A hole finder is a tool used to transfer existing holes in aircraft structures or skin to replacement skin or patches. See figure 13-5. The tool has two leaves parallel to each other and fastened together at one end. The bottom leaf of the hole finder has a teat installed near the end of the leaf that is aligned with a bushing on the top leaf. The desired hole to be transferred is located by fitting the teat on the bottom leaf of the hole finder into the existing rivet hole. The hole in the new part is made by drilling through the bushing on the top leaf. If the hole finder is properly made, holes drilled in this manner will be perfectly aligned. A separate duplicator must be provided for each diameter of rivet to be used.

Figure 13-5.-Hole finder.

There are several types of skin fasteners used to temporarily secure parts in position for drilling and riveting and to prevent slipping and creeping of the parts. C-clamps, machine screws, and Cleco fasteners are frequently used for this purpose. See figure 13-6. Cleco fasteners come in sizes ranging from 1/1 6 to 3/8 of an inch. The size is normally stamped on the fastener, but may also be recognized by the following color code:

The Cleco fastener is installed by compressing the spring with Cleco pliers (forceps). With the spring compressed, the pin of the Cleco is inserted in the drilled hole. The compressed spring is then released, allowing spring tension on the pin of the Cleco to draw the materials together. Clecos should be stored on a U-channel plate to protect the pins of the Cleco. Storing Clecos at random among heavy tools will result in bent pins.