Bending and Forming

For students of BCIT's Aviation "M" maintenance program, Level 3 concentrates on standard processes such as sheet metal bending and forming. The techniques of calculating bending allowance, setback, and sight lines are standard topics. This clip will quickly outline the basics of a 90-degree sheet metal bend.

[@Hunter_Bauss]

Thank you Sir! Im currently enrolled in an A/P program and have to make part of a rudder, this was a great review. Although you didn't show the math and marking your part.

[@Riveteer]

@davetileguy
I don't know which basic sheet metal bend allowance calculator you're using - perhaps it is already built into the calculations. For aviation, where we require accuracy to .oo1" or tighter, we need to use setback to establish the exact correct location of the metal when it is inserted into the bending brake. Setback is merely the thickness added to the radius: SB = R + T.

[@ExploringCabinsandMines]

HELP Why would a basic sheet metal bend allowence calculator not include setback??whats the point of giving an incomplete answer.? no one has a setback calculator.

[@rollformingbrotherunion4091]

nice, i am leaning metal forming, thanks

[@ScaredCivilian]

3x mat. + br x .437 = your bend allowance.

[@Ranar_equipment]

helpful

[@Dingo149]

how do you know where to place the sight line?

[@Riveteer]

The sight line is placed at a distance of one bend radius from the Bend Tangent Line. For example, if you are using a 1/8" radius, measure .125" from the BTL towards the middle of the bend allowance area. The sight line will not likely be the center of the bend allowance. Personally, I mark the sight line as a dotted line on the metal, to differentiate from the Bend Tangent lines. Be careful which end of the metal you insert into the bending brake.