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      <title>Part preparation</title>
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      <div class="title_topic2" id="xps10_pagetitle">Part preparation</div>
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               <p class="para_td"><a class="links" href="javascript:void(0)" onclick="top.openFile('rapidprototyping/introduction.html');return(false);">Overview</a></p>
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               <p class="para_td"><a class="links" href="javascript:void(0)" onclick="top.openFile('rapidprototyping/pro_prototyping.html');return(false);">How To</a></p>
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               <p class="para_td">Options</p>
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               <p class="para_td"><a class="links" href="javascript:void(0)" onclick="top.openFile('rapidprototyping/error_mess.html');return(false);">Related Topics</a></p>
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      </table><br><p class="para_topic">Some details must be arranged in constructing the part so that a surfaced model can be successfully converted using Rapid Prototyping (STL).</p>
      <p class="para_topic">Make the edge curves start and end at the faces' corners. For example, if edge (A) is hooked (see the figure below), this edge is constructed so that the curve with the bend is one curve, with no curve end point at C. Then the adjacency checker cannot find where the hooked end matches to edge B. This will display as an error saying the edge does not have two surfaces. When preparing a surface part for rapid prototyping, avoid this situation.</p>
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      <p class="para_topic">The edge is hooked and adjacency is not correctly determined.</p>
      <p class="para_topic">All the surfaces together must form a closed shell. Any pair of surfaces with edges farther apart than the adjacency tolerance (as shown above) will not be matched, causing a hole in the model. In particular, suppose a part has two sets of ribs that cross each other:</p>
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      <p class="para_topic">Crisscrossing ribs cannot be matched at the corners. The two ribs at A run through each other. Rapid Prototyping cannot make a closed shell from these surfaces. The ribs at B are trimmed so that the surfaces' edges match at the corners. This is required at all surface edges, for Rapid Prototyping to make a closed shell.</p>
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