6. Thread cutting by taps on through holes

Internal threads are produced by thread cutting by using taps. The workpiece surfaces are processed by means of bores.

- Work is made in the chuck.

- The workpieces are clamped in the extended chuck jaws in order to guarantee true running and top surface quality as the parts have generally already been processed.

- The tap wrench is positioned on the square of the tap.

- The tap is positioned by means of the tailstock tip which is aligned to the centring of the tap.

Figure 18. Positioning the tap

1 tap, 2 tap wrench, 3 tailstock quill, 4 workpiece

- The tap wrench holder is positioned on a surface clamped into the tool holder.

- Generally speaking, the machine tap is used (economical mode of operation).

- Turn back the tap several times to remove the chips and clean the chip grooves.

- Ensure proper cooling and lubrication.

- Turn back the tap by hand upon completing the work sequence.

- The thread is checked by means of a thread ring mandrel.

Figure 19. Normal thread ring mandrel

1 thread mandrel for minor diameter

What must be heeded when thread cutting by taps?
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