7 Round Y-Branch

 

 

  1. Make sure the fitting is sized correctly. Remember some of the sizing rules for y-branches: the crotch height must be ¾ of the base diameter (or 1.5x the radius), the small openings must equal the large- A2 + B2 = C2 can be used to size the fitting correctly

 

 

  1. Draw a complete elevation view of 1 side of the fitting. The second side would be traced or a second pattern would be developed separately

 

 

  1. Draw profiles on the small end, large end and the crotch

 

 

  1. Using the left side of the large end and the crotch profiles, create an ellipse to indicate the true shape of the crotch. Run the profile division lines from the crotch horizontally and the left side of the large profile divisions vertically to create cross points which create the ellipse

 

 

  1. Label the elevation view with numbers, similar to a round taper. Going back and forth from top to bottom. Notice where the crotch intersects with the base is 1 point. Both profile lines indicate the same point, which is labeled point 8

 

 

  1. We will use “Difference in Profile” to develop the pattern

 

  1. Start the pattern with a vertical line 1-2. Remember this is a true length in the elevation view

 

 

  1. Take the length of line 2-3 and swing it 90 to profile height 3

 

  1. Pick up the true length of line 2-3 and swing it from point 2 on the pattern

 

 

  1. Pick up a step-off and swing it from point 1 to complete point 3

 

  1. Take profile height 3 and place it on profile height 4, starting from the outside inwards

 

 

  1. Take line 3-4 and swing it down to point 4, 90 to the difference in profile

 

 

  1. Pick up the true length of line 3-4 and swing it from point 3 on the pattern

 

 

  1. Pick up a step-off and swing it from point 2 to complete point 4

 

 

  1. Take profile height 4 and place it on profile height 5, starting from the outside inwards

 

 

  1. Take line 4-5 and swing it up to point 5, 90 to the difference in profile

 

  1. Pick up the true length of line 4-5 and swing it from point 4 on the pattern

 

  1. Pick up a step-off and swing it from point 3 to complete point 5

 

  1. Take profile height 5 and place it on profile height 6, starting from the outside inwards

 

  1. Take line 5-6 and swing it down to point 6, 90 to the difference in profile

 

  1. Pick up the true length of line 5-6 and swing it from point 5 on the pattern

 

  1. Pick up a step-off and swing it from point 4 to complete point 6

 

  1. Continue with the difference in profile method, until point 14 is complete

 

 

  1. Use a straight edge and a curve to draw in the object lines

 

 

  1. Add on any seam allowances

License

Pattern Development: Sheet Metal Level 3 Copyright © by bcoey. All Rights Reserved.

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