Changing Linear to Ordinate Dimensions

Assuming a plate created with holes shown. The holes were created with the mirror option and using constraints, although any method of creating the holes is acceptable as long as the holes reference the center of the part.

In Drawing mode, select Modify – Dim Params – Dim Type – Ordinate Dim – Create Base. Select the 1.5 horizontal dimensions in the upper right quadrant.

When prompted to select a Base line, select the edge view of RIGHT datum plane.

Notice that the dimension changed from a linear to an ordinate, with .000 being located at the edge of the datum.

Lin to Ord is currently selected for you in the menu tree. Continue to pick on the horizontal dimensions to convert.

The horizontal 10.00 cannot be converted, as it doesn’t reference the datum.

Reselect Create Base from the menu, select the 1.00 vertical dimension, set the Base Line to TOP datum plane and pick on the other 1.00 dimension to convert to ordinate.

After Clean Dims, Move and Clip operations have been performed to clean up the drawing.

To add ordinate dimensions to define the overall size of the plate, turn the datum planes back on and create the two 5.00 horizontal dimensions and the two 3.00 vertical dimensions as driven dimensions.

Turn these into ordinate dimensions as was done earlier except that instead of Create Base, use Set Base and select the .000 dimension to define the base for converting the linear dimensions. Only ONE base can be active at any point in time.

Jogs can be created by selecting Make Jog under the main Detail menu, or by adding the jog in when converting the linear dimension to an ordinate dimension. If doing the latter, select One Jog from the lowest menu before selecting the dimension to convert. After selecting the dimension, pick on the witness line where you want the jog to start, and next select where the jog should be located. The overall 5.00 dimensions were jogged below. Move will allow you to relocate the text after the jog has been created.

When dimensions are converted to a different type (ordinate or linear), this is reflected in the model.

If the holes were created with a pattern table, some of the dimensions would appear as linear and some as ordinate in the model. Why?

Answer: Not all dimensions were changed to ordinate on the drawing. There were a lot of duplicate dimensions that were erased before the conversion from linear to ordinate was performed. Each hole has two locating dimensions associated with it. Ten of the twelve 1.00 dimensions locating the hole from the center of the plate were erased from the drawing before converting the dimensions to ordinate.