T-FLEX Parametric CAD. Fundamentals. 2D Design

«Bottom-Up» Design
As a result, two intersecting construction lines will appear in the screen. Besides, a pair of external variables
will be created, x1 (x2, x3, ...) and y1 (y2, y3, ...). The parameters of the horizontal and the vertical
construction lines will be given by these variables. Thus, a fixing point is produced in the drawing. When
inserting this fragment in an assembly drawing, the system will ask you to specify the fixing point.
If necessary, a fixing point can be defined manually. To do this, just create manually two intersecting lines, a
vertical and a horizontal one, and assigne the reserved variable names to their parameters, x1 (x2, x3, ...) and
y1 (y2, y3, ...), respectively. The variables must be marked as external in this case.
Throughout the following description, the expression “Create first (second, …) fixing point” will imply
performing all steps of a fixing point creation described above.
Let's review most common techniques of creating fixing points of fragments and local coordinate systems in
a drawing.
Fragment with one fixing point without rotation provision
Create a fixing point. After that, create all construction lines relative to the vertical and horizontal
construction lines that define the fixing point. In the course of the drawing creation, do not use the lines of
types “vertical” and “horizontal”; rather, use the types “parallel” and “under angle”. If you follow those
rules, you'll get a drawing whose local coordinate system originates in the fixing point, and axes collinear
with the X-axis and Y-axis of a drawing in which the current fragment is being inserted.
Fragment with one fixing point with rotation provision
Create a fixing point. Then, create a construction line passing through the node
of the fixing point, at an angle to the horizontal line. Assign the slant angle of
the line the variable “al”. When creating the variable, mark it as external and
enter value other than 0 (entering “0” will make the lines coincide with the
horizontal line on the drawing, complicating further constructions). The variable
“al” will be an external variable of the drawing. Upon inserting the drawing as
a fragment, the system will be asking for the value of the variable “al”.
The construction line passing through the node at an angle to the horizontal line
defines the X-axis of the new local coordinate system in this drawing. To create
the Y-axis, make a construction line passing through the node and orthogonal to
the slanted construction line that is passing at the specified angle to the
horizontal line.
The slanted line and the line perpendicular to it define a new local coordinate
system in the drawing. All further constructions must be based on these lines.
As a result, a parametric fragment will be built with one fixing point and the
variable “al”, that will be defining the slant angle of the fragment coordinate system with respect to the
coordinates of the assembly drawing.
To make further constructions with respect to the new coordinate system easy, we recommend doing the
following steps. Set the level value equal to “-1” for the vertical and horizontal lines passing through the
fixing point. The lines will disappear from display as the construction lines visibility levels are defined by
the range from 0 to 127 in the command “SH: Set Levels”, while these lines are assigned the level -1 and
do not belong in the range. After that, call the command “ST: Set Model Status”, switch to the tab
“Screen” and select the value “Visible only” in the parameter “Element selection”. By doing so, you set
the drawing into the mode in which the elements will not be selectable that are not shown on the drawing.
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