Instruction Manual Section Five
II. GRINDING TAPS OVER 1 INCH IN DIAMETER
A. Equipment:
The same equipment is required as is used for smaller taps, with the addition
of the B641C .800 inch Collet, plus the following items: B647P Driver for the
tap shank; A261C Spring Center or B922R Quick Release Spring Center
Tailstock.
B. Set-up Procedure:
1. Insert the B641C .800 inch collet in the spindle and tighten.
2. Insert No. B647P Tap Driver in the B641C .800 inch collet and tighten.
3. Mount either a tailstock with a Spring Center or a Quick Release Spring
Center Tailstock on the right-hand end of the table to receive the cutting
end of the tap (see Photo 54).
4. Insert the tap. The tap shank is held in the driver while the center of the
tap cutting end is held with the spring-center tailstock.
5. Proceed as with taps under 1 inch diameter, described in steps I, B to I.
III. SALVAGING BROKEN TAPS
A. Insert the broken tap in the fixture in the same way as when sharpening a tap.
Tighten as in step l-C-3.
B. Procedure for Grinding:
1. Remove the Lift Cam (see Step l-F-2 for access).
2. Bring the broken end of the tap into contact with the edge of the wheel
(see photo 55) and centered with the wheel center.
3. While advancing the table, rotate the tap by the fixture handwheel in the
opposite direction to that in which it cuts.
4. Grind the broken end of the tap off by rotating the tap against the wheel
until a smooth, square end is obtained.
5. Replace the correct Lift Cam, select the proper Index Disc, and sharpen
the tap as in steps I, B to I.
IV. GRINDING THE FLUTE CUTTING FACES OF THE TAP
Occasionally it is desirable to sharpen the teeth cutting faces of the tap from
where cutting begins on the chamfer back to the rear of the cutting teeth. This
is similar to grinding the teeth faces on form relieved cutters. This may be
accomplished with the use of the B947 fixture and a toothrest set-up. However,
for taps with spiral flutes, use of a fixture such as the B942 will be necessary to
achieve ease of rotation against the fixed toothrest.
A. Initial Set-up:
1. Choose a straight wheel with an appropriate diameter and width forming
a radius on its periphery to approximate that of the tap's flute gullet.
2. Position the tap fixture at the left end of the grinder table and set its
base swivel to 0 degrees so that its housing and spindle will be parallel
with the grinder table. Insert the tap as described in step l-G and then
go back to step l-E following the process as described but remove the
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