Transitionial Fitting Fabrication Flashcards
When are transitional fittings used
A)
B)
A) Change aspect ratio
B) move duct for architectural reasons
2 reasons the use of transitional fittings are avoided
Time and money
3 joints used to join transitional fittings
S+D, standing drive CP, proprietary
Why must a S+D joint be adjusted
S cleat must be straight
What must be done to the net pattern for each S+D connection
Reduce length of net pattern by 1”
What must be developed first when developing the cheeks for a curved runner pattern?
Pattern/flat view
What math concept is used when building transitions from plan view
Pythagoras
What should determine which sloped side gets pocket allowances for 2 side flat and why
Side that has the most slop and less angle for transfer of angle notch
When assembling a transitional fittings, what should be done before assembly?
Form seams and edges
Form Pittsburgh locks
Why would the throat and heel be fastened to one cheek instead of fastening with cheeks to the heel or throat?
Easier to assemble
What does FOB/FOT refer to
Flat on back or flat on top
What 2 types of joints are assembled using drive cleat
Slip and drive
Stand drive CP
How high off the duct is a 1½” standing drive connection
1”
What is the formula for hammerlock connection
3W 3 times the width of the seam
Method of notching when Pittsburgh is at an angle, why do we use it.
Transfer of angle
Removes material that would interfere with duct connection
