Parameters and formulas
Every numeric field in the program takes an expression, not just a number: 40/2, w*2,
len+5, sin(30)*10, pi*d.
h is computed from w, and d from w and wall. Change one number and all of them follow.
Global parameters
The “ƒx Parameters” window in the top bar holds the named values of the project: a name, an
expression, the computed value. A parameter can refer to another one — d = w/2.
That name then works in any field: in a sketch dimension, in an extrusion height, in a fillet radius, in an array spacing, in a joint angle.
What it is for
One number the whole part depends on must live in one place. Sheet thickness, fastener pitch, shaft diameter — if they are retyped into twenty fields, one day you will fix nineteen of them.
A practical habit: create the parameters before drawing and type their names straight away. That is cheaper than coming back and replacing numbers later.
Named sketch dimensions
A sketch dimension can be named and then becomes available as a parameter. That is how a skeleton is built: the main sketch sets the overall sizes, and the parts take their dimensions from its named ones.
What can go wrong
A mistake in a formula does not break the document: the field keeps the previous value and says what
is wrong. Circular references (a = b, b = a) are not computed — the program says that too.
See also
- Sketch dimensions — where named dimensions come from.
- Documents and templates — how to carry a set of parameters into a new project.