Smithy Midas 1220 LTD - Manual (Page 58)

stroke. Use a clean, dry file and keep the workpiece clean, as well. Wipe the workpiece
dry and clean if you've used coolant or cutting oil. Never hold the file stationary while the
workpiece is revolving.
Figure 11.3 With a file, take full strokes at an oblique angle; never hold the file still.
For an even finer file finish, rub railroad chalk into its teeth. This provides additional
lubrication and absorbs filings. Do not use blackboard chalk.
After filing off the machining marks, polish the workpiece with emery or other abrasive
cloth. Keep the lathe turning at high speed and spread a few drops of oil on the
workpiece. Don't stop moving the cloth.
Figure 11.4 You can polish a workpiece with an abrasive cloth and oil.
Taper Turning
There are two ways to turn a taper: with the compound rest and by setting over the
tailstock. In both methods, the cutter must engage the work on dead center if the taper
is to be accurate.
Compound rest. Tapers cut with the compound rest are usually short, abrupt angles, such
as centers, bevel gear blanks, and die parts (Figure 11.5). In general, these are not
considered taper turning, which applies to machining longer, more gradual tapers.
Setting over the tailstock. Cutting tapers by setting over the lathe tailstock involves
misaligning the lathe centers. The lathe centers move from their position parallel to the
tool's transverse travel, giving the desired degree of taper (Figure 11.6). The tailstock has
a set-over scale calibrated both forward and backward from the straight turning or
zeroing point for measuring set-over distances.
Midas 1220 LTD Operator’s Manual
11-4
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