You will now be able to dynamically drag the dimensions to the required position (drag the dimension to the right-hand side of the component and confirm using the left hand mouse button).
We have now completed the dimensioning of this drawing by us-ing the dimensionus-ing tools that are available to us (see Page 2).
Step 5 - Creating ‘Datasets’
The ‘constraint manager’ is an intelligent design tool. It will an-alyse a 'group' of geometrical elements, (which we call a data-set), determine the associativity between these elements, and then when one element is changed in some way, it will change all the other elements that form some association with it.
As a simple example; if a triangle is created, and one of the seg-ments moved, then the constraint manager will extend the other lines to the point of intersection, maintain the angle at the apex of the triangle, and update the associated dimensions.
One important fact to note is that the process of creating the ele-ments (its history) is completely irrelevant. It does not matter who defined the geometry, or indeed where it was created. If ge-ometry is imported via IGES or DXF it can still be assigned to a data set, its geometrical associativity analysed, and then changed so that intersection points are maintained. Tangent elements
re-For more information
Y Axis X Axis
Z Axis
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Each ’set’of connected elements is referred to as a data set. There may be up to 255 data sets in a file, but an element cannot belong to more than one data set simultaneously. As many designs have common features, a data set can be saved (rather like a symbol), and subsequently recalled into the current workfile. When a workfile is saved through the standard file options however, the data set information is not saved with it.
All data set elements must lie on the same workplane. In the un-likely event that the number of allowable data sets is exce eded it is necessary to save the work file, and any required data sets, and create a new file.
A dataset contains a database, which defines the connectivity be-tween its elements. It does not contain the data that describes the physical spatial location of its elements.
The dataset option contains the following functions:
Create Dataset
This function creates a dataset. The elements are selected using the standard techniques including enclosing the elements in a box, picking etc. If an element already belongs to an existing data set it is de-selected, and a warning will be given.
When the selection is confirmed the dataset is analysed (see also Set Dataset Defaults). The following types of element may be as-signed to a dataset: Segments, circles, arcs and dimensions.
Move Element
This function allows a segment, circle or arc to be moved. For segments the ’moved’element is parallel to the original element and passes through the picked point. For circles and arcs the cen-tre is effectively being moved.
For more information press the [F1] key on your keyboard.
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Change Length/Radius
This will change the length of a segment or the radius of a circle or arc. For segments it is possible to move the start, or end, or both ends of the segment.
For circles or arcs where there is tangency, it is necessary to se-lect either to move the circle centre (thus maintaining the relative position of the tangent elements) or to maintain the centre.
Change El-El Distance
This will change the distance between two circle or arc centres or between two parallel segments.
For parallel segments either or both segments may be moved.
For circle/arc distances, in addition to the selection of certain el-ement(s) to be moved, the distance may be defined as horizontal, or vertical or (provided the element centres do not lie on one of the workplane axes) centre-centre distance.
Change Dimension
If the data set contains dimensions then the movement of any el-ement will also update the associated dimension. Sometimes it may be easier to change the dimension directly. The options available depend upon the type of dimension.
The location of dimensions needs to change after the elements referenced have been moved. However the ’best’ positions are very much in the eye of the designer. There is no analytical best position. Therefore be prepared to move them again yourself.
(i) Single Dimension - A linear dimension can be modified provided it refers to the distance between two circle cen-tres, or two parallel lines.
For more information
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As with ‘Change El-El Distance’ a number of options are available as to which element is to be changed.
(ii) Circle/Arc Dimensions - All circle/arc dimensions can be modified.
(iii) Angular Dimensions - Angular dimensions can be changed by moving the first, second or both elements.
Dataset Defaults
When a dataset is selected, it is analysed using the constraints defined in the parameter list. These parameters are:
Shared Points
A shared point is a common point between two elements. If a segment ends at one point and another starts at the same point, then this is a shared point. If one element is subsequently moved then any other that shares a point on that element must be moved.
Intersection Points
An intersection point is where one element starts or terminates at its intersection position with another. If the intersecting element is moved, then its 'length' must be recalculated to produce anoth-er intanoth-ersection point with the intanoth-ersected element.
If the two elements are segments then provided the two lines are not parallel, an intersection point will always exist (it need not lie within the extents of the intersected element). If either ele-ment is an arc or a circle then this imposes a physical restriction on the amount by which either element can be moved.
NOTE
The segment cannot move beyond this line (see Figure 3.97) as
For more information press the [F1] key on your keyboard.