Examine the Parameters.
Bring up the parameter definition table to examine the parameters on the part:
1. Select EDIT Parameters in MENU 2
Assuming that the top part is active. There should be five parameters defined:
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Bwid
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Gives the width of the bars between the air intakes. Set to 20.
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Inrad
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Gives the inner radius of each air intake. Set to 25.
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Outrad
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Gives the outer radius of each air intake. Set to 100
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Pt1
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A reference point. Pt1 is a geometry parameter, so its value will always correspond to the top corner of an air intake, no matter how this part is resized.
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Pt2
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A reference point. The value of Pt2 will always correspond to the bottom corner of Pt1's air intake.
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To prove that the parameters work as we say they do, try them:
1. Close the parameter definition table by picking OFF.
2. Select MENU 1. Remember that all value parameters are always available in the parameter value table on MENU 1.
3. Change the value for "Out_rad" to 120. Pick on the "Outrad" entry in the table and enter 120 from the keyboard.
4. Select Preview in SOLVE.
5. Notice how the hole configuration changes.
6. Restore the parameters to their original values when you've finished experimenting.
Take a look at the parameters on the exhaust ports now.
1. Make "slot_grid" the current part.
2. Preview a few variations of this part by inserting new values for the "Newrad" parameter and solving in Preview mode.
3. Set "Newrad" to 5 and solve in NoKeep mode.
4. Make the top part current.
The configuration of the parameters should give you an idea of the strategy we'll use to accomplish our task. We can easily vary the size and configuration of the four air intakes in the top part by changing the parameter values for "Bwid," "Inrad," and "Outrad." On the "slot_grid" part, we can vary the width of all three exhaust ports by entering a new value for the "Newrad" parameter. All that needs to be done now is to translate the area defined by "Bwid," "Inrad," and "Outrad" into a radius that can be fed to "Newrad." This is exactly what our macro, Do_it, does.