Copyright Goodheart-Willcox Co., Inc. May not be reproduced or posted to a publicly accessible website. Unit 22 Bending Metal 233 Inside Dimensions If you are given the inside dimensions, add all the inside lengths. Then add 1/2 the metal thickness for each 90° bend. 200 mm + 300 mm + 400 mm = 900 mm + 3 mm + 3 mm + 3 mm = 909 mm Flat-out length is 909 mm. Cylinder A piece of metal bent into a cylinder has two diameters—an inside diameter and an outside diameter. The difference between the inside diameter and the outside diam- eter is twice the thickness of the metal, as shown in the following illustration. When given the job of bending a piece of metal into a cylinder, you will need to know either the inside or outside diameter, as well as the thickness of the metal. You must also know how to calculate the circumference of a circle (refer to Unit 19). With this information, you can calculate the fl at-out length. Outside Diameter To determine fl at-out length when you are given the outside diameter, calculate the circumference using the outside diameter minus the metal thickness. 400 mm 6 mm 200 mm 300 mm 200 mm Inside diameter 210 mm Outside diameter Goodheart-Willcox Publisher Goodheart-Willcox Publisher