Special Threads
Alongside the general-purpose fastening threads (metric, UNC/UNF, BSW/BSF) covered elsewhere on this site, a handful of thread forms are used for specific, specialised applications rather than general clamping. This chart covers dimensional information for PG (a metric electrical conduit thread), electrical bulb/socket threads, buttress threads (an asymmetric form suited to high one-directional axial loads, such as in a screw jack or vice), knuckle threads (a rounded, low-precision form tolerant of dirt and rough handling, often seen on bottle caps and fire hydrant fittings), and threads to DIN 405 and DIN 20400.
Dimensional Charts relating to Pg DIN 40430, METRIC ELECTRICAL, BUTTRESS, KNUCKLE DIN 405 and KNUCKLE DIN 20400 Threads.
Dimensions shown are in mm, if you wish to convert to Inches, please use our universal converter.
PG THREAD DIMENSIONS
The standard, codified by the Deutsches Institut für Normung (DIN, German Institute for Standardization),
is DIN 40430. Panzergewinde sizes are named with the prefix PG plus a nominal
number which approximately corresponds to the maximum cable diameter (in millimeters) that can be passed through the conduit.
The thread is used predomantily to join pieces of electrical conduit and cable glands.
Because the walls of the conduit are usually relatively thin, the thread depth should not be very large.
Thus a thread angle of 80° is used.
The Verband der Elektrotechnik, Elektronik und Informationstechnik (VDE)
(which began as a trade association for standardization in electrical engineering)
originally standardized (and named) the thread for use with conduit and cable glands that were made of steel,
although today the thread is used with both steel (typically plated with combinations of nickel, zinc,
or tin to resist rusting) and polyvinyl chloride (PVC).
Beginning in 2000, the VDE standard for cable glands (VDE 0619) was formally replaced by EN 50262.
After a transitional period of several years during which it could still be used,
it was replaced in 2003 by a final metric fine thread with 1.5mm (0.0591in) pitch.
Similarly, conduit threads were replaced by EN 60423.
| METRIC Pg ELECTRICAL THREAD DIMENSIONS - DIN 40430 | NOMINAL SIZE | THREAD FORM | MAJOR DIAMETER | PITCH | THREADS PER INCH | PITCH DIAMETER | MINOR DIAMETER | THREAD HEIGHT | RADIUS | TAPPING DRILL DIAMETER | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| d=D | p | tpi | d2=D2 | d1 | H1 | mm | mm | ||||
| Pg7 | Pg | 12.5 | 1.27 | 20 | 11.89 | 11.28 | 0.61 | 0.14 | 11.4 | ||
| Pg9 | Pg | 15.2 | 1.411 | 18 | 14.53 | 13.86 | 0.67 | 0.15 | 14 | ||
| Pg11 | Pg | 18.6 | 1.411 | 18 | 17.93 | 17.26 | 0.67 | 0.15 | 17.25 | ||
| Pg13.5 | Pg | 20.4 | 1.411 | 18 | 19.73 | 19.06 | 0.67 | 0.15 | 19 | ||
| Pg16 | Pg | 22.5 | 1.411 | 18 | 21.83 | 21.16 | 0.67 | 0.15 | 21.25 | ||
| Pg21 | Pg | 28.3 | 1.588 | 16 | 27.54 | 26.78 | 0.76 | 0.17 | 26.75 | ||
| Pg29 | Pg | 37 | 1.588 | 16 | 36.24 | 35.48 | 0.76 | 0.17 | 35.5 | ||
| Pg36 | Pg | 47 | 1.588 | 16 | 46.24 | 45.48 | 0.76 | 0.17 | 45.5 | ||
| Pg42 | Pg | 54 | 1.588 | 16 | 53.24 | 52.48 | 0.76 | 0.17 | 52.5 | ||
| Pg48 | Pg | 59.3 | 1.588 | 16 | 58.54 | 57.78 | 0.76 | 0.17 | 57.75 | ||
METRIC ELECTRICAL THREAD DIMENSIONS
| METRIC ELECTRICAL THREAD DIMENSIONS - EN 60423 TABLE 1 | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| NOMINAL SIZE | THREAD FORM TYPE | MAJOR DIAMETER | PITCH | RADIUS | PITCH DIAMETER | MINOR DIAMETER (MALE THREAD) | MINOR DIAMETER (FEMALE THREAD) | THREAD HEIGHT (MALE THREAD) | THREAD HEIGHT (FEMALE THREAD) | TAPPING DRILL DIAMETER (mm) | CLEARANCE DRILL DIAMETER (mm) |
| ISO MF | Type | d=D | P | R | d2=D2 | d3 | D1 | h3 | H1 | ||
| 12x1.5 | M | 12.00 | 1.50 | 0.217 | 11.026 | 10.160 | 10.376 | 0.920 | 0.812 | 10.50 | 12.500 |
| 16x1.5 | M | 16.00 | 1.50 | 0.217 | 15.026 | 14.160 | 14.376 | 0.920 | 0.812 | 14.50 | 16.500 |
| 20x1.5 | M | 20.00 | 1.50 | 0.217 | 19.026 | 18.160 | 18.376 | 0.920 | 0.812 | 18.50 | 20.500 |
| 25x1.5 | M | 25.00 | 1.50 | 0.217 | 24.026 | 23.160 | 23.376 | 0.920 | 0.812 | 23.50 | 25.500 |
| 32x1.5 | M | 32.00 | 1.50 | 0.217 | 31.026 | 30.160 | 30.376 | 0.920 | 0.812 | 30.50 | 32.500 |
| 40x1.5 | M | 40.00 | 1.50 | 0.217 | 39.026 | 38.160 | 38.376 | 0.920 | 0.812 | 38.50 | 40.500 |
| 50x1.5 | M | 50.00 | 1.50 | 0.217 | 49.026 | 48.160 | 48.376 | 0.920 | 0.812 | 48.50 | 50.500 |
| 63x1.5 | M | 63.00 | 1.50 | 0.217 | 62.026 | 61.160 | 61.376 | 0.920 | 0.812 | 61.50 | 63.500 |
| 75x1.5 | M | 75.00 | 1.50 | 0.217 | 74.026 | 73.160 | 73.376 | 0.920 | 0.812 | 73.50 | 75.500 |
| 80x2 | M | 80.00 | 2.00 | 78.00 | 80.50 | ||||||
| 85x2 | M | 85.00 | 2.00 | 83.00 | 85.50 | ||||||
| 90x2 | M | 90.00 | 2.00 | 88.00 | 90.50 | ||||||
| 100x2 | M | 100.00 | 2.00 | 98.00 | 100.50 | ||||||
| 100x3 | M | 100.00 | 3.00 | 97.00 | 100.50 | ||||||
| 110x3 | M | 110.00 | 3.00 | 107.00 | 110.50 | ||||||
BUTTRESS THREAD DIMENSIONS
The buttress thread form, also known as the breech-lock thread form, refers to two different thread profiles.
One is a type of lead-screw and the other is a type of hydraulic sealing thread form.
The lead-screw type is often used in machinery and the sealing type is often used in oil fields.
In oil field tubing, buttress thread is a pipe thread form designed to provide a tight hydraulic seal.
The thread form is similar to that of Acme thread the force is transmitted almost parallel to the axis and
thread is about the same strength as standard v threads.
| BUTTRESS COARSE THREAD - DIN 513 DIMENSIONS | ||||
|---|---|---|---|---|
| NOMINAL DIAMETER | OUTSIDE DIAMETER | PITCH | BOLT THREAD MINOR DIAMETER | TAPPING SIZE DRILL |
| mm | mm | mm | mm | |
| S 10 x 2 | 10.00 | 2.00 | 6,528 | 7,000 |
| S 12 x 3 | 12.00 | 3.00 | 6,794 | 7,500 |
| S 14 x 3 | 14.00 | 3.00 | 8,794 | 9,500 |
| S 16 x 4 | 16.00 | 4.00 | 9,058 | 10,000 |
| S 18 x 4 | 18.00 | 4.00 | 11,058 | 12,000 |
| S 20 x 4 | 20.00 | 4.00 | 13,058 | 14,000 |
| S 22 x 5 | 22.00 | 5.00 | 13,322 | 14,500 |
| S 24 x 5 | 24.00 | 5.00 | 15,322 | 16,500 |
| S 26 x 5 | 26.00 | 5.00 | 17,322 | 18,500 |
| S 28 x 5 | 28.00 | 5.00 | 19,322 | 20,500 |
| S 30 x 6 | 30.00 | 6.00 | 19,586 | 21,000 |
| S 32 x 6 | 32.00 | 6.00 | 21,586 | 23,000 |
| S 34 x 6 | 34.00 | 6.00 | 23,586 | 25,000 |
| S 36 x 6 | 36.00 | 6.00 | 25,586 | 27,000 |
| S 38 x 7 | 38.00 | 7.00 | 25,852 | 27,500 |
| S 40 x 7 | 40.00 | 7.00 | 27,825 | 29,500 |
| S 42 x 7 | 42.00 | 7.00 | 39,825 | 31,500 |
| S 44 x 7 | 44.00 | 7.00 | 31,825 | 33,500 |
| S 46 x 8 | 46.00 | 8.00 | 32,116 | 34,000 |
| S 48 x 8 | 48.00 | 8.00 | 34,116 | 36,000 |
| S 50 x 8 | 50.00 | 8.00 | 36,116 | 38,000 |
| S 52 x 8 | 52.00 | 8.00 | 38,116 | 40,000 |
| S 55 x 9 | 55.00 | 9.00 | 39,380 | 41,500 |
| S 60 x 9 | 60.00 | 9.00 | 44,380 | 46,500 |
| S 65 x 10 | 65.00 | 10.00 | 47,644 | 50,000 |
| S 70 x 10 | 70.00 | 10.00 | 52,644 | 55,000 |
| S 75 x 10 | 75.00 | 10.00 | 57,644 | 60,00 |
| S 80 x 10 | 80.00 | 10.00 | 62,644 | 65,000 |
| S 85 x 12 | 85.00 | 12.00 | 64,174 | 67,000 |
| S 90 x 12 | 90.00 | 12.00 | 69,174 | 72,000 |
| S 95 x 12 | 95.00 | 12.00 | 74,174 | 77,000 |
| S 100 x 12 | 100.00 | 12.00 | 79,174 | 82,000 |
KNUCKLE THREAD DIMENSIONS
Knuckle threads are insensitive to dirt and damage due to their round shape.
They can be used as fastening screw threads in clutch or brake spindles of railway cars as well as for large valves and gates.
These threads are also used in electric bulb and bottles etc.
| KNUCKLE THREAD DIN 405 DIMENSIONS | |||||
|---|---|---|---|---|---|
| THREAD SIZE | NOMINAL DIAMETER | BOLT THREAD MINOR DIAMETER | NUT THREAD MINOR DIAMETER | PITCH | TPI |
| mm | mm | mm | mm | ||
| Rd 8 x 1/10" | 8,254 | 5,460 | 5,714 | 2,540 | 10 |
| Rd 9 x 1/10" | 9,254 | 6,460 | 6,714 | 2,540 | 10 |
| Rd 10 x 1/10" | 10,254 | 7,460 | 7,714 | 2,540 | 10 |
| Rd 11 x 1/10" | 11,254 | 8,460 | 8,714 | 2,540 | 10 |
| Rd 12 x 1/10" | 12,254 | 9,460 | 9,714 | 2,540 | 10 |
| Rd 14 x 1/8" | 14,318 | 10,825 | 11,142 | 3,175 | 8 |
| Rd 16 x 1/8" | 16,318 | 4,166 | 12,825 | 3,175 | 8 |
| Rd 18 x 1/8" | 18,318 | 14,825 | 15,142 | 3,175 | 8 |
| Rd 20 x 1/8" | 20,318 | 16,825 | 17,142 | 3,175 | 8 |
| Rd 22 x 1/8" | 22,318 | 18,825 | 19,142 | 3,175 | 8 |
| Rd 24 x 1/8" | 24,318 | 20,825 | 21,142 | 3,175 | 8 |
| Rd 28 x 1/8" | 28,318 | 24,825 | 25,142 | 3,175 | 8 |
| Rd 30 x 1/8" | 30,318 | 26,825 | 27,142 | 3,175 | 8 |
| Rd 32 x 1/8" | 32,318 | 28,825 | 29,142 | 3,175 | 8 |
| Rd 34 x 1/8" | 34,318 | 30,825 | 31,142 | 3,175 | 8 |
| Rd 36 x 1/8" | 36,318 | 32,825 | 33,142 | 3,175 | 8 |
| Rd 38 x 1/8" | 38,318 | 34,825 | 35,142 | 3,175 | 8 |
| Rd 40 x 1/16" | 40,423 | 35,767 | 36,190 | 4,233 | 6 |
| Rd 42 x 1/16" | 42,423 | 37,767 | 38,190 | 4,233 | 6 |
| Rd 44 x 1/16" | 44,423 | 39,767 | 40,190 | 4,233 | 6 |
| Rd 46 x 1/16" | 46,423 | 41,767 | 42,190 | 4,233 | 6 |
| Rd 48 x 1/16" | 48,423 | 43,767 | 44,190 | 4,233 | 6 |
| Rd 50 x 1/16" | 50,423 | 45,767 | 46,190 | 4,233 | 6 |
| Rd 52 x 1/16" | 52,423 | 47,767 | 48,100 | 4,233 | 6 |
| Rd 55 x 1/16" | 55,423 | 50,767 | 51,190 | 4,233 | 6 |
| Rd 58 x 1/16" | 58,423 | 53,767 | 54,190 | 4,233 | 6 |
| Rd 60 x 1/16" | 60,423 | 55,767 | 56,190 | 4,233 | 6 |
| Rd 62 x 1/16" | 62,423 | 57,767 | 58,190 | 4,233 | 6 |
| Rd 65 x 1/16" | 65,423 | 60,767 | 61,190 | 4,233 | 6 |
| Rd 68 x 1/16" | 68,423 | 63,767 | 64,190 | 4,233 | 6 |
| Rd 70 x 1/16" | 70,423 | 65,767 | 66,190 | 4,233 | 6 |
| Rd 72 x 1/16" | 72,423 | 67,767 | 68,190 | 4,233 | 6 |
| Rd 75 x 1/16" | 75,423 | 70,767 | 71,190 | 4,233 | 6 |
| Rd 78 x 1/16" | 78,423 | 73,767 | 74,190 | 4,233 | 6 |
| Rd 80 x 1/16" | 80,423 | 75,767 | 76,190 | 4,233 | 6 |
| Rd 82 x 1/16" | 82,423 | 77,767 | 78,190 | 4,233 | 6 |
| Rd 85 x 1/16" | 85,423 | 80,767 | 81,190 | 4,233 | 6 |
| Rd 88 x 1/16" | 88,423 | 83,767 | 84,190 | 4,233 | 6 |
| Rd 90 x 1/16" | 90,423 | 85,767 | 86,190 | 4,233 | 6 |
| Rd 92 x 1/16" | 92,423 | 87,767 | 88,190 | 4,233 | 6 |
| Rd 95 x 1/16" | 95,423 | 90,767 | 91,190 | 4,233 | 6 |
| Rd 98 x 1/16" | 98,423 | 93,767 | 94,190 | 4,233 | 6 |
| Rd 100 x 1/6" | 100,423 | 95,767 | 96,190 | 4,233 | 6 |
| Rd 105 x 1/4" | 105,635 | 98,650 | 99,285 | 6,350 | 4 |
| Rd 110 x 1/4" | 110,635 | 103,650 | 104,285 | 6,350 | 4 |
| Rd 115 x 1/4" | 115,635 | 108,650 | 109,285 | 6,350 | 4 |
| Rd 120 x 1/4" | 120,635 | 113,650 | 114,285 | 6,350 | 4 |
| Rd 120 x 1/4" | 120,635 | 113,650 | 114,285 | 6,350 | 4 |
| Rd 125 x 1/4" | 125,635 | 118,650 | 119,285 | 6,350 | 4 |
| Rd 130 x 1/4" | 130,635 | 123,650 | 124,285 | 6,350 | 4 |
| Rd 135 x 1/4" | 135,635 | 128,650 | 129,285 | 6,350 | 4 |
| Rd 140 x 1/4" | 140,635 | 133,650 | 134,285 | 6,350 | 4 |
| Rd 145 x 1/4" | 145,635 | 138,650 | 139,285 | 6,350 | 4 |
| Rd 150 x 1/4" | 150,635 | 143,650 | 144,285 | 6,350 | 4 |
| Rd 155 x 1/4" | 155,635 | 148,650 | 149,285 | 6,350 | 4 |
| Rd 160 x 1/4" | 160,635 | 153,650 | 154,285 | 6,350 | 4 |
| Rd 165 x 1/4" | 165,635 | 158,650 | 159,285 | 6,350 | 4 |
| Rd 170 x 1/4" | 170,635 | 163,650 | 164,285 | 6,350 | 4 |
| Rd 175 x 1/4" | 175,635 | 168,650 | 169,285 | 6,350 | 4 |
| Rd 180 x 1/4" | 180,635 | 173,650 | 174,285 | 6,350 | 4 |
| Rd 185 x 1/4" | 185,635 | 178,650 | 179,285 | 6,350 | 4 |
| Rd 190 x 1/4" | 190,635 | 183,650 | 184,285 | 6,350 | 4 |
| Rd 195 x 1/4" | 195,635 | 188,650 | 189,285 | 6,350 | 4 |
| Rd 200 x 1/4" | 200,635 | 193,650 | 194,285 | 6,350 | 4 |
| KNUCKLE THREAD DIN 20400 DIMENSIONS | |||||||
|---|---|---|---|---|---|---|---|
| THREAD SIZE | MAJOR DIAMETER | PITCH DIAMETER | MINOR DIAMETER | TAPPING DRILL | |||
| MIN | MAX | MIN | MAX | MIN | MAX | ||
| Rd10x3 | 10.3 | 10.54 | 8.5 | 8.74 | 7 | 7.24 | 7,000 |
| Rd12x3 | 12.3 | 12.54 | 11 | 10.74 | 9 | 9.24 | 9,000 |
| Rd14x3 | 14.3 | 14.54 | 13 | 12.74 | 11 | 11.24 | 11,000 |
| Rd16x4 | 16.4 | 16.72 | 14 | 14.32 | 12 | 12.32 | 12,000 |
| Rd18x4 | 18.4 | 18.72 | 16 | 16.32 | 14 | 14.32 | 14,000 |
| Rd02x4 | 20.4 | 20.72 | 18 | 18.32 | 16 | 16.32 | 16,000 |
| Rd22x4 | 22.4 | 22.72 | 20 | 20.32 | 18 | 18.32 | 18,000 |
| Rd25x4 | 25.4 | 25.72 | 23 | 23.32 | 21 | 21.32 | 21,000 |
| Rd28x4 | 28.4 | 28.72 | 26 | 26.32 | 24 | 24.32 | 24,000 |
| Rd32x4 | 32.4 | 32.72 | 30 | 30.32 | 28 | 28.32 | 28,000 |
| Rd36x5 | 36.5 | 36.9 | 34 | 33.9 | 31 | 31.4 | 31,000 |
| Rd40x5 | 40.5 | 40.9 | 38 | 37.9 | 35 | 35.4 | 35,000 |
| Rd42x5 | 42.5 | 42.9 | 40 | 39.9 | 37 | 37.4 | 37,000 |
| Rd45x5 | 45.5 | 45.9 | 43 | 42.9 | 40 | 40.4 | 40,000 |
| Rd48x5 | 48.5 | 48.9 | 46 | 45.9 | 43 | 43.4 | 43,000 |
| Rd50x5 | 50.5 | 50.9 | 48 | 47.9 | 45 | 45.4 | 45,000 |
| Rd53x5 | 53.5 | 53.9 | 51 | 50.9 | 48 | 48.4 | 48,000 |
| Rd56x5 | 56.5 | 56.9 | 54 | 53.9 | 51 | 51.4 | 51,000 |
| Rd60x6 | 60.6 | 61.08 | 57 | 57.48 | 54 | 54.48 | 54,000 |
| Rd63x6 | 63.6 | 64.08 | 60 | 60.48 | 57 | 57.48 | 57,000 |
| Rd67x6 | 67.6 | 68.08 | 64 | 64.48 | 61 | 61.48 | 61,000 |
| Rd70x6 | 704 | 71.08 | 67 | 67.48 | 54 | 64.48 | 64,000 |
| Rd75x6 | 75.6 | 76.08 | 72 | 72.48 | 69 | 69.48 | 69,000 |
| Rd80x6 | 80.6 | 81.08 | 77 | 77.48 | 74 | 74.48 | 74,000 |
| Rd85x6 | 85.6 | 86.08 | 82 | 82.48 | 79 | 79.48 | 79,000 |
| Rd90x8 | 90.8 | 91.44 | 86 | 86.64 | 82 | 82.64 | 82,000 |
| Rd95x8 | 95.8 | 96.44 | 91 | 91.64 | 87 | 87.64 | 87,000 |
| Rd100x8 | 101 | 101.4 | 96 | 96.64 | 92 | 92.64 | 92,000 |
| Rd106x8 | 107 | 107.4 | 102 | 102.6 | 98 | 98.64 | 98,000 |
| Rd112x8 | 113 | 113.4 | 108 | 108.6 | 104 | 104.6 | 104,000 |
| Rd118x8 | 119 | 119.4 | 114 | 114.6 | 110 | 110.6 | 110,000 |
| Rd125x8 | 126 | 126.4 | 121 | 121.6 | 117 | 117.6 | 117,000 |
| Rd132x10 | 133 | 133.8 | 127 | 127.8 | 122 | 122.8 | 122,000 |
| Rd140x10 | 141 | 141.8 | 135 | 135.8 | 130 | 130.8 | 130,000 |
| Rd150x10 | 151 | 151.8 | 145 | 145.8 | 140 | 140.8 | 140,000 |
| Rd160x10 | 161 | 161.8 | 155 | 155.8 | 150 | 150.8 | 150,000 |
| Rd170x10 | 171 | 171.8 | 165 | 165.8 | 160 | 160.8 | 160,000 |
| Rd180x12 | 181 | 182.2 | 174 | 176 | 168 | 169 | 168,000 |
| Rd190x12 | 191 | 192.2 | 184 | 185 | 178 | 179 | 178,000 |
| Rd200x12 | 201 | 202.16 | 194 | 195 | 188 | 189 | 188,000 |
| Rd212x12 | 213 | 214.2 | 206 | 207 | 200 | 201 | 200,000 |
| Rd224x12 | 225 | 226.2 | 218 | 219 | 212 | 213 | 212,000 |
| Rd236x16 | 238 | 238.9 | 228 | 229.3 | 220 | 221.3 | 220,000 |
| Rd250x16 | 252 | 252.9 | 242 | 243.3 | 234 | 235.3 | 234,000 |
| Rd265x16 | 267 | 267.9 | 257 | 258.3 | 249 | 250.3 | 249,000 |
| Rd280x16 | 282 | 282.9 | 272 | 273.3 | 264 | 265.3 | 264,000 |
| Rd300x16 | 302 | 302.9 | 292 | 293.3 | 284 | 285.3 | 284,000 |
RELATED PAGES
FREQUENTLY ASKED QUESTIONS
What is a buttress thread used for?
Buttress threads have one steep, near-perpendicular flank and one shallow flank, making them efficient at carrying high axial load in a single direction — typical uses include screw jacks, vices, and other linear-motion mechanisms that only need to push or pull one way.
What is a knuckle thread and why is it rounded?
A knuckle thread has a rounded crest and root rather than a sharp V or trapezoidal form, making it tolerant of dirt, rough handling, and repeated quick engagement/disengagement — common applications include light bulb bases, bottle caps, and some fire hose couplings.
What is a PG thread?
PG (Panzergewinde, German for "armoured thread") is a thread form historically used for electrical conduit and cable gland fittings in Europe, distinct from the metric fastening thread of the same nominal size.
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