LATHE OPERATIONS - OD1645 - LESSON 1/TASK 1
both ends of the guide bar are used to make this adjustment.
A sliding
block which rides on a dovetail on the upper surface of the guide bar is
secured during the machining operation to the cross-slide bar of the
carriage, with the crossfeed screw of the carriage disconnected. Therefore,
as the carriage is traversed during the feeding operation, the cross-slide
bar follows the guide bar, moving at the predetermined angle from the ways
of the bed to cut the taper.
It is not necessary to remove the taper
attachment when straight turning is desired; the guide bar can be set
parallel to the ways, or the clamp handle can be released permitting the
sliding block to move without affecting the cross-slide bar. The crossfeed
screw can be re-engaged to permit power to the crossfeed and control on the
cross-slide from the apron of the carriage.
(e) A telescope taper attachment is similar to the plain attachment
(which was discussed in the preceding paragraph) except that it is equipped
with a telescopic crossfeed screw which eliminates the necessity of
disconnecting the crossfeed screw.
To use the telescopic attachment, first set the tool bit for the required
diameter of the work and engage the attachment by tightening the binding
screws.
The location and the number of binding screws depends upon the
design of the attachment. The purpose of the binding screws is to bind the
cross-slide so that it may be moved only by turning the crossfeed handle or,
when loosened, to free the cross-slide for use with the taper attachment.
To change back to straight turning with the telescopic attachment, it is
necessary only to loosen the binding screws.
(f) When cutting a taper using the taper attachment, the direction of
feed should be from the intended small diameter toward the intended large
diameter.
Cutting in this manner, the depth of cut will decrease as the
tool bit passes along the workpiece surface, assisting the operator in
preventing possible damage to the tool bit, workpiece, or lathe by forcing
too deep a cut.
(g) The length of taper the guide bar will allow is usually not over 12
to 24 inches, depending on the size of the lathe. It is possible to machine
a taper longer than the guide bar allows by moving the attachment after a
portion of the desired taper
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