3 Square Throat-Square Heel Elbow-No Seams
-
Study the shop drawing. Remember that the first number for the duct size is always what we “see in the view”. The second number is the depth, or hidden view
- Calculate the blank sizes
- Cheek
- The drawing shows an opening size of 4” and a throat of 4”. So the horizontal dimension is 8”. Because the fitting is symmetrical, the vertical dimension is the same, 8”. Our blank size is 8”x 8”
- The drawing shows an opening size of 4” and a throat of 4”. So the horizontal dimension is 8”. Because the fitting is symmetrical, the vertical dimension is the same, 8”. Our blank size is 8”x 8”
- Throat
- The throat is show as 4” x 4”. So we can use perimeter to calculate the length. This gives us 8”. The second dimension comes from the depth of the opening, given at 6”. So our blank size is 8” x 6”
- The throat is show as 4” x 4”. So we can use perimeter to calculate the length. This gives us 8”. The second dimension comes from the depth of the opening, given at 6”. So our blank size is 8” x 6”
- Heel
- Because the throat is 4” and the opening is 4”, to get to the outside where the heel sits, it measures 8”.That gives us a perimeter of 16”. Again we can use simple math to calculate 8” + 8”= 16”. The second dimension comes from the depth of the opening, given at 6”. So our blank size is 16” x 6”
- Because the throat is 4” and the opening is 4”, to get to the outside where the heel sits, it measures 8”.That gives us a perimeter of 16”. Again we can use simple math to calculate 8” + 8”= 16”. The second dimension comes from the depth of the opening, given at 6”. So our blank size is 16” x 6”
- Cheek
- Shear the blanks out. We’ll draw out all parts for this one
- Mark all parts with an arrow for airflow
- Layout the parts
- Cheek
- From the outside, mark the opening at 4” for both ends of the fitting. Square the lines to create the throat section. Notice we always mark the opening, it is the most important feature of the fitting
- Heel and Throat
- Mark the perimeter calculated. There will be a bend at the mid point of both the heel and throat
- Mark the perimeter calculated. There will be a bend at the mid point of both the heel and throat
- Cheek