Alibre Options: Apply Linear Dimensions to Circular Figures

14 Mar, 2005 By: Michael Todd Cadalyst

Alibre Design's Slot Dimension Options dialog box makes the job easy

As the Alibre Assistant, I'm often asked: "I need to apply dimensions to more complex figures like slots -- which tool should I use for this?"

In Alibre Design, applying dimensions to any single circular figure or arc is simple. Just use the Dimension tool. But how do you apply a dimension to a pair of circular arcs or a circular arc and a line? Use the same Dimension tool, but make sure the last figure selected is a circular arc to take advantage of the capabilities found in the Slot Dimension Options dialog box. The Slot Dimension Options dialog box automatically displays the dimension options available based on the selected geometry.

This is especially useful when dimensioning slots or circular objects such as fillets. This dialog box is available in both the part workspace and drawings. If the dimension information you need is not already in a drawing, quickly and easily add it with the help of the Slot Dimension Options dialog box.

Versatile Options
The most useful aspect of the Slot Dimension Options dialog box isn't necessarily for a slot. You can also use this dialog box to define the tangent outside, tangent inside or center of holes, and from a hole to an edge. When used with any combination of circular arcs, circles and lines or nodes, the Alibre Design Slot Dimension Options dialog box is a powerful feature that helps designers and engineers convey the correct information to the fabricator.

For this example, we will use an existing drawing. You may use one of your own, or download the sample drawing used in this tip. The drawing contains slots and holes, both of which can be dimensioned with the Slot Dimension Options dialog box.

To use one of your drawings, simply open it in Alibre Design. To use the sample drawing, right-click this link and select Save Target As to download the sample drawing and associated part. Extract both the part and drawing to the same folder; then open the drawing in Alibre Design.

Figure 1. The part in this drawing contains both slots and holes.

  • Select the dimension tool. Depending on which geometry is selected, you may now insert different types of dimensions including linear, angular and slot.

Figure 2. A detail of the parts of the drawing to select.

  • Select the line edge; then the circular arc on the slot as shown (figure 2). The Slot Dimension Options dialog box shows that there are three acceptable types of dimension that can be applied: Line To Center, Line To Outside and Line To Inside.

Figure 2a. The dialog box as it appears when the drawing elements in figure 2 are selected.

  • Select Line To Outside; then click OK.
  • Place the dimension as shown (figure 3).
Notes: To bypass the Slot Dimension Options dialog box, make sure that your first selection is circular, and the last is a noncircular figure. In the Slot Dimension Options dialog box, the numbers in the Slot Dimension Style pull-down menu correspond to the numbers in the diagram. The diagram shows what dimension to expect when the numbered option is used.

Figure 3. Select the circular objects as shown to see applicable dimension options.

  • Select two circular objects as shown (figure 3). The number of dimension options available in the Slot Dimension Options dialog box increases (figure 3a). Note that there are now 13 possible dimension combinations (numbered 0-12). The diagram shows the corresponding dimension and option number as a result of the selection, so you can see what the dimension will represent on the drawing.

Figure 3a. Thirteen dimension styles are available; numbered 0-12.

  • Select Outside to Inside; then click OK.
  • Place the dimension as desired.

Figure 4. A detail view of holes in the drawing.

  • Select two holes as shown (figure 4). As mentioned previously, the Slot Dimension Options dialog box isn't just for slots. It can be used for holes of any type, and for a hole and an edge.
  • Select Center to Center; then click OK.
  • Place the dimension as shown (figure 5).

Figure 5. As specified in the Slot Dimension Options dialog box, the dimension appears as shown.

The Center to Center dimension is the standard dimension practice; however, Alibre Design gives you the ability select other options as fits your business solution.

Next month we'll look creating a customized Bill of Materials for your assembly drawings. Until then, look for me as the Alibre Assistant online in Alibre Design.

About the Author: Michael Todd