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      <title>Measurement position effect</title>
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      <div class="title_topic2" id="xps10_pagetitle">Measurement position effect</div>
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      <p class="para_topic">The measurement position effect examples demonstrate the effects that measurement positions have on the variation calculated by Tolerance Stackup Validation.</p>
      <div class="title_division">Case 1</div>
      <p class="para_division">A simple block (2.0 inches on each side) has one tolerance, as shown in the figure below:</p>
      <ol type="1" start="1">
         <li>
            <p class="para_item">The left face of the block is considered a datum (Datum A). The opposite face, the right face, has a directed dimension of 2.0+/-0.01. The origin of this dimension is Datum A.</p>
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      <div class="figure">
         <p align="center"><img align="bottom" src="graphics/qs_meas_case1.gif"></p>
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      <div class="title_figure">Block with one tolerance</div>
      <p class="para_division">In the figure above:</p>
      <ul>
         <li>
            <p class="para_item">The P1 points are the default points: the centroids of the two faces (the Datum A face and the opposite face)</p>
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         <li>
            <p class="para_item">The P2 points are on the center of each face's top edge</p>
         </li>
         <li>
            <p class="para_item">The P3 points are on the center of each face's side edge (front)</p>
         </li>
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      <p class="para_division">Define 3 linear measurements between each point and the corresponding point on the opposite face, and run a Tolerance Stackup Validation analysis, as shown in the figure below:</p>
      <div class="figure">
         <p align="center"><img align="bottom" src="graphics/qs_meas1_pts.gif"></p>
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      <div class="title_figure">Measurements P1, P2, and P3</div>
      <p class="para_division">Here is the summary in the information window:</p>
      <p align="center"><img align="bottom" src="graphics/qs_meas1_info.gif"></p>
      <p class="para_division">In this case, the variation between the two faces does not depend on the position of the points. All three measurements gave the same answer. This is because the two features are controlled by a location tolerance; they move between the minimum (1.990) and the maximum (2.010). The points that lie on each feature follow that feature.</p>
      <div class="title_division">Case 2</div>
      <p class="para_division">In this case, the features are controlled by an orientation tolerance:</p>
      <div class="figure">
         <p align="center"><img align="bottom" src="graphics/qs_meas_case2.gif"></p>
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      <div class="title_figure">Block with orientation tolerance</div>
      <p class="para_division">After running the same calculation as in Case 1, the output in the Information window is:</p>
      <p align="center"><img align="bottom" src="graphics/qs_meas2_info.gif"></p>
      <p class="para_division">In this case, unlike in Case 1, the variation of the three points differs: the variation of the points measured at the centers of the faces (P1) is zero, while the variation of the points on the faces' edges (P2 and P3) varies by 0.1.</p>
      <p class="para_division">This is because the faces are &quot;tilting&quot; around the P1 center points, so no variation is shown in those points. However, the edges of the tilted faces (P2 and P3) move according to the parallelism tolerance of 0.01.</p>
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