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Situation: Split draft occurs when the core and cavity steel from a tool pass next to each other to form part geometry. Such is the case in the battery door tabs example below.
Solution: To correctly draft this scenario (better known as a shutoff), the sweep commands are often used.
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Side walls are drafted to be made from core.
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Side view of battery door. Note undercut above tabs.
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1. Using the Draft command, draft the side wall surfaces. (This has already been done in this example.)
2. By using a sweep or a variable section sweep (pivot dir), create the opposing draft over the tabs. You will have to do this twice—once for each tab.
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Using a variable section sweep (pivot dir) to create draft and remove undercut.
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3. Notice that the sides of the geometry you created in the previous step do not line up with the side of the tabs. Use surface copies and tweak replaces to match the sides of the draft geometry to the tabs.
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Copy the side surfaces and replace sides created from the variable section sweep.
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Drafting the side walls.
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4. Add adequate draft to the side walls using the Draft command to complete the shutoff. Note: Use at least 5 degrees of draft on shutoff surfaces to minimize tool wear and to prevent flash in your parts. 
David Low is a project engineer at Digital Innovations, LLC in Lincolnwood, Illinois, USA. This article is based on his presentation at the 2002 PTC/USER World Event in Atlanta, Georgia. He can be reached by e-mail at dlow@digitalinnovations.com.
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