CONSTRUCT SPACE TOLERANCE Type Tolerance

                

This command is used to define the tolerance for coordinate coincidence.

When a part is generated by the commands GEOMETRY COPY or GEOMETRY SWEEP the program checks if a point already exists within the current tolerance before generating a new point. Also, when merging parts using the MESHING MERGE command the tolerance is used to determine which nodes to merge on the interface between the two parts. Tolerance checking for SWEEP and COPY operations may be switched ON/OFF by the user, and both operations will be quicker if tolerance checking is off. Tolerance checking is always applied for MERGE operations.

It is possible to set the tolerance for a model in absolute terms or as relative to the size of the work-box.

Type = type of tolerance.

= ON if tolerance checking is required for SWEEP and COPY commands.

= OFF if tolerance checking is not required for SWEEP and COPY commands. This will make the sweep and copy operations quicker.

= ABSOLUTE if the `tolerance' is given as an absolute distance specified directly in the unit system of the model and is irrespective of the size of the work-box. A tolerance specified as absolute is unchanged if the work-box is subsequently changed.

= RELATIVE if the `tolerance' is given as a factor to be applied to the largest diagonal of the work-box. (See note 1).

Tolerance = real number specifying the new absolute tolerance or relative tolerance factor.

Notes:

1.

Relative tolerance
The CONSTRUCT SPACE TOLERANCE RELATIVE command allows the user to specify a relative tolerance as a factor of the largest diagonal of the work-box. If the largest diagonal of the work-box is = L, then the

absolute tolerance = relative tolerance * L

Note that the calculated absolute tolerance will automatically change as the size of the work-box is changed.

2.

Default tolerance value
The default tolerance for a new FEMGEN model is a relative tolerance of 0.001.

3.

Saving of the tolerance
The current tolerance is saved in the data base at the end of each working session with a model.

Examples:

1.

CONSTRUCT SPACE TOLERANCE ABSOLUTE .05

Defines the test distance as .05 units of the unit system of the model.

2.

CONSTRUCT SPACE TOLERANCE RELATIVE .005

Specifies that the test distance be calculated as a factor of .005 of the longest diagonal of the work-box.

See also the following commands

'CONSTRUCT SPACE WORK-BOX'
'UTILITY TABULATE GEOMETRY STATUS'