T-FLEX Parametric CAD. Fundamentals. 2D Design

Fundamentals. Two-Dimensional Design
710
First, define the driving variables for the rest of dimensions, whose values need to be defined when
assembling the part. In this example, those are the diameter, the length and the implementation (see below).
If a variable has a set of standard values, it is helpful to create the predefined list of values for convenient
and quick input. The list of values can be created based on an existing field in the database. Upon creating a
variable, it is a good practice to put a description in the comment field, so that another person can easily
decide on what data to input, when working with this document.
Next, we need to create variables that keep track of the database record number from which the values are
taken. Such variable value can be read by calling the function rec or frec. For the functions description, refer
to the chapter “Databases”. In this example, we need two such variables: one (the variable n) for accessing
the values dependent on the bolt diameter from the respective database, and the other (the variable nl) for
maintaining the value of the length. The challenge here is that the second variable should be assigned an
appropriate record number across different databases (depending on the diameter). Besides, one should keep
in mind, that the input length might not be always correct, as the designer of the part could enter a
nonstandard bolt length. Therefore, the value of the variable nl can be described by the expression: d==6 ?
frec(6.l,l) : (d==8 ? frec(l8.l,l) : d==… ), that means, if the variable d (diameter) is equal to 6, then do the
search for the record number in the database number 6, otherwise, if the variable d is equal to 8 - then do the
search for the record number in the database named l8, and so on over all databases.
Next, create the rest of the variables. Their values are accessed by calling the function val based on the value
of the variable that keeps the record number of the database (those are - n and nl). The value of the bolt
length (ll) will be defined by the expression: d==6 ? val(nl,l6) : (d==8 ? val(l8.l,l) :d==… ). The meaning
of this expression is similar to that of the variable nl described above.
The bolt has several implementations. The drawing should adjust, depending on the implementation. This
can be fulfilled by setting, when necessary, the level of certain drawing elements below the displayable
threshold. We need to create special variables for this purpose (separate for each implementation). By
default, the displayable elements have level from 0 to 127. If the level of an element is below zero, it is not
displayed. Consider, for example, the variable imp25 that defines the level of the elements visible only in the
implementations number two and five. It is equal to 0 when the implementation (defined by the string
variable $imp) is equal to “2 - with pin hole” or “5 - with pin hole and groove”, and is equal to -10 in all
other cases: $imp=="2 - with pin hole"||$imp=="5 - with pin hole and groove"?0:-10.