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      <title>Selecting Geometry</title>
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      <div class="title_topic5" id="xps10_pagetitle">Selecting Geometry</div>
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      <p class="para_topic">The system determines where to apply flow cutting based on bi-tangency contact points and the angle of concavity between Part Surfaces. The surfaces may be selected in any order. If desired, you may select all surfaces in the part, or select a solid body allowing the system to determine which surfaces to utilize. A cut area in a mill area group may also be used to specify the faces to be included.</p>
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                  <p class="para_note_body"> NOTE: When selecting a Tool for the Flow Cut Drive Method, it is recommended that Ball Nose Tools be used for the best results. Unsatisfactory results in the tool path can occur if Bull Nose or Flat Nose tool is used.</p>
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      <p class="para_topic">To generate a Cutting move, the tool must contact the two part surfaces at two distinct points. Flow Cutting will not occur in areas where the curvature of the surface is larger than the corner radius of the tool as illustrated below. It will occur, however, in areas where the curvature of the surface is equal to or less than the corner radius of the tool, allowing bi-tangency contact points.</p>
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      <div class="title_figure">Bi-Tangency Contact Points</div>
      <p class="para_topic">In generating a Cutting move, the two Part Surfaces must form a relative angle between 0 and 180 degrees, but need not be adjacent to one another. This relative angle, called the Angle of Concavity, is defined by two vectors, each passing through a Contact Point and each tangent to a Part Surface.</p>
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         <p align="center"><img align="bottom" src="graphics/angl_concav.gif"></p>
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      <div class="title_figure">Angle of Concavity</div>
      <p class="para_topic">The tool path is created only where the angle of concavity is smaller than the specified Maximum Concavity angle. If the Angle of Concavity is too wide and exceeds the specified Maximum Concavity angle, then the Cutting Move is not created.</p>
      <p class="para_topic">The Angle of Concavity may be constant or it may vary between the two surfaces. If it varies, the tool retracts where the Angle of Concavity exceeds the Maximum Concavity angle, and then engages again where the Angle of Concavity is less than or equal to the Maximum Concavity angle as illustrated below.</p>
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         <p align="center"><img align="bottom" src="graphics/170deg_maxconcav.gif"></p>
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      <div class="title_figure">179 Degree Maximum Concavity Angle</div>
      <p class="para_topic">The Flow Cut Drive method allows you to define or inherit the Cut Area geometry in the same way as the Area Milling Drive Method. You may select Surface Regions, Sheet Bodies, or Faces as the cut area. The system recognizes the concave valleys within the cut area and the concave valleys formed by the cut area and the part geometry. The system excludes the valleys formed by the cut area and check geometry.</p>
      <p class="para_topic">In the Fixed Contour Dialog, choose Cut Area and Select to define the cut area geometry. If you do not specify a cut area, the system will use the entire defined Part Geometry (excluding areas not accessible by the tool) as the cut area.</p>
      <p class="para_topic"> <img align="bottom" src="graphics/cutarea_surfreg.gif" border="0">   
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