TABLE OF CONTENTS The discussion to this point of the chapter has dealt with cutting tools and scrapers to produce countersinks and chamfers. Grinding tools can also produce countersinks and are used for hard or very abrasive materials. There are few tools available for this purpose compared to the many already discussed.
Fig. 3-166 shows a 1/2-in. diameter diamond-plated countersink having 100 grit diamond. It is officially called a "router bit" or a "countersink router bit" by its manufacturer. This particular tool comes with abrasive sizes from 100 down to 220 grit diamond particles. This medium grit diamond countersink bit is used for glass routing where a chamfer is needed. The 1/4-in. (6.4-mm) shank fits router systems and fractional collets. Diamond tool coolant is normally directed at the point of cut with this tool. The OAL of this tool is 2 in. (57 mm), the shank is 1/4 in. (6.4 mm) and the recommended speed for it is 8000 rpm.
Fig. 3-167 shows a much larger diamond-plated countersink. This particular tool is built up with three layers of electroplated diamond for longer life and faster cutting. The tool is designed for countersinking operations in materials such as glass, quartz, composites, graphite-epoxy, carbon, boron, fiberglass, marble, and many other materials. Designed for use on hole diameters from 1.5 in. (38.1 mm) to 2.5 in. (63.5 mm), Table 3-116 illustrates the...
