─ 1.1. Geometry creation

There are some important elements that should be taken into account for the geometric modelling:

Units: It is recommended to work with the Units that fit the most to the dimensions of the geometry, as some parameters are automatically set-up. The following functions are especially sensitive to the working Units.

Mouse functions: such as zoom and selection functions. If any difficulty is found for these purposes, select the approximated elements on the desired area or from the Tree, click on Reset View button and the click on Zoom Selected button. Then, the camera functions are centered on the selection to improve the mouse functions near this region.
Boolean operations: such as split or projection commands. It is recommended that the Units are similar to the smaller elements involved on boolean operations, as the accuracy may be improved.
Meshing process: advanced meshing parameters such as the edges detection factors are predefined to the working Units.

Reference Plane: This utility is useful to place and orientate correctly any geometric element. If the reference plane local coordinates are enabled, every new command will generate the new object according to the reference system.

For starting with this example, the default Units and Reference Plane are valid.

Next, click on Geometry – Parameters – Define Parameters menu to create the list of parameters that are required for the geometry creation. The geometrical parameters are listed in next table.

Parameter	Description	Value
Height	Height of the box and the two cylinders	{2.0}
BoxCenterX	X coordinate of base center for the box	{0.0}
BoxCenterY	Y coordinate of base center for the box	{0.0}
BoxWidth	Width of the box (X size)	{0.5}
BoxDepth	Depth of the box (Y size)	{1.5}
t	Parametric auxiliary variable	[0 0.9] 5
R1	Parametric radius of left cylinder	0.15*(1+t/5.0)
R2	Parametric radius of right cylinder	0.25*(1+t/8.0)
HoleEdge	Size edge of the box hole	BoxDepth/4.0
HoleCenterY	Y coordinate of the center for the hole	t*BoxDepth
HoleCenterZ	Z coordinate of the center for the hole	{1.1}

Geometrical parameters defined

Use the previously defined commands to create the geometry with the existing primitives. Two cylinders and two boxes must be created. Then, the booleanDifference between the two boxes is required. The geometry creation is detailed in the table and figure above.

Command	Parameters	Values
box	X corner base	BoxCenterX-BoxWidth/2.0
	Y corner base	BoxCenterY-BoxDepth/2.0
	Z corner base	0.0
	Width	BoxWidth
	Depth	BoxDepth
	Height	Height
cylinder	X center	0.0
	Y center	-BoxDepth
	Z center	0.0
	Radius	R1
	Height	Height
cylinder	X center	0.0
	Y center	BoxDepth
	Z center	0.0
	Radius	R2
	Height	Height
box	Xcorner base	BoxCenterX-BoxWidth/2.0
	Y corner base	(BoxCenterY-BoxDepth/2.0)+HoleCenterY-(HoleEdge/2.0)
	Z corner base	HoleCenterZ
	Width	BoxWidth
	Depth	HoleEdge
	Height	HoleEdge
booleanDifference	Object A	Box 1
booleanDifference	Object B	Box 2

Commands parameters description

gtd-coupling_console

Geometry creation by using console commands