This simply means that the offset squared plus the rise squared will equal the true offset squared.
Calculating a rolling offset in sheet metal.
The following illustration shows the equation calculation for determining the bend allowance when forming sheet metal.
Most sheet metal materials will conform to the calculations.
Air bending one of the three types of bending for sheet metal where the outside mold line is not pressed against the die.
0 059 0 097 in.
The length of the material will then be 11 75 x pi or 36 9137 inches.
The first number you need to find when calculating a rolling offset is the true offset which is found using pythagoras theorem.
In the example the square root of 208 14 42 inches.
The resulting number is the offset depth as measured from the material surface.
Rolling offsets are used in the piping and sheet metal duct work trades a rolling offset changes the elevation and locaton of the piping or duct usually by using two fittings to offset around.
Say you need to form an offset specified as 0 156 inch in 0 059 in thick material.
Air bend force chart a chart used to calculate the tonnage required for a bend based on thickness tooling and length.
If you are rolling a ring with a 12 inch od out of 25 inch thick material the mean diameter of the ring will be 11 75 inches.
With this free online tool we quickly get the sheet metal bend deduction and therefore the sheet metal blank initial flat length from the finished part measurements.
You then need to take the square root of the result to get the true offset.
This is used to calculate the back stop location when working off of a flat pattern.
Rolling offsets run the rolling offset run function computes the run length a rolling offset based on the offsets and fittings.
Here you would subtract the material thickness from the specified offset.
Step 2 finding the setback and diagonal.
You only have to insert interior angle flange lengths k factor inside radius and material thickness.
This page also includes a link to a on line sheet metal bend allowance calculator.
Cells on the right will output the desired values.
Calculate the square root of the number to find the rolling offset.
Sheet metal calculator bend allowance equations and calculator.
