can become crowded and complex.
What us the fixed pitch or bevel ratio for dimension angles in imperial and metric?
Metric the ratio is 250
Imperial the ratio is 12
What us the fixed pitch or bevel ratio for dimension angles in imperial and metric?
Metric the ratio is 250
Imperial the ratio is 12
What angle are section lines drawn at?
45°
See page 42 for what different section lines mean
