412 Modern Welding Copyright Goodheart-Willcox Co., Inc. 15.3.2 Cutting Tips Before the cutting torch is turned on, the desired cut- ting tip must be inserted into the torch and aligned. Tips used in cutting outfi ts are removable parts that mate with the torch head. They are commonly held in the cutting torch head by a tip nut (large threaded nut). The mating (touching) surfaces of the tip and the torch head have been machined smooth. See Figure 15-7. Cutting tips normally have at least two orifi ces. One orifi ce, which is usually in the center of the tip, is for the cutting oxygen. One or more smaller orifi ces are for preheating the metal to be cut. Most cutting tips have an even number of preheating orifi ces, 2, 4, 6, or 8. For the best cutting quality, two of the preheating orifi ces are aligned with the cutting line, and the others are set on each side of the cutting line. See Figure 15-8. Regular cutting torches are designed to be used only for cutting. Combination torches can be confi gured for either welding or cutting. A cutting attachment con- nects to the combination torch body to change the torch from a welding torch to a cutting torch. The cost of such an attachment and the torch body is usually less than the cost of a separate welding torch and a cutting torch. For portable kits, this attachment saves space. To con- nect a cutting attachment, remove the welding tip tube and screw on the cutting attachment. See Figure 15-6. The operation of a torch with the cutting attach- ment is the same as the operation of a regular cutting torch. However, on a regular cutting torch, there is an oxygen torch valve, an acetylene torch valve, and a cutting oxygen lever. On a combination torch, the torch body has an oxygen torch valve and an acetylene torch valve. The cutting attachment has a second oxy- gen torch valve and a cutting oxygen lever. To make fl ame adjustments on a combination torch, the oxygen torch valve on the cutting attachment should be opened one or more turns. The torch valves on the torch body are then used to adjust the fl ames. The torch valves on the welding torch body must be turned off before the cutting attachment is disconnected. Cutting attachment Torch body CONCOA Figure 15-6. A cutting attachment screwed into place on a welding torch body. Tip nut Cutting tip Cutting torch head Sealing surfaces Goodheart-Willcox Publisher Figure 15-7. Typical cutting torch, tip, and tip nut arrangement. The smoothly machined surfaces in the torch head and on the torch tip form a gas-tight seal when the nut is tightened. Preheating flame orifice Cutting oxygen orifice Cutting line (axis) Goodheart-Willcox Publisher Figure 15-8. Correct alignment of the preheating orifices on a cutting torch. Two preheating orifices should line up with the cutting line.