Since 1 955
UNC Unified National Coarse
METRIC (I.S.O.) Nominal dia. mm.
Pitch (P) mm.
Tap drill sizes mm.
M2.0 M2.0 M2.2 M2.2 M2.5 M2.5 M3.0 M3.0 M3.5 M3.5 M4.0 M4.0 M4.5 M4.5 M5.0 M5.0 M6.0 M6.0 M7.0 M7.0 M8.0 M8.0 M8.0 M9.0 M9.0 M9.0 *M10.0 M10.0 M10.0 M11.0 M11.0 M12.0 *M12.0 M12.0 M12.0 M14.0 *M14.0 M14.0 M14.0 M16.0 Ø M16.0 M16.0 M18.0 *M18.0 M18.0 M18.0 M20.0 Ø M20.0 M20.0 M20.0 M22.0 M22.0 M22.0 M22.0 M24.0 M24.0 M24.0 M24.0 Ø M25.0 M25.0 M27.0 M27.0 M28.0 M30.0 M30.0 Ø M32.0 M33.0 M33.0 M36.0 M36.0 M39.0 M39.0 Ø M40.0 M40.0 M42.0 M42.0 M45.0 M45.0 M48.0 M48.0 M52.0 M52.0 M56.0 M56.0 M60.0 M60.0
0.25 0.40 0.25 0.45 0.35 0.45 0.35 0.50 0.35 0.60 0.50 0.70 0.50 0.75 0.50 0.80 0.75 1.00 0.75 1.00 0.75 1.00 1.25 0.75 1.00 1.25 1.00 1.25 1.50 1.00 1.50 1.00 1.25 1.50 1.75 1.00 1.25 1.50 2.00 1.00 1.50 2.00 1.00 1.50 2.00 2.50 1.00 1.50 2.00 2.50 1.00 1.50 2.00 2.50 1.00 1.50 2.00 3.00 1.50 2.00 1.50 3.00 1.50 1.50 3.50 1.50 2.00 3.50 3.00 4.00 3.00 4.00 1.50 3.00 4.00 4.50 4.00 4.50 4.00 5.00 4.00 5.00 4.00 5.50 4.00 5.50
1.75 1.60 1.96 1.75 2.15 2.05 2.65 2.50 3.15 2.90 3.50 3.30 4.00 3.70 4.50 4.20 5.20 5.00 6.20 6.00 7.20 7.00 6.80 8.20 8.00 7.80 9.00 8.80 8.50 10.00 9.50 11.00 10.80 10.50 10.20 13.00 12.80 12.50 12.00 15.00 14.50 14.00 17.00 16.50 16.00 15.50 19.00 18.50 18.00 17.50 21.00 20.50 20.00 19.50 23.00 22.50 22.00 21.00 23.50 23.00 25.50 24.00 26.50 28.50 26.50 30.50 31.00 29.50 33.00 32.00 36.00 35.00 38.50 37.00 38.00 37.50 41.00 40.50 44.00 43.00 48.00 47.00 52.00 50.50 56.00 54.50
*SPARK PLUG PITCHES
Nominal dia.
Threads per inch 64 56 48 40 40 32 32 24 24 40 32 24 24 20 18 16 14 13 12 11 11 10 10 9 8 7 7 6 6 5 4.5
No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 No. 8 No. 10 No. 12 1/8” 5/32” 3/16” 7/32” 1/4” 5/16” 3/8” 7/16” 1/2” 9/16” 5/8” 11/16” 3/4” 13/16” 7/8” 1” 1.1/8” 1.1/4” 1.3/8” 1.1/2” 1.3/4” 2”
UNF Unified National Fine
Tap drill sizes mm. 1.55 1.85 2.10 2.35 2.65 2.85 3.50 3.90 4.50 2.65 3.30 3.80 4.60 5.10 6.60 8.00 9.40 10.80 12.20 13.50 15.25 16.50 18.00 19.50 22.25 25.00 28.00 30.75 34.00 39.50 45.00
Nominal dia.
Threads per inch 80 72 64 56 48 44 40 36 32 28 40 32 32 32 28 24 24 20 20 18 18 16 16 16 14 14 12 12 12 12 12
No. 0 No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 No. 8 No. 10 No. 12 1/8” 5/32” 3/16” 7/32” 1/4” 5/16” 3/8” 7/16” 1/2” 9/16” 5/8” 11/16” 13/16” 3/4” 7/8” 1” 1” 1.1/8” 1.1/4” 1.3/8” 1.1/2”
Tap drill sizes mm. 1.25 1.55 1.90 2.15 1.40 1.70 1.95 3.50 4.10 4.70 2.65 3.30 4.10 4.90 5.50 6.90 8.50 9.90 11.50 12.90 14.50 16.00 17.50 17.50 20.40 23.50 23.25 26.50 29.50 32.75 36.00
BSPT (Rc) British Standard Pipe Taper Nominal dia.
BSW British Standard Whitworth Nominal dia.
Threads per
Tap drill sizes
1/16” 3/32” 1/8” 5/32” 3/16” 7/32” 1/4” 5/16” 3/8” 7/16” 1/2” 9/16” 5/8” 11/16” 3/4” 7/8” 1” 1.1/8” 1.1/4” 1.1/2” 1.3/4” 2”
inch 60 48 40 32 24 24 20 18 16 14 12 12 11 11 10 9 8 7 7 6 5 4.5
mm. 1.20 1.90 2.55 3.20 3.70 4.50 5.10 6.50 7.90 9.30 10.50 12.10 13.50 15.00 16.25 19.25 22.00 24.75 28.00 33.50 39.00 44.50
Threads per inch
Tap drill sizes mm.
No. 0
1.00
5.10
No. 1
0.90
4.50
No. 2
0.81
4.00
No. 3
0.73
3.40
No. 4
0.66
3.00
No. 5
0.59
2.65
No. 6
0.53
2.30
1/8”
Tap drill sizes without Reamer mm. 8.40
1/4”
19
10.80
11.20
No. 7
0.48
2.05
3/8”
19
14.25
14.75
No. 8
0.43
1.80
1.2”
14
17.75
18.25
3/4”
14
23.00
23.75
No. 9
0.39
1.55
1”
11
29.00
30.00
No. 10
0.35
1.40
1.1/4”
11
37.50
38.50
No. 11
0.31
1.20
1.1/2”
11
43.50
44.50
No. 12
0.28
1.05
2”
11
55.00
56.00
No. 13
0.25
0.98
No. 14
0.23
0.80
Nominal dia. 1/8” 1/4” 3/8” 1/2”
Threads per inch 28 19 19 14
Tap drill sizes mm. 8.60 11.50 15.00 18.75
3/4”
14
24.25
1” 1.1/4” 1.1/2”
11 11 11
30.40 39.00 45.00
2”
11
Nominal dia.
Threads per inch 28 19 19 14 14 14 14 11 11 11 11 11
1/8” 1/4” 3/8” 1/2” 5/8” 3/4” 7/8” 1” 1.1/4” 1.1/2” 1.3/4” 2”
56.75
Tap drill sizes mm. 8.80 11.80 15.25 19.00 21.00 24.50 28.25 30.75 39.50 45.00 51.00 57.00
Chisel edge corner
Nominal dia. 1/16” 1/8” 1/4” 3/8” 1/2” 3/4” 1” 1.1/4” 1.1/2” 2”
Threads per inch 27 27 18 18 14 14 11.1/2 11.1/2 11.1/2 11.1/2
Flute
Body
Helix angle
mm. 4.00
7/32”
28
4.60
1/4”
26
5.30
9/32”
26
6.10
5/16”
22
6.80
3/8”
20
8.30
7/16”
18
9.70
1/2”
16
11.10
9/16”
16
12.70
5.8”
14
14.00
11/16”
14
15.50
3/4”
12
16.75
7/8”
11
19.75
1”
10
22.75
1.1/8”
9
25.50
1.1/4”
9
28.50
1.3/8”
8
31.50
1.1/2”
8
34.50
Nominal dia.
Threads Tap per drill sizes inch mm. *1/8” 40 2.55 5/32” 40 3.20 3/16” 40 3.95 7/32” 40 4.75 1/4” 40 5.50 9/32” 32 6.10 5/16” 32 7.00 3/8” 32 8.60 *1/8” ME Tape is identical to 1/8” BSW
Nominal dia.
Threads Tap per drill sizes inch mm. *1/4” 26 5.30 5/16” 26 6.90 3/8” 26 8.40 7/16” 26 10.00 1/2” 26 11.50 5/8” 26 14.70 3/4” 26 17.75 7/8” 26 21.10 1” 26 24.75 *1/4” Brass is identical to 1/4” BSF
Tap drill sizes with without Reamer Reamer 6.10 6.30 8.40 8.70 10.70 11.10 14.25 14.50 17.50 18.00 22.75 23.25 28.50 29.00 37.50 38.00 43.50 44.00 55.00 56.00
NPS American National Straight Pipe Nominal dia.
Threads per inch
Tap drill sizes 75% to 80% full thread
1/8”
27
9.00
1/4”
18
11.50
3/8”
18
15.00
1/2”
14
18.50
3/4”
14
23.75
1”
11.1/2
30.00
1.1/4”
11.1/2
39.00
1.1/2”
11.1/2
45.00
Overall length Chamfer (or taper lead) Flute run out
Land
Body Clearance Cutting Edge
Square
Axis of tap
Flute length
Flute Cutting face
Lip length
inch 32
Land
Heel
Shank
Relative lip height
3/16”
TAP NOMENCLATURE
Drill axis
Rake angle (helix angle at periphery)
Tap drill sizes
Brass Thread
NPT (API) American National Pipe Taper
TWIST DRILL NOMENCLATURE
Lip clearance angle
Threads per
ME Model Engineers
Nominal dia.
Tap drill sizes with Reamer mm. 8.00
BSP PI (Rp)
Nominal dia.
BA British Association
Threads per inch 28
BSPF (G) British Standard Pipe Parallel
BSW British Standard Fine
Thread length Flute length
Lead of helix
Shank diameter
Length of square
Overall length
Lip Flank
Point
Thread relief radial
Point angle
Body clearance diameter
Chisel edge Heel
Flank
Diameter Web or core thickness
Depth of body clearance Chisel edge angle
Heel
Face
Straight Cutting Face Positive Rake
Straight Cutting Face Radial Rake
Curved Cutting Face Positive Rake
Outer Corner
Ø CONDUIT PITCHES
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Size of square