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"Advanced Milling Operations"
Woodruff Keyseat Cutting

Formed milling cutters are used to accurately duplicate the contour of a required surface. The woodruff keyseat cutter (Figure 1) is a form cutter that duplicates the shape of a woodruff Key (Figure 2).


Figure 1. Woodruff keyseat Cutter

Woodruff keys are used when keying or mating parts. Woodruff keyseats can be cut quicker than a straight keyseat. Woodruff keys are semicircular in shape and can be purchased in standard sizes.


Figure 2. Woodruff Key.

Woodruff keyseat cutters come in a straight tooth or a staggered tooth configuration. The shank is undercut next to the cutter to allow for clearance during cutting operations. Woodruff cutters over 2 inches in diameter are mounted on an arbor.

The size of the cutter is stamped on the shank. The last two digits of the number indicate the nominal diameter in eighths of an inch. The digit or digits preceding the last two digits indicate the nominal width of the cutter in thirty-seconds of an inch. Thus a 608 cutter like the one in Figure 1 above would be 8/8 or one-inch in diameter by 6/32 or three-sixteenths wide.

To cut a woodruff keyseat:

    1. Tram or align the head of the vertical milling machine.
    2. Layout the position of the keyseat.
    3. Set the shaft in a vise or on v-blocks and level the shaft parallel with the table.
    4. Mount the keyseat cutter in a positive lock style of holder.
    5. Start the spindle at the proper RPM for a form cutter and check the cutter rotation. Touch the bottom of the cutter to the top of the work piece using a piece of paper. Set the vertical graduated feed collar to the paper thickness.
    6. Move the work clear of the cutter. Raise the table half the diameter of the work (where you touched off) plus half the thickness of the cutter. Lock the knee of the milling machine.
    7. Touch off the cutter on the end of the shaft and find the center of the slot location on the shaft using the graduated dial of the milling machine. Lock the X axis traverse direction of the milling machine.
    8. Touch the revolving cutter to the work using a piece of paper as a buffer. Set the cross feed graduated dial to the paper thickness. Using the Machinery’s Handbook calculate the depth of the keyseat. Cut the keyseat to depth.