TABLE OF CONTENTS Single point threading can be a relatively easy job for both programming and machining, if all goes well. Fortunately, that is the case most of the time, but there are many situations that may present potential problems. At least two of them can be prevented:
Programming spindle speed incorrectly
Programming cutting feedrate incorrectly
The first item relates to spindle speeds that are either too high or too low for the given thread, the second item relates to certain threads being cut over a long length. Both potential problems can be eliminated mathematically, during the part programming process.
Every CNC machine tool is designed within certain parameters that relate to its various dimensions and capacities. On an every day basis, the part programmer must generally consider two of these parameters in most machining operations, but particularly in single point threading:
Range of spindle speeds
Maximum cutting feedrate
For typical turning and boring, the actual programmed spindle speed range and cutting feedrate fall comfortably within the machine specifications. Consider these features of medium to large size CNC lathes, as defined by the machine manufacturer (samples only):
| Spindle Speed | Minimum | Maximum |
| 125r/min | 3000 r/min |
| Maximum Cutting Feedrate | Metric | Imperial |
| 6350 mm/min X-axis 12700mm/min Z-axis | 250 in/min X-axis 500 in/min Z-axis |
Note that the imperial amounts are equivalent to the metric amounts. In the chart are only examples that will be used for further calculations of various threads. Also note, that some machines may have a lower maximum feedrate for...
