Caution, Knurling – Smithy Midas 1220 XL User Manual

Page 70

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the lathe is turned on. Once the cutter has been positioned as per the above paragraph,

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 13.2 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 13.3).

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.

13-2

For Assistance: Call Toll Free 1-800-476-4849

Midas 1220 XL Operator’s Manual

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