Radial Dimensions

A Radial Dimension (RDIM) is a form of linear dimension that may be used to draw radius and diameter dimensions of circular elements. A Radial Dimension does not own Dimension Point elements, but is defined by a database reference to an element type (the one to be dimensioned) and an attribute taken from that element which defines whether a diameter or a radius is to be drawn. An example is DIAM of a CYLI (the diameter of a cylinder) or FRAD of a PAVE (fillet radius of a Panel Vertex).Figure 12:21 below shows the principal features of an RDIM and Figure 12:22 below shows examples of types of RDIM.

A Pitch Circle Dimension (PDIM) is another form of radial dimension - see Pitch Circle Dimensions.

Figure 12:21. Radial Dimension - Principal Features

Figure 12:22. Radial Dimensions - Examples

Radial Dimensions have a dimension centre, defined by the DDNM (Design Data Name) attribute. This is an attribute of the RDIM itself, and is normally defined by the origin of the element dimensioned. (See Radial Dimensions for exceptions to this.) This could be (for example) the origin of a CYLI or of a (filleted) PAVE (Panel Vertex).

The other principal attribute of an RDIM is the dimension attribute key, AKEY. This is a word attribute that stores the code of a dimensional attribute of the Design element type that is to be dimensioned. The default value of AKEY is DIAM.

The following table shows which attributes of which Design element types may be dimensioned using an RDIM.

The command:

Q AKEYLIST

(at a Design element) returns the list of possible AKEY settings.

Most of the AKEY settings allowed above are genuine database attributes; however, the DIAM keyword has different meanings at different elements. For some Design elements it is a genuine attribute, for others it is derived:

• DIAM is a genuine attribute of Dishes (DISH, NDIS) and all Cylinders (CYLI, NCYL, SLCY, NSLC).

• For a Torus (RTOR, NRTO, CTOR, NCTO), DIAM give the centreline diameter of the element - that means, twice the average of RINS and ROUT.

• For Snouts (SNOU, NSNO) and Cones (CONE, NCON), DIAM is taken to be DBOT, the bottom diameter.

• For Structural Vertices (VERT, PAVE, SEVE), DIAM is taken to be twice the fillet radius (FRAD) if it is set. The origin is normally the position of p9 of the vertex.

The centre of a Radial Dimension is normally defined by the origin of the element dimensioned, except for the following AKEY settings:

• For DTOP and DBOT, the dimension centre will be the centre of the appropriate end of the primitive. This also applies to DIAM for Snouts and Cones.

• For FRAD, the centre of the fillet radius is defined by one of the many p-points of the Vertex (p8 or p9). This also applies to DIAM if the FRAD value is being used.

• The RADI attribute of a dish (DISH, NDIS) is the knuckle radius. The CRAD attribute of a dish is the cap radius. The centres of these radii are derived. Both these AKEY settings are only sensible for a sideways view of a tori-spherical dish.