Technical Specifications

MILLING CUTTERS

TECHNICAL SUPPLY CONDITIONS OF "DAGGER SCREWING TAPS"
1. Screwing Taps are normally of the non- serial type taps with straight flutes for RH cutting.
2. Serial Taps, Helical flute taps and special taps are manufactured against specific orders.
3. Intermediate size / diameter if ordered, shall be supplied with the same dimensions on the next bigger diameter.
4. other general requirements are maintained according to IS: 6171 - Technical supply conditions for High-speed Screwing Taps.

5. Hardness:
Cutting portion:760 HV to 900Hv
Driving Square: 320 Hv to maximum Hardness equal to cutting Portion (In case of two Piece construction)
5.1 Chamfer Dimensions:

No. of taps in a set Type of taps chamfer Chamfer angle Length (Approx)
Serial Non-serial
3
For coarse pitch threads
Rougher intermediate Finisher Taper Second Bottoming 5 degree
10 degree
20 degree
8 threads
4 threads
2 to 3 threads
2
(For fine pitch)
Rougher Finisher Tapper Bottoming 7 degree
20 degree
6 threads
2 to 3 threads
1 Nut 2 degree 20 threads

The approximate word indicated in the column heading is not applicable here, as the range has been specified.
5.2 Radial run out when taps are held between centres( T.I.R)

Diameter in mm Radial runout TIR (Micron)
Above Up to and including Taper lead Thread dia Shank dia
- 10 30 30 30
10 18 30 30 30
18 30 35 35 40
30 40 40 35 40
40 - 40 40 40

5.3 Taps are usually supplied with a back taper of 1:1000 maximum and the thread diameters are measured on 2nd or 3rd behind the chamfer angle.
5.4 The major diameter and pitch diameter for serial taps are calculated with the following formulas:-

Number of taps in a set type Major diameter Min. Pitch diameter
Min Max
3 Rougher Intermediate Finisher dB Min - 0.75p
dB Min - 0.35p
dB Min
d2B Min - 0.25p
d2B Min - 0.08p
d2B Min
d2B Max - 0.25p d2B Max - 0.08p
d2B Max
2 Rougher
Finisher
d2B Min - 0.45p
db Min
d2B Min - 0.12
d2B Min
d@B Max - 0.12p
d2B Max

Where
d2B Min = minimum major diameter of finisher tap
d2B Min = minimum pitch diameter of finisher tap
d2B Max = maximum pitch diameter of finisher tap
p = pitch of threads

6. Serial taps can be supplied in sets or individual pieces as required by the purchaser.
7. Taps are normally supplied with tolerance zone 6H. However taps with other tolerance zone are manufactured against specific order. ISO Metric Taps with thread class 4H are used for tapping internal threads of tolerance zones 4H & 5H recommended for close fit.
Taps with thread tolerance class 6H to be used for tapping internal threads of tolerance Zone 4G, 5G & 6H recommended for medium fit. Taps with thread tolerance class 7H to be used for tapping internal threads of tolerance Zone 6G, 7G & 8H recommended for free fit.
8. Tolerance on threaded portion of taps, other than pipe thread taps, are maintained according to IS 6173 Part 1: 1992
Recommended Rake Angle and Cutting Speed for Taps

Material Rake Angle Cutting Speed m/min
Steel up to 50 kg/mm2 Tensile Strength 15-18 7-10
Steel 50-70 kg/mm2 Tensile Strength 12-15 5-8
Steel 70-90 kg/mm2 Tensile Strength 9-12 4-6
Steel (Alloy) 90-100 kg/mm2 Tensile Strength 6-10 2-3
Steel Casting up to 70 kg/mm2 Tensile Strength 12-15 3-5
Malleable Cast iron 6-10 5-8
Cast iron above 200 Be 0-3 2-3
Cast iron soft 3-5 8-10
Stainless steel 10-12 3-5
Brass 0-3 8-10
bronze 6-12 6-8
Copper long Chipped 15-20 8-12
Copper Short Chipped 6-9 8-12
Aluminium 20-25 10-18
Synthetic and plastic material 0-3 3-5

This speed mentioned is recommended speed only. Under favourable and near to ideal working condition , this can be further increased.

CUTTING PARAMETERS IN TAPING & RECOMMENDED CUTTING FLUIDS

The suggested peripheral speed shown in the following table is only starting points which may be varied considerably to suit service conditions.
Tap drill Sizes

Work material Speed 'Vc' Cutting Fluids
Metre/min Ft/min
Aluminium 15-45 50-150 Kerosene & Lard oil or Kerosene 7 Light oil
Aluminium Bronze 6-24 20-80 Soluble Oil
Bakelite 15-30 50-100 Dry
Brass 15-60 50-200 Soluble Oil or Light Base Oil
Cast iron 15-30 50-100 Dry or Soluble Oil
Copper 9-18 30-60 Mineral Oil with lard or Light Base Oil
Fibre 24-27 80-90 Dry
Magnesium 22-60 75-200 Light Base Oil Diluted with 40% - 50% Kerosene.
Malleable Oil 10-18 35-60 Soluble Oil or Sulphur Base Oil
Magnese Bronze 9-18 30-60 Mineral Oil with lard or Light Base Oil.
Monel metal 6-12 20-40 Sulphur base oil
Naval Brass 24-30 80-100 Mineral Oil with lard or Light Base Oil
Phosphor 9-18 30-60 Mineral Oil with lard or Light Base Oil
Plastics:
Thermo-Plastic 15-30 50-100 Dry or Air jet
Thermo - setting 15-30 50-100 Dry or Air Jet
Steels
Free Machining AISI
1100 Series
18-30 60-100 Soluble or Sulphur Base Oil
Low Carbon(up to to 0.25%) 12-24 60-80 Soluble or Sulphur Base Oil
Medium Carbon Annealed(0.3 to 0.6%) 9-18 830-60 Sulphur Base oil
Heat treated (0.3 to 0.6% carbon) 224 - 283 brinell 7-15 25-50 Chlorinated sulphur base oil
Stainless Steel 1.5 - 10 5-35 Chlorinated sulphur base oil
Titanium alloys 3-12 10-40 Chlorinated sulphur base oil
Zinc-Die Castings 18-45 60-150 Kerosene & lard oil

Recommendations for drills for use prior to tapping ISO metric Screw threads (60 degree Thread Angle)

Tap drill Sizes

Nominal diameter mm Pitch mm Drill dia mm
1.00 0.25 0.75
1.10 0.25 0.85
1.20 0.25 0.95
1.40 0.30 1.10
1.60 0.35 1.25
1.80 0.35 1.45
2.00 0.40 1.60
2.20 0.45 1.75
2.50 0.35 2.15
2.50 0.45 2.05
3.00 0.35 2.65
3.00 0.50 2.50
3.50 0.35 3.15
3.50 0.60 2.90
4.00 0.50 3.50
4.00 0.70 3.30
4.50 0.50 4.00
4.50 0.75 3.70
5.00 0.50 4.50
5.00 0.80 4.20
5.50 0.50 5.00
6.00 0.75 5.20
6.00 1.00 5.00
7.00 0.75 6.20
7.00 0.75 6.20
7.00 1.00 6.00
8.00 0.75 7.20
8.00 01.00 7.00
8.00 1.25 6.80
9.00 0.75 8.20
9.00 1.00 8.00
9.00 1.25 7.80
10.00 0.75 9.20
10.00 1.00 9.00
10.00 1.25 8.80
10.00 1.50 8.50
11.00 0.75 10.20
11.00 1.00 10.00
11.00 1.50 9.50
Nominal diameter mm Pitch mm Drill dia mm
12.00 1.00 11.00
12.00 1.25 10.80
12.00 1.50 10.50
12.00 1.75 10.20
14.00 1.00 13.00
14.00 1.25 12.80
14.00 1.50 12.50
14.00 2.00 12.00
15.00 1.00 14.00
15.00 1.50 13.50
16.00 1.00 15.00
16.00 1.50 14.50
16.00 2.00 14.00
17.00 1.00 16.00
17.00 1.50 15.50
18.00 1.00 17.00
18.00 1.50 16.50
18.00 2.00 16.00
18.00 2.50 15.50
20.00 1.00 19.00
20.00 1.50 18.50
20.00 2.00 18.00
20.00 2.50 17.50
20.00 1.00 21.00
22.00 1.50 20.50
22.00 2.00 20.00
22.00 2.50 19.50
24.00 1.00 23.00
24.00 1.50 22.50
24.00 2.00 22.00
24.00 3.00 21.00
25.00 1.00 24.00
25.00 1.50 23.50
25.00 2.00 23.00
26.00 1.50 24.50
27.00 1.00 26.00
27.00 1.50 25.50
27.00 2.00 25.00

ISO metric Screw threads(60degree Thread Angle)

Nominal diameter mm Pitch mm Drill dia mm
27.00 3.00 24.00
28.00 1.00 27.00
28.00 1.50 26.50
28.00 2.00 26.00
30.00 1.00 29.00
30.00 1.50 28.50
30.00 2.00 28.00
30.00 3.00 27.00
30.00 3.50 26.50
32.00 1.50 30.50
32.00 2.00 30.00
33.00 1.50 31.50
33.00 2.00 31.00
33.00 3.50 29.50
35.00 1.50 33.50
36.00 1.50 34.50
36.00 2.00 34.00
36.00 3.00 33.00
36.00 4.00 32.00
38.00 1.50 36.50
39.00 1.50 37.50
39.00 3.00 36.00
39.00 4.00 35.00
40.00 1.50 38.50
40.00 2.00 38.00
40.00 3.00 37.00
Nominal diameter mm Pitch mm Drill dia mm
42.00 1.50 40.50
42.00 2.00 40.00
42.00 3.00 39.00
42.00 4.00 38.00
42.00 4.50 37.50
45.00 1.50 43.50
45.00 2.00 43.00
45.00 3.00 42.00
45.00 4.00 41.00
45.00 4.50 40.50
48.00 1.50 46.50
48.00 2.00 46.00
48.00 3.00 45.00
48.00 4.00 44.00
48.00 5.00 43.00
50.00 1.50 48.50
50.00 2.00 48.00
50.00 3.00 47.00
52.00 1.50 50.50
52.00 2.00 50.00
52.00 3.00 49.00
52.00 4.00 48.00
52.00 5.00 47.00
56.00 5.50 50.50
BSW
BRITISH STD. WHITWORTH
Nominal dia mm TPI Drill dia mm
1/8 40 2.55
3/16 24 3.7
1/4 20 5.1
5/16 18 6.5
3/8 16 7.9
7/16 14 9.3
1/2 12 10.5
9/16 12 12.1
5/8 11 13.5
11/16 11 15
3/4 10 16.25
7/8 9 19.25
1 8 22
1 1/8 7 24.75
1 1/4 7 28
1 1/2 6 33.5
1 3/4 5 39
2 4.5 44.5
2.1/4 4 51.0
2.1/2 4 57.0
2.3/4 3.5 62.14
3 3.5 68.30
BSW
BRITISH STD. FINE
Nominal dia mm TPI Drill dia mm
3/16 32 4
7/32 28 4.6
1/4 26 5.3
9/32 26 6.1
5/16 22 6.8
3/8 20 8.3
7/16 18 9.7
1/2 16 11.1
9/16 16 12.7
5/8 14 14
11/16 14 15.5
3/4 12 16.75
7/8 11 19.75
1 10 22.75
1 1/8 9 25.5
1 1/4 9 28.5
1 3/8 8 31.5
1 1/2 8 34.5
1.5/8 8 37.90
1.3/4 7 41.00
2 7 47.00
2.1/4 6 53.00
2.1/2 6 58.00
2.3/4 6 63.35
3 5 69.50
Designating no. Diameter mm Pitch mm Nearest Drill Size
0 6.0 1.00 5.10
1 5.3 0.90 4.50
2 4.7 0.81 4.00
3 4.1 0.73 3.40
4 3.6 0.66 3.00
5 3.2 0.59 2.65
6 2.8 0.53 2.30

Recommendations for drills for use prior to tapping Screw threads BSP (parallel) and BSP (Taper) Form (55 degree Thread angle)BSP(Parallel)

Nominal diameter inch Thread per inch Nearest drill size
1/8 28 8.80
1/4 19 11.80
3/8 19 15.25
1/2 14 3/4"
5/8 14 53/64"
3/4 14 24.50
7/8 14 28.25
1 11 30.75
1.1/4 11 39.50
1.1/2 11 1.25/32"
1.3/4 11 51.00
2 11 2.1/4"
2.1/4 11 (63.26)
2.1/2 11 (72.73)
2.3/4 11 (79.08)
3 11 (85.43)
3.1/2 11 (97.88)
4 11 (110.58)

Sizes given with in brackets are hole sizes. Corresponding drill sizes are non- standard.

Recommendations for drills for use prior to tapping Screw threads BSP (parallel) and BSP (Taper) Form
(55 degree Thread angle) BSPT(Taper)

Nominal diameter inch Thread per inch Nearest drill size
1/8 28 8.40
1/4 19 11.20
3/8 19 14.75
1/2 14 2.3/32"
3/4 14 15/16"
1 11 30.00
1.1/4 11 38.50
1.1/2 11 44.50
2 11 56.00
2.1/2 11 2.13/16"
3 11 84.35
3 11 84.35"
3.1/2 11 109.42

Recommendations for drills for use prior to tapping Screw threads Parallel) and Taper Pipe

Pipe Threads - taper 'Rc' series(55 degree Thread angle)
Nominal diameter inch Thread per inch Hole Diameter Cylinder mm Hole Diameter Taper mm (Large Dia)
1/8 28 8.3 8.50
1/4 19 11.00 11.40
3/8 19 14.50 14.90
1/2 14 18.10 18.50
3/4 14 23.50 24.00
1 11 29.60 30.10
1.1/4 11 38.10 38.80
1.1/2 11 44.00 44.70
2 11 56.00 56.50
Pipe Threads - taper 'Rc' series(60 degree Thread angle)
Nominal diameter inch Thread per inch Hole Diameter Taper mm
1/8 28 8.60
1/4 19 11.50
3/8 19 15.00
1/2 14 18.50
3/4 14 24.00
1 11 30.25
1.1/4 11 39.00
1.1/2 11 45.00
2 11 56.50
- - -
Pipe Threads - taper 'Rc' series(55 degree Thread angle)
Nominal diameter inch Thread per inch Hole Diameter Cylinder mm Hole Diameter Taper mm (Large Dia)
1/8 28 8.3 8.50
1/4 19 11.00 11.40
3/8 19 14.50 14.90
1/2 14 18.10 18.50
3/4 14 23.50 24.00
1 11 29.60 30.10
1.1/4 11 38.10 38.80
1.1/2 11 44.00 44.70
2 11 56.00 56.50
American National taper Pipe Hand Taps(NPT)
(60 degree Thread angle)
Nominal diameter inch Thread per inch Hole Diameter Taper mm Hole Diameter Taper mm large Dia
1/8 27 8.5 8.70
1/4 18 11.00 11.30
3/8 18 14.40 14.70
1/2 14 17.80 18.20
3/4 14 23.10 23.60
1 11 1/2 29.10 29.60
1.1/4 11/12 37.80 38.50
1.1/2 11 1/2 43.90 44.40
2 11 1/2 43.90 44.40
2 11 1/2 55.90 56.40
Pipe Threads- Parallel 'G' series
(60 degree Thread angle)
Nominal diameter inch Thread per inch Hole Diameter Taper mm
1/8 28 8.80
1/4 18 11.80
3/8 19 15.25
1/2 14 19.00
5/8 14 21.00
3/4 14 24.50
7/8 14 28.25
1 11 30.75
1 1/4 11 39.50
1 1/2 11 45.00
1 3/4 11 51.00
2 11 57.00

Recommendations for Drills
for use prior to tapping Screw thread
UNC and UNF Form
(60 degree thread angle)

UNC
UNIFIED COARSE
Nominal diameter inch Thread per inch Drill Dia mm
No.1 64.00 1.55
No.2 56.00 1.85
No.3 48.00 2.10
No.4 40.00 2.35
No.5 40.00 2.65
No.6 32.00 2.85
No.8 32.00 3.50
No.10 24.00 3.90
No. 12 24.00 4.50
1/4 20.00 5.10
5/16 18.00 6.60
3/8 16.00 8.00
7/16 14.0 9.40
1/2 13.00 10.80
9/16 12.00 12.20
5/8 11.00 13.50
3/4 10.00 16.50
7/8 9.00 19.50
1 8.00 22.25
1 1/8 7.00 25.00
1 1/8 7.00 28.00
1.3/8 6.00 30.75
1 1/2 6.00 34.00
1 3/4 5.00 39.50
2 4.50 45.00
UNF
UNIFIED FIne
Nominal diameter inch Thread per inch Drill Dia mm
No. 0 80 1.25
No. 1 72 1.55
No. 2 64 1.90
No. 3 56 2.15
No. 4 48 2.40
No. 5 44 2.70
No. 6 40 2.95
No. 8 36 3.50
No. 10 32 4.10
No. 12 28 4.70
1/4 28 5.50
5/16 24 6.90
3/8 24 8.50
7/16 20 9.90
1/2 20 11.50
9/16 18 12.90
5/8 18 14.50
3/4 16 17.50
7/8 14 20.40
1 12 23.25
1 1/8 12 26.50
1 1/4 12 29.50
1 3/8 12 32.75
1 1/2 12 36.00
- - -