Civil Engineering Reference
In-Depth Information
Fig. 4.4. A diamond hone can be used to chamfer the corner on a cutter or to hone a
small radius on the corner.
FC3 cutters
FC3 cutters are commonly known as throwaway cutters as they are designed
to be used and then thrown away when worn out. Their cost is so small that,
at least in industry, it is not worth the expense of sharpening them. As their
name suggests, they normally have three flutes. They are available in many
sizes although their shank is normally
1
⁄
4
in (6mm) in diameter. I have seen
FC3 cutters with larger shanks such as 8, 10 or 12mm.
FC3 cutters have a parallel shank, and normally they have a flat on the side
of the shank for a grub screw. FC3 cutters are quite sharp, but I have found
that many makes of FC3 are not quite sharp enough for use on plastics so I
would stick to normal slot drills for plastics.
You can use FC3 cutters to cut narrow keyways in shafts to take a standard
key. If used with care, they will cut a keyway which is about 1 thou narrower
thanthenominalkeyorcuttersize.Youcanplungeatoneend,windthecutter
along by the length of the keyway required and then raise the cutter from the
slot. The key will probably need filing down very slightly to fit the keyway.
