MonoGRAF. Draughting program

MonoGRAF dimensioning

Dimension types

In many applications, a precise drawing plotted to scale is not sufficient to convey the desired information; annotations must be added showing the lengths of objects or the distance or angles between objects. Dimensioning is the process of adding these annotations to a drawing. The term dimensioning also refers to the annotations themselves. MonoGRAF provides four basic types of dimensioning: linear, angular, diameter, and radius. You can draw dimensions "by hand", using the commands from CALC menu to obtain the relevant information and then draw the necessary lines, arcs, and text. However, MonoGRAF's dimensioning feature makes this process much simpler.

Basic terms

The basic terms used in this chapter are the following:

  • dimension line - this is a line with arrows at each end, drawn at the angle at which the dimension has been measured. The dimension text is situated along this line. Usually, the dimension line is inside the measured area. Sometimes, however, it does not fit. In such cases, two short lines are drawn outside the measured area, with arrows pointing inward. For angular dimensioning, the dimension line is actually an arc. For linear dimensioning, you can select "hatch length" to be drawn rather than arrows. Hatch length represents short lines drawn through the points where the dimension line meets the extension lines, at 45 degrees with respect to the dimension line;

  • extension lines - if the dimension line is drawn outside the object which is being measured, straight extension lines are drawn from the object, perpendicular to the dimension line. Extension lines are used only in linear and angular dimensioning. Because they are sometimes superfluous, means are provided to suppress one or both of them;

  • dimension text - this is a text string that usually specifies the actual measurement. You can use the measurement computed automatically by MonoGRAF, supply your own text, or suppress the text entirely. If you use the default text, you can instruct MonoGRAF to append plus/minus tolerances to it automatically (see Tolerances below);

  • tolerances - dimension tolerances are plus/minus amounts that MonoGRAF can append to the dimension text it generates automatically. You specify the plus and minus amounts; they may be equal or different. If the plus and minus tolerances are equal, MonoGRAF draws them with a "plus/minus" symbol. If they differ, the tolerances are drawn one above the other;

  • leader line - for some dimensioning or any annotations, the text may not fit comfortably next to the object it describes. In such cases, it is customary to place the text nearby and draw a "leader" line from the text to the object. For instance, when diameter or radius dimensioning is desired, but the arc or circle is too small for the dimension text to fit inside, a leader can be drawn from the text to the arc or circle;

  • center mark/line - a "center mark" is a small cross marking the center of a circle or arc. "Center lines" are broken lines crossing at the center and intersecting the circumference of the circle or arc at its quadrant points;

  • dimension parameters - the manner in which dimensions are drawn is controlled by a set of "dimensioning parameters". You can change their values to meet the requirements of a particular dimensioning situation. Some of the parameters are simply "on/off" switches, whereas others hold numeric values. The dimension parameters can be used to define (or change) such elements, as hatch length, text high, length of the extension line and arrangement of its parts in accordance with dimension line etc.

The dimension line, extension lines, arrows, leaders, and dimension text are drawn as separate entities on the current layer. Thus, after a dimension has been drawn, you can change the placement or content of the text, etc.

Dimensioning commands

The "dimension" menu includes the following elements:

    Dimensioning submenu

The dimensioning commands can be grouped into four categories:

1. Linear dimensioning commands:
  • horizontal
  • vertical
  • parallel
  • directed
  • baseline
  • chain line
2. Angular dimensioning commands:
  • angular
3. Diameter and radius dimensioning commands:
  • diameter
  • radius
4. Additional dimensioning commands:
  • center
  • leader

5. Dimension parameters

A complex drawing with all dimensioning types is shown in the following figure.

All dimensioning types

All dimensioning types

Dimension parameters

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