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      <title>Fixed and Variable Contour</title>
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      <div class="title_topic2" id="xps10_pagetitle">Fixed and Variable Contour</div>
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      <p class="para_topic">Fixed and Variable Contour are machining methods used to finish areas formed by contoured surfaces. They enable the tool path to follow intricate contours of very complex surfaces by allowing you to carefully control the Tool Axis and Projection Vector.</p>
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         <p align="center"><img align="bottom" src="graphics/varcont_drvsurf.gif"></p>
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      <div class="title_figure">Variable Contour Using Drive Surfaces</div>
      <p class="para_topic">Tool paths are created by projecting Drive Points to Part Geometry. Drive points are generated from Drive Geometry, such as curves, boundaries, faces, or surfaces, and projected along a specified projection vector to the Part Geometry. The tool then positions to the Part Geometry to generate the tool path.</p>
      <p class="para_topic">The following figure illustrates how an operation is created by projecting Drive Points from a bounded plane to a Part Surface. An array of Drive Points is first created within the boundary and then projected along a specified Projection Vector to the Part Surface.</p>
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         <p align="center"><img align="bottom" src="graphics/proj_drvpts.gif"></p>
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      <div class="title_figure">Projection of Drive Points</div>
      <p class="para_topic">The tool positions to contact points on the Part Surface. As the tool moves across the part from one contact point to the next, the tool path is created using the Output Cutter Location Point at the tip of the tool.</p>
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         <p align="center"><img align="bottom" src="graphics/bndry_drvmeth.gif"></p>
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      <div class="title_figure">Boundary Drive Method</div>
      <p class="para_topic">The Surface Area Drive Method provides additional control over both the Tool Axis and the Projection Vector. The following figure illustrates how an operation is created by projecting Drive Points from a Drive Surface to Part Surfaces. An array of Drive Points is first created on the selected Drive Surface and then projected along the specified Projection Vector to the Part Surfaces. The tool positions to the Part Surfaces at Contact Points. As the tool moves from one Contact Point to the next, the Tool Path is created using the Output Cutter Location Point at the tip of the tool. In this example, both the Projection Vector and the Tool Axis are variable and are defined as normal to the Drive Surface.</p>
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         <p align="center"><img align="bottom" src="graphics/surfarea_drvmeth.gif"></p>
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      <div class="title_figure">Surface Area Drive Method</div>
      <p class="para_topic">The following figure illustrates how a Tool Path is created directly from the Drive Points when there is no defined Part Geometry. An array of Drive Points is created on the selected Drive Surface. The tool positions directly on the Drive Points which become the Contact Points. In this example, the Tool Axis is variable and is defined as normal to the Drive Surfaces.</p>
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         <p align="center"><img align="bottom" src="graphics/toolpth_drvsurf.gif"></p>
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      <div class="title_figure">Tool Path on Drive Surfaces</div>
      <p class="para_topic">A Fixed Tool Axis remains parallel to a specified vector. A Variable Tool Axis constantly changes orientation as it moves along the Tool Path. If you specify Fixed Contour, only the Fixed Tool Axis options are available. If you specify Variable Contour, all Tool Axis options (except Fixed) are available.</p>
      <p class="para_topic">The Drive Method enables you to define the Drive Points required to create a Tool Path. Some Drive Methods allow you to create a string of Drive Points along a curve while others allow you to create an array of Drive Points within an area. Once defined, the Drive Points are used to create a Tool Path. If no Part geometry is selected, the Tool Path is created directly from the Drive Points. Otherwise, the Tool Path is created by projecting Drive Points to the Part Surfaces along the Projection Vector.</p>
      <p class="para_topic">The Projection Vector enables you to define how the Drive Points project to the Part Surface and the side of the Part Surface the tool contacts. The selected Drive Method determines which Projection Vectors are available. Projection Vectors can be defined for all Drive Methods except Flow Cut, which does not utilize Projection Vector. When machining directly on the Drive Geometry (Part Geometry is not defined), the Projection Vector is not used.</p>
      <p class="para_topic">In Surface Contouring, all Part Geometry is processed as bounded entities. Accordingly, since Surface Contouring entities are finite, the tool can position only to existing locations on the Part Geometry (and that includes the edge of an entity.) The tool cannot position to an extension of the Part Geometry. Drive Geometry, however, can be extended.</p>
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