Page 56 - CITS - Fitter Trade Practical - Volume -2
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FITTER - CITS

           Internal threading blind holes using hand taps holes)

           Objectives: At the end of this exercise you shall be able to
           •   cut internal threads using hand taps.



           Drilling a blind hole
           Determine the tapping drill size using the table for tapping drill sizes.
           Drill a blind hole using the depth stop arrangement. The depth of the tapping hole should be slightly more than
           the depth of the required thread. (Fig 1)

               Fig 1

















           Procedure for threading
           Remove metal chips, if any, from the blind hole by turning it upside down and slightly tapping it on a wooden
           surface.
              Note: Do not clear the chips by blowing as it can cause injury to your eyes.

           Screw a matching nut on the first tap to act as a depth stop. (Fig 2)


               Fig 2



















           Thread the blind hole until the nut touches the plate surface.
           Remove the chips from the hole frequently, using a flattened and bend wire. (Fig 3)
           Finish tapping the hole with intermediate and bottoming tap. Set the nut to control the depth of the thread. (Fig 4)













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                                            CITS : C G & M - Fitter - Exercise 62
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