Example 1 Bend radius = 0.22-inch Material thickness = 0.063-inch Bend angle = 90º ML 1 = 2.00/ML 2 = 2.00 Use a straightedge to connect the bend radius (0.22-inch) at  the top of the graph with the material thickness at the bottom  (0.063-inch). Locate the 90° angle on the right hand scale and  follow this line horizontally until it meets the straightedge.  Follow the curved line to the left and find 0.17 at the left side.  The X factor in the drawing is 0.17-inch.  [Figure 4-133] Example 2 Bend radius = 0.25-inch Material thickness = 0.050-inch Bend angle = 45º ML 1 = 2.00/ML 2 = 2.00 Figure 4-134  illustrates a 135° angle, but this is the angle  between the two legs. The actual bend from flat position is  45° (180 – 135 = 45). Use a straightedge to connect the bend  radius (0.25-inch) at the top of the graph with the material  thickness at the bottom (.050-inch). Locate the 45° angle on  the right hand scale and follow this line horizontally until  it meets the straight edge. Follow the curved line to the left  and find 0.035 at the left side. The X factor in the drawing  is 0.035 inch.  Total developed width = (Mold line 1 + Mold line 2) – X factor Total developed width = (2 + 2) – .035 = 3.965-inch Total developed width = (Mold line 1 + Mold line 2) – X factor Total developed width = (2 + 2) – .17 = 3.83-inches The bend radius necessary to bend a part can be found in  the part drawings, but if it is not mentioned in the drawing,  consult the SRM for a minimum bend radius chart. This  chart lists the smallest radius allowable for each thickness  and temper of metal that is normally used. To bend tighter  than this radius would jeopardize the integrity of the part.  Stresses left in the area of the bend may cause it to fail while  in service, even if it does not crack while bending it.  The brake set up for box and pan brakes and cornice brakes  is identical.  [Figure 4-135]  A proper set up of the sheet  metal brake is necessary because accurate bending of sheet  metal depends on the thickness and temper of the material  to be formed and the required radius of the part. Any time a  different thickness of sheet metal needs to be formed or when  a different radius is required to form the part, the operator  needs to adjust the sheet metal brake before the brake is  used to form the part. For this example, an L-channel made  from 2024 –T3 aluminum alloy that is 0.032-inch thick will  be bent. Figure 4-134.  Example 2 of J chart. Figure 4-135.  Brake radius nosepiece adjustment.  Figure 4-133.  Example 1 of J chart.  Using a Sheet Metal Brake to Fold Metal Step 1: Adjustment of Bend Radius 2.0" 0.5" R = 0.25" 135° 2.0" 2.00" 0.063" R = 0.22" 2.00" 4-69