1.3 Drawing Standards

Technical Drawing Standards

    Borderline - a continuous rectangle near the edge of the page that encloses the drawing space and separates it from the margins.  No parts of the drawing may touch or cross the borderline.  Borderlines should be the darkest and thickest lines on the page.  

    Title Block - A rectangular area just inside the borderline along one side or in one corner of the drawing space.  The title block provides on place on the page to find all of the important information about the drawing, where, when, and by whom was it made.  When creating a set of drawings, the title block will be consistent on all sheets and will state how many pages there are and which page this one is.  

    Lettering -  The accepted way to put text on a technical drawing is called "lettering".  Simply put, this mean that you are writing everything in all capital letters.   This is to make it easier to read.  The only exception would be if you are including an extensive note or paragraph along with the drawing.  In that situation, it may be more appropriate to use standard upper and lower case letter in that one location.

        Construction Lines - These lines show the reference for the objects being drawn but not part of the object.  This lines can show how features line-up, are symmetrical, or help locate where views will be place on the page.  These are very thin and light lines that should be erased in final technical drawings.

        Object Lines - These lines show the visible edges of the objects being describe in the drawing.  Object lines are dark and solid (no gaps or spaces) so that they are the lines that stand out the most on the page.  Only the borderlines should be wider then the object lines.

        Hidden Lines - These lines show the edges of the object that are not visible in that view.  Hidden lines are dashed lines (short line, space, short line) that are lighter and thinner then object lines.  The length and spacing of the dashes should be very consistent. 

        Center Lines - These lines are used to make the location of the centers of circles, arcs, or lines of symmetry.  Because these lines do not represent edges of the object, they are lighter then object lines and thinner than hidden lines.  Center lines are made up of a series of long line, space, short line, space, and a long line.  When marking the center of a circle or arc, the short lines of a vertical and a horizontal center line form a plus sign (+) at the exact center.  When showing a long line of symmetry, the center line may repeat with a repeating pattern of long and short lines.

        Dimension Lines - These lines are not part of the object but are added to the drawing to make it easier to define the size and location of object features.  Dimension lines are solid and as thin and light as center lines, but always end with arrows (or some other symbol) at each end.  The dimension line will be the same length as the feature of the object it is stating the length of.  Near the middle of the dimension line will be written the stated value for the length.  This could be written next to the dimension line or the writing might be in line with the dimension line (breaking it into two parts).  Whenever possible dimension lines should be placed outside of the object (not inside or over the object) and when possible, avoid the dimension line touching the edge of the object.

      Extension Lines - These lines are not part of the object but  are added to the drawing to make it more clear which feature of the object is being dimensioned.  Extension lines are solid lines that are as thin and light  as center lines.  A standard extension line would start just beyond the edge of the object and extend just a little past the end of the corresponding dimension line that is pointing at it.  Sometimes an extension line will be a continuation of a center line.  Whenever possible, avoid having extension lines that extend into (inside or over) the view of the object.

        Leader Lines - These lines are not part of the object but are added to the drawing to connect a notation to a specific feature of the object.  Leader lines are solid lines that are as thin and light as center lines.  One end of the leader line has an arrow that points to the feature and the notation about the feature will  be at the other end.  Leader lines are often used to dimension the diameter of circles and the radius of arcs.  Details about the shape and depth of holes can also be stated at the end of leader lines.