Civil Engineering Reference
In-Depth Information
FIGURE 2.4
The dimension and tolerance matrix after operation 1.
Step 3. Operation 2
The upper half of the matrix divided by the diagonal is inspected cell by cell from
top to bottom. The aim is to determine the location of the reference cell and the parent cell. The
value of the empty cell of a dimension or tolerance matrix is the absolute difference between or
sum of the value of the reference and the value of the parent cell. If a cell is empty then the
leftmost element of that row is the reference element, the column face of the reference element
and the column face of the empty cell are noted. The parent cell is located as follows:
Column of parent cell
Column of the cell of the empty element
Row of the parent cell
Column of the cell of the reference element
Using the reference surfaces, the dimensions and tolerances are derived as follows:
Bc
MOD (BG
CG)
where BG is the reference surface in the dimension matrix,
CG
where BG is the reference surface in the tolerance matrix.
Bc
BG
