File Card: When filing the soft metals, the small pieces of metal will tend to clog the teeth. If the file is not cleaned,this small piece of metal will scratch on the surface of the work. We call it pinning. This case isfrequently appeared when applying a new smooth file on the soft metals. The pinning can be removedwith a File Card as shown in figure 23, which is a wire brush mounted on a block of wood. Sweep thefile card along the grooves on the file until the pinning is removed.
Reamer: Functions of reamer are
1. to control the diameter of a hole
2. to improve the internal surface finish
3. to improve the roundness of the hole
Reamer is made of hardened High Carbon Steel or High Speed Steel. It is classified into hand reamer
and machine reamer.
1. Hand Reamer: Hand reamer (figure) has two types of flutesstraight and spiral flutes. The spiral flutes handreamer has a left hand spiral flutes. The purpose ofthe design is to prevent the reamer "screw in" thehole.
2. Machine Reamer: Machine reamer (figure 34) has a straight shank ortaper shank (Morse taper). The taper shank can fitdirectly into the spindle of a machine while thestraight shank is hold by the collet.
3. Expanding Reamer/Adjustable Reamer: The cutting diameter can be slightly varied byadjusting an inner taper against the loss cuttingblades as shown in figure 35. This type is usedprimarily for repetitive work to maintain a consistentsize throughout.
Counter bore: is a cylindrical flat-bottomed hole that enlarges another coaxial hole, or the tool used to create that feature. A counterborehole is typically used when a fastener, such as a socket head cap screw, is required to sit flush with or below the level of a work piece’s surface.
Countersink Drill: is a conical hole cut into a manufactured object, or the cutter used to cut such a hole. A common use is to allow the head of a countersunk bolt or screw, when placed in the hole, to sit flush with or below the surface of the surrounding material.
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