{"id":36,"date":"2021-12-09T13:08:44","date_gmt":"2021-12-09T18:08:44","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/ductfittings\/?post_type=chapter&p=36"},"modified":"2022-08-15T14:07:28","modified_gmt":"2022-08-15T18:07:28","slug":"ogee-offset","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/ductfittings\/chapter\/ogee-offset\/","title":{"raw":"Ogee Offset-No Seams","rendered":"Ogee Offset-No Seams"},"content":{"raw":"
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  1. [embed]https:\/\/www.youtube.com\/watch?v=XHg2qEKR_48[\/embed]\r\n\r\nStudy the shop drawing. Remember that the first number for the duct size is always what we \u201csee in the view\u201d. The second number is the depth, or hidden view.\r\n\"\"<\/li>\r\n \t
  2. Calculate the blank sizes.\r\n
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    1. Cheek- If we look vertically at the opening size of 4\u201d and the offset of 3\u201d, the dimensions total 7\u201d. The length is given at 7\u201d. So our blank size is 7\u201d x 7\u201d.\r\n\"\"<\/li>\r\n \t
    2. For the wrapper, we use a very specialized formula: (4x(\u221aO\u00b2+L\u00b2)-L)\/3. In our case, we get 7 13\/16\u201d. The second dimension comes from the depth, which is given at 6\u201d. That gives us a blank size of 7 13\/16\u201d x 6\u201d.\r\n\"\"<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t
    3. Shear the blanks out. We\u2019ll only draw out the cheek in this case because there is no layout to the wrapper.\r\n\"\"<\/li>\r\n \t
    4. Mark the cheek with an arrow for airflow. If you had sheared all the blanks, you would mark them all for airflow.\r\n\"\"<\/li>\r\n \t
    5. Mark the opening and the center of the opening at each end. Notice we always mark the opening, it is the most important feature of the fitting.\r\n\"\"<\/li>\r\n \t
    6. From here, we have 2 options to finish the layout, we will cover both.\r\n
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      1. Geometric Construction Method<\/strong>\r\n
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        • Draw a center line from end to end\r\n\"\"<\/li>\r\n \t
        • Divide that line into 4 equal parts (using ruler on a diagonal) and number the 3 points\r\n\"\"<\/li>\r\n \t
        • Create perpendiculars from points 1 and 3 aimed towards the offset\r\n\"\"<\/li>\r\n \t
        • The point where the perpendicular lines cross the outside of the blank size becomes the radius point for the arcs\r\n\"\"<\/li>\r\n \t
        • From these 2 points, set your compass to the inside and outside of the opening and swing arcs. A note: if you draw a diagonal line from radius point to radius point, this line will indicate where the lines transition along the ogee curve\r\n\"\"\r\n\r\n<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n \t
        • Math Method<\/strong>\r\n
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          • Using the formula (O\u00b2 x L\u00b2)\u00f7(4 x O) we will calculate a radius point at 6 1\/16\u201d\r\n\"\"<\/li>\r\n \t
          • Measure this distance vertically towards the offset, from the center of the opening.\r\n\"\"<\/li>\r\n \t
          • This point becomes our radius point. Set your compass to the inside and outside of the opening and swing arcs. A note: if you draw a diagonal line from radius point to radius point, this line will indicate where the arcs transition along the ogee curve\r\n\"\"\r\n\r\n<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ol>\r\n<\/li>\r\n<\/ol>","rendered":"
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