Smithy MIDAS MI-1220 LTD, Operator'S Manual, Page: 57 / 133

move the crossfeed lever down. Pull the lever up at the end of the cut to stop the cutter
travel.
Caution
Remember caution must be taken to not run the powerfeed past their limits of travel.
As part of the normal operation, procedures, run each axis through the entire
length of the proposed machining operation before engaging the powerfeed to
assure there is sufficient travel to accomplish for the desired task. Failure to so could
result in running the power feed to the end of its mechanical limit. This is what is
known as a "CRASH". A crash can cause damage to the work piece and severe
damage to the machine.
Figure 12.2 With a half-center you can extend the tool across the entire face of the work.
Knurling
Strictly speaking, knurling is not a machining operation because no metal is cut. It is a
forming operation in which patterned knurls are pressed into the work, depressing and
raising the surface of the metal into a pattern. As with all other forming operations, your
work can be no better than the pattern, your knurling no better than the knurls. Be sure
the knurls are sharp, clean-cut (preferably hob-cut), and properly hardened.
To make a true, uniform knurl, maintain uniform pressure on both knurls. Select a
self-centering knurling tool that equalizes pressure on the knurls automatically and is
strong enough to withstand end and side thrusts. Operate the lathe at the slowest speed
(160 rpm).
Knurling exerts extreme thrust against centers and bearings. You can lessen this thrust
materially by feeding the knurling tool at a slight angle off from perpendicular to the line
of the workpiece. This engages the right side of the knurl first (Figure 12.3).
Place a few drops of oil on the workpiece and knurling tool. Start the rolls of the
knurling tool from the right-hand scribe line and feed them in until the knurl reaches a
depth of 1/64". Then stop the lathe and inspect the work. If the knurl is not clear-cut,
adjust the tool in or out as needed.
Midas 1220 LTD Operator’s Manual
12-2
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