Creating a Parametric Part

This section explains how to create a parametric part from within TurboCAD.

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1. In this example, Auto Constraints is turned on. This is so that dimensions can be used as parameters, and so that geometric relationships between objects will be maintained when parameters are changed.   ----

Note: For details on constraining objects, see Auto Constraint.----

1. Create a polyline using two identical linear segments and two tangent arc segments.
2. Create two circles concentric with the polyline arcs. The circles can be different sizes now, but in the eventual parametric part, the circles will be identical.
3. Apply Concentric constraints so that the circles will remain concentric with the polyline arcs.
4. Add a Linear Dimension and a Radial Dimension to measure the polyline.
5. Activate Simple Extrude, and make sure Use Compound Profile is active. Select the polyline, then press Shift and select two circles. Click to define the height, or enter an exact value.

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1. Next, highlight the other Circle. The other circle is now highlighted on the model.
2. Right-click on the Radius field.
3. Enter the parameter name "H2."
4. For the next parameter, highlight the Radial Dimension. The dimension of the polyline arc is now highlighted.
5. The Value field of this dimension is found under "Constraints." Right-click on this field.
6. Name this parameter "R."
7. Next is the Linear Dimension.
8. This value is also found under "Constraints." Name its parameter "W."
9. The last parameter is the depth of the part. Highlight "Simple Extrude."
10. This parameter is called "Height" and is found under "Simple Extrude." Right-click on this field.
11. Name this last parameter "D."
12. Now that all five parameters are defined, select Finish from the local menu or Inspector Bar.   ----

Note: There are other options in the local menu and Inspector Bar. Relocate Reference Point enables you to define the point by which the part will be inserted. For circular parts, Set Assembly Axis can be used to set an axis for assembly using Assemble by Axis (see Assemble by Axis).----

Step 3- Defining Relationships between Parameters

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1. The Parametric Part window is now open, in which you can define relationships between the parameters you've defined. First, enter a name for the part.
2. The eventual part will be defined by only three parameters: the hole radius, distance between hole centers, and depth. All other parameters will be functions of these three.
3. The names of the parameters currently listed don't tell the user exactly what they are for, so we can add parameters with more obvious names. To do this, right-click on the first parameter on the list, and select Insert Parameter.
4. Name this parameter "HoleRad."
5. "HoleRad" is now first parameter on the list. Under "Value," enter the default radius that will be used when you first insert the part.
6. Under "Type," specify "Linear."
7. Create another parameter for the center-to-center distance between the holes. This parameter can be named "CenToCen". Specify an initial "Value" and "Type."
8. Under "Value" next to "H1," replace the number with "HoleRad." Do the same for "H2."
9. Define"R" as twice the hole radius.
10. Set "W" as equal to "CenToCen."
11. Now the three controling parameters needed for the part are defined. They are "HoleRad," "CenToCen," and "D." Click Finish to close the Parametric Part window.

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With the edit tool active you can save all of the Parametric parts in a *.SLW file.

You can also Load Parametric parts from an *.TCW file.
To Edit an exiting part. Click the local menu option Edit Existing Symbol. 
You can edit either the content or the parameters. Content is the physical geometry.
When finished, click OK and the part is saved with the changes.