Calculating A Rolling Offset In Sheet Metal

Most sheet metal materials will conform to the calculations.

Calculating a rolling offset in sheet metal.

It allows you to determine either the size of raw material needed or the number of gore sections to fit on your available material. Here you would subtract the material thickness from the specified offset. Cells on the right will output the desired values. You then need to take the square root of the result to get the true offset.

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. In the example the square root of 208 14 42 inches. Air bending one of the three types of bending for sheet metal where the outside mold line is not pressed against the die. Sheet metal cone calculator view the cone instructions below to learn how to manually layout the flat pattern for a truncated cone in single or multiple gore sections.

The resulting number is the offset depth as measured from the material surface. The first number you need to find when calculating a rolling offset is the true offset which is found using pythagoras theorem. This page also includes a link to a on line sheet metal bend allowance calculator. Sheet metal calculator bend allowance equations and calculator.

Calculate the square root of the number to find the rolling offset. This is used to calculate the back stop location when working off of a flat pattern. 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. This simply means that the offset squared plus the rise squared will equal the true offset squared.

Air bend force chart a chart used to calculate the tonnage required for a bend based on thickness tooling and length. 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. Say you need to form an offset specified as 0 156 inch in 0 059 in thick material. The length of the material will then be 11 75 x pi or 36 9137 inches.

Step 2 finding the setback and diagonal. The following illustration shows the equation calculation for determining the bend allowance when forming sheet metal. 0 059 0 097 in.