AS 2181.1-1978

1 - AS 2181, PART 1-1978 SCREWING TAPS - GENERAL PURPOSE METRIC SCREW THREADS
4 - PREFACE
7 - CONTENTS
9 - SECTION 1. SCOPE AND GENERAL
9 - 1.1 SCOPE.
9 - 1.2 TERMS AND DEFINITIONS.
9 - 1.2.1 Terminology of the Thread Profiles.
12 - 1.2.2 General Terminology of Taps.
13 - 1.2.3 Terminology of Cutting Features.
13 - 1.3 TOLERANCE SYSTEM.
13 - 1.4 MATERIALS.
13 - 1.5 HEAT TREATMENT.
15 - 1.6 DESIGNATION AND MARKING.
15 - 1.6.1 Marking.
15 - 1.6.2 Designation for the Purpose of an Enquiry or Order.
16 - SECTION 2. GENERAL DIMENSIONS OF TAPS
16 - 2.1 SCOPE OF SECTION.
16 - 2.2 GENERAL DIMENSIONS OF STANDARD MACHINE AND HAND TAPS.
22 - SECTION 3. SCREW THREAD LIMITS FOR GROUND THREAD TAPS
22 - 3.1 SCOPE OF SECTION.
22 - 3.2 TAP CLASSES.
23 - 3.3 TAP PITCH DIAMETER TOLERANCE.
24 - 3.4 TAP MAJOR DIAMETER.
24 - 3.5 TAP MINOR DIAMETER.
24 - 3.6 TOLERANCE ON PITCH.
24 - 3.7 FLANK ANGLE TOLERANCE.
31 - 3.8 RUNOUT.
31 - 3.9 SELECTION OF TAP CLASS.
32 - SECTION 4. SCREW THREAD LIMITS FOR CUT THREAD TAPS
32 - 4.1 GENERAL.
32 - 4.2 TAP PITCH DIAMETER TOLERANCE.
32 - 4.3 TAP MAJOR DIAMETER.
32 - 4.4 TAP MINOR DIAMETER.
32 - 4.5 TOLERANCE ON PITCH.
32 - 4.6 FLANK ANGLE TOLERANCE.
33 - 4.7 RUNOUT.
36 - APPENDIX A - GENERAL DIMENSIONS OF LONG SHANK MACHINE TAPS
36 - A1 GENERAL.
36 - A2 GENERAL DIMENSIONS OF LONG SHANK MACHINE TAPS.
36 - A3 TAP SCREW THREAD LIMITS.
36 - A4 LONG SHANK MACHINE TAPS OVER 24 mm DIAMETER.
39 - APPENDIX B - EXTENDED TOLERANCE SYSTEM FOR TAPS
39 - B1 GENERAL.
39 - B2 BASIS OF THE SYSTEM.
39 - B3 TAP CLASSES.
40 - B4 PITCH DIAMETER TOLERANCE.
41 - B5 MAJOR DIAMETER.
44 - APPENDIX C - RECOMMENDED SIZES FOR TAPPING DRILLS
44 - C1 GENERAL.
45 - C2 RECOMMENDED DIMENSIONS FOR TAPPING DRILLS.
51 - APPENDIX D - GENERAL DIMENSIONS AND BASIS FOR THE DERIVATION OF TOLERANCES FOR MACHINE AND HAND TAP BLANKS (INCLUDING THOSE F
51 - D1 GENERAL.
51 - D2 NOMINAL DIMENSIONS.
51 - D3 MANUFACTURING TOLERANCES.

Specifies taps for cutting ISO metric general purpose screw threads in both fine and coarse pitch series. It covers materials, properties, and basic design details for taps of diameter 1 to 64 mm; the diameter/pitch combinations are in agreement with AS 1721 and AS 1725. The ISO tolerance system for the threaded limits is adopted except that the tolerance increments have been additionally applied to the major diameter in order to ensure assembly of coated products. Tap blanks are the same as those given in ISO/R529 and ISO 2283.

This standard applies to taps for cutting ISO metric screw threads. It includes standard machine taps and hand taps with ground threads and also taps with cut threads, and covers diameters from 1 mm up to and including 64 mm in both coarse and fine pitch series. The diameter/pitch combinations are in agreement with AS 1275* and AS 1721. General dimensions, tolerances, and deviations for the threaded portion, types of taps, and other main features are specified, but the details of design are left to the manufacturer. If specific design features are required these need to be specified by the purchaser at the time of his enquiry or order. Taps for the tapping of nut threads are not specified in this standard owing to the many varieties in existence.Cut thread taps are specified for metric coarse pitch screw threads only, and one tolerance class is specified.The general dimensions of long shank machine taps, and tapping drill sizes for use with fluted taps are also included in appendices.NOTE: To ensure interchangeability of machine taps in related holders, the blank dimensions given in Supplement 1 for inch screwing taps are the same as those specified in this standard for metric threads.

Reconfirmed 1987