1/4-20- TAP
- #7 · .2010″
- CLOSE
- 17/64″
- G5 DRY
- 8.5 ft·lb / 11 N·m
Q-01
Bench labels · frequent coarse threads
75% CUT TAP · CLOSE CLEARANCE · GENERALIZED DRY TORQUEOrder of operations: identify with a pitch gauge → confirm diameter → select cutting or forming tap → drill → gauge the thread → verify the fastener grade → use the application/OEM torque when one exists. Generalized torque below assumes an adequate steel nut or fully verified internal thread.
5/16-18- TAP
- F · .2570″
- CLOSE
- 21/64″
- G5 DRY
- 17.4 ft·lb / 24 N·m
3/8-16- TAP
- 5/16″ · .3125″
- CLOSE
- 25/64″
- G5 DRY
- 30.9 ft·lb / 42 N·m
1/2-13- TAP
- 27/64″ · .4219″
- CLOSE
- 17/32″
- G5 DRY
- 75.4 ft·lb / 102 N·m
M6×1.0- TAP
- 5.0 mm
- CLOSE
- 6.4 mm
- 8.8 DRY
- 10.5 N·m / 7.7 ft·lb
M8×1.25- TAP
- 6.8 mm
- CLOSE
- 8.4 mm
- 8.8 DRY
- 25.5 N·m / 18.8 ft·lb
M10×1.5- TAP
- 8.5 mm
- CLOSE
- 10.5 mm
- 8.8 DRY
- 50.5 N·m / 37.2 ft·lb
M12×1.75- TAP
- 10.3 mm
- CLOSE
- 13.0 mm
- 8.8 DRY
- 88 N·m / 64.9 ft·lb
Tap values use Guhring's cut-tap formula and nearest common drill. Torque uses 75% of proof load with K=.20; friction and joint limits can override it completely.
S-10
Unified inch cutting-tap & clearance schedule
ASME B1.1-2024 · ASME B18.2.8-1999 (S2021)S-10 / UNC + UNFINCHES · CUT TAPS · THEORETICAL THREAD %32 ROWS
| Thread | TPI | Major Ø | 75% drill | 55% relief drill | Close clearance | Loose clearance | Series |
|---|---|---|---|---|---|---|---|
#4-40 UNC | 40 | 0.1120 | #43 · 0.0890 | 3/32 · 0.0938 | #31 · .120 | #27 · .144 | Preferred |
#4-48 UNF | 48 | 0.1120 | #42 · 0.0935 | #40 · 0.0980 | #31 · .120 | #27 · .144 | Fine |
#5-40 UNC | 40 | 0.1250 | #38 · 0.1015 | #36 · 0.1065 | #28 · .141 | #17 · .173 | Preferred |
#5-44 UNF | 44 | 0.1250 | #37 · 0.1040 | 7/64 · 0.1094 | #28 · .141 | #17 · .173 | Fine |
#6-32 UNC | 32 | 0.1380 | #36 · 0.1065 | #32 · 0.1160 | #23 · .154 | #13 · .185 | Preferred |
#6-40 UNF | 40 | 0.1380 | #33 · 0.1130 | #31 · 0.1200 | #23 · .154 | #13 · .185 | Fine |
#8-32 UNC | 32 | 0.1640 | #29 · 0.1360 | 9/64 · 0.1406 | #15 · .180 | #3 · .213 | Preferred |
#8-36 UNF | 36 | 0.1640 | #29 · 0.1360 | #27 · 0.1440 | #15 · .180 | #3 · .213 | Fine |
#10-24 UNC | 24 | 0.1900 | #25 · 0.1495 | #20 · 0.1610 | #5 · .206 | B · .238 | Preferred |
#10-32 UNF | 32 | 0.1900 | #21 · 0.1590 | #19 · 0.1660 | #5 · .206 | B · .238 | Fine |
#12-24 UNC | 24 | 0.2160 | #16 · 0.1770 | #13 · 0.1850 | — | — | Preferred |
#12-28 UNF | 28 | 0.2160 | #14 · 0.1820 | #11 · 0.1910 | — | — | Fine |
1/4-20 UNC | 20 | 0.2500 | #7 · 0.2010 | #3 · 0.2130 | 17/64 · .266 | 19/64 · .297 | Preferred |
1/4-28 UNF | 28 | 0.2500 | #3 · 0.2130 | #2 · 0.2210 | 17/64 · .266 | 19/64 · .297 | Fine |
5/16-18 UNC | 18 | 0.3125 | F · 0.2570 | I · 0.2720 | 21/64 · .328 | 23/64 · .359 | Preferred |
5/16-24 UNF | 24 | 0.3125 | I · 0.2720 | 9/32 · 0.2812 | 21/64 · .328 | 23/64 · .359 | Fine |
3/8-16 UNC | 16 | 0.3750 | 5/16 · 0.3125 | Q · 0.3320 | 25/64 · .391 | 27/64 · .422 | Preferred |
3/8-24 UNF | 24 | 0.3750 | Q · 0.3320 | 11/32 · 0.3438 | 25/64 · .391 | 27/64 · .422 | Fine |
7/16-14 UNC | 14 | 0.4375 | U · 0.3680 | W · 0.3860 | 29/64 · .453 | 31/64 · .484 | Preferred |
7/16-20 UNF | 20 | 0.4375 | 25/64 · 0.3906 | Y · 0.4040 | 29/64 · .453 | 31/64 · .484 | Fine |
1/2-13 UNC | 13 | 0.5000 | 27/64 · 0.4219 | 7/16 · 0.4375 | 17/32 · .531 | 39/64 · .609 | Preferred |
1/2-20 UNF | 20 | 0.5000 | 29/64 · 0.4531 | 15/32 · 0.4688 | 17/32 · .531 | 39/64 · .609 | Fine |
9/16-12 UNC | 12 | 0.5625 | 31/64 · 0.4844 | 1/2 · 0.5000 | — | — | Preferred |
9/16-18 UNF | 18 | 0.5625 | 33/64 · 0.5156 | 33/64 · 0.5156 | — | — | Fine |
5/8-11 UNC | 11 | 0.6250 | 17/32 · 0.5312 | 9/16 · 0.5625 | 21/32 · .656 | 47/64 · .734 | Preferred |
5/8-18 UNF | 18 | 0.6250 | 37/64 · 0.5781 | 37/64 · 0.5781 | 21/32 · .656 | 47/64 · .734 | Fine |
3/4-10 UNC | 10 | 0.7500 | 21/32 · 0.6562 | 43/64 · 0.6719 | 25/32 · .781 | 29/32 · .906 | Preferred |
3/4-16 UNF | 16 | 0.7500 | 11/16 · 0.6875 | 45/64 · 0.7031 | 25/32 · .781 | 29/32 · .906 | Fine |
7/8-9 UNC | 9 | 0.8750 | 49/64 · 0.7656 | 51/64 · 0.7969 | 29/32 · .906 | 1 1/32 · 1.031 | Preferred |
7/8-14 UNF | 14 | 0.8750 | 13/16 · 0.8125 | 53/64 · 0.8281 | 29/32 · .906 | 1 1/32 · 1.031 | Fine |
1-8 UNC | 8 | 1.0000 | 7/8 · 0.8750 | 29/32 · 0.9062 | 1 1/32 · 1.031 | 1 5/32 · 1.156 | Preferred |
1-12 UNF | 12 | 1.0000 | 59/64 · 0.9219 | 15/16 · 0.9375 | 1 1/32 · 1.031 | 1 5/32 · 1.156 | Fine |
75% and 55% columns are nearest stocked drills to Guhring's theoretical formula: drill = basic major Ø − (0.01299 × desired %)/TPI. Guhring recommends 60–70% for most applications; the 55% relief column is a lower-load option for difficult materials, not an automatic “hard steel” rule. #12 and 9/16 clearance sizes are absent from B18.2.8: specify the fit on the drawing instead of borrowing an adjacent row. Actual thread percentage falls with drill runout.
S-20
ISO metric cutting-tap & clearance schedule
ISO 261:1998 · ISO 262:2023 · ISO 965-1:2026 · ISO 273 / B18.2.8S-20 / M + MFMILLIMETRES · CUT TAPS · TARGET → STOCK DRILL30 ROWS
| Thread | Pitch | Major Ø | 75% target → drill | 55% target → drill | Close clearance | Loose clearance | Series |
|---|---|---|---|---|---|---|---|
M2×0.4 | 0.4 | 2 | 1.61 → 1.6 | 1.71 → 1.7 | 2.2 | 2.6 | Coarse |
M2.5×0.45 | 0.45 | 2.5 | 2.06 → 2.1 | 2.18 → 2.2 | 2.7 | 3.1 | Coarse |
M3×0.5 | 0.5 | 3 | 2.51 → 2.5 | 2.64 → 2.6 | 3.2 | 3.6 | Coarse |
M3×0.35 | 0.35 | 3 | 2.66 → 2.7 | 2.75 → 2.7 | 3.2 | 3.6 | Fine |
M4×0.7 | 0.7 | 4 | 3.32 → 3.3 | 3.50 → 3.5 | 4.3 | 4.8 | Coarse |
M4×0.5 | 0.5 | 4 | 3.51 → 3.5 | 3.64 → 3.6 | 4.3 | 4.8 | Fine |
M5×0.8 | 0.8 | 5 | 4.22 → 4.2 | 4.43 → 4.4 | 5.3 | 5.8 | Coarse |
M5×0.5 | 0.5 | 5 | 4.51 → 4.5 | 4.64 → 4.6 | 5.3 | 5.8 | Fine |
M6×1 | 1 | 6 | 5.03 → 5.0 | 5.29 → 5.3 | 6.4 | 7 | Coarse |
M6×0.75 | 0.75 | 6 | 5.27 → 5.3 | 5.46 → 5.5 | 6.4 | 7 | Fine |
M8×1.25 | 1.25 | 8 | 6.78 → 6.8 | 7.11 → 7.1 | 8.4 | 10 | Coarse |
M8×1 | 1 | 8 | 7.03 → 7.0 | 7.29 → 7.3 | 8.4 | 10 | Fine |
M10×1.5 | 1.5 | 10 | 8.54 → 8.5 | 8.93 → 8.9 | 10.5 | 12 | Coarse |
M10×1.25 | 1.25 | 10 | 8.78 → 8.8 | 9.11 → 9.1 | 10.5 | 12 | Fine |
M10×1 | 1 | 10 | 9.03 → 9.0 | 9.29 → 9.3 | 10.5 | 12 | Fine |
M12×1.75 | 1.75 | 12 | 10.30 → 10.3 | 10.75 → 10.7 | 13 | 14.5 | Coarse |
M12×1.5 | 1.5 | 12 | 10.54 → 10.5 | 10.93 → 10.9 | 13 | 14.5 | Fine |
M12×1.25 | 1.25 | 12 | 10.78 → 10.8 | 11.11 → 11.1 | 13 | 14.5 | Fine |
M14×2 | 2 | 14 | 12.05 → 12.1 | 12.57 → 12.6 | 15 | 16.5 | Coarse |
M14×1.5 | 1.5 | 14 | 12.54 → 12.5 | 12.93 → 12.9 | 15 | 16.5 | Fine |
M16×2 | 2 | 16 | 14.05 → 14.1 | 14.57 → 14.6 | 17 | 18.5 | Coarse |
M16×1.5 | 1.5 | 16 | 14.54 → 14.5 | 14.93 → 14.9 | 17 | 18.5 | Fine |
M18×2.5 | 2.5 | 18 | 15.56 → 15.6 | 16.21 → 16.2 | 19 | 21 | Coarse |
M18×1.5 | 1.5 | 18 | 16.54 → 16.5 | 16.93 → 16.9 | 19 | 21 | Fine |
M20×2.5 | 2.5 | 20 | 17.56 → 17.6 | 18.21 → 18.2 | 21 | 24 | Coarse |
M20×1.5 | 1.5 | 20 | 18.54 → 18.5 | 18.93 → 18.9 | 21 | 24 | Fine |
M22×2.5 | 2.5 | 22 | 19.56 → 19.6 | 20.21 → 20.2 | 23 | 26 | Coarse |
M22×1.5 | 1.5 | 22 | 20.54 → 20.5 | 20.93 → 20.9 | 23 | 26 | Fine |
M24×3 | 3 | 24 | 21.08 → 21.1 | 21.86 → 21.9 | 25 | 28 | Coarse |
M24×2 | 2 | 24 | 22.05 → 22.1 | 22.57 → 22.6 | 25 | 28 | Fine |
Metric cut-tap formula: drill mm = basic major Ø − (% × pitch)/76.98. The familiar major Ø − pitch shortcut lands near 77% theoretical thread, not exactly 75%. Form/roll taps displace material and require a larger, manufacturer-specified hole (approximately major Ø − pitch/2); never use this cutting-tap table for a forming tap. Clearance is independent of pitch.
P-30
Bolt-head specimen plate · identify before torque
MARKING + STRENGTH · COLOUR IS NOT A GRADEP-31 / PROPERTY TABLEROOM-TEMPERATURE MINIMA · VERIFY SIZE RANGE11 ROWS
| Class / standard | Head mark | Proof or yield min | Tensile min | Typical role | Do not substitute when… |
|---|---|---|---|---|---|
| SAE Grade 2 · J429 | No radial lines* | 55 ksi proof, 1/4–3/4″ | 74 ksi | Light-duty, low-carbon fastener | A joint calls for quenched/tempered Grade 5 or 8. |
| SAE Grade 5 · J429 | 3 radial lines | 85 ksi proof, 1/4–1″ | 120 ksi | General automotive/machinery | Grade 8 preload or structural-bolt geometry is required. |
| SAE Grade 8 · J429 | 6 radial lines | 120 ksi proof | 150 ksi | High-strength machinery | A ductile lower grade, stainless, or structural assembly is specified. |
| F3125 Grade A325 | A325 | 92 ksi yield, 1/2–1″ | 120 ksi | Heavy-hex structural joint | A general cap screw or a non-RCSC joint is expected. |
| F3125 Grade A490 | A490 | 130 ksi yield | 150 ksi | High-strength structural joint | Coating, nut, washer, pretension and installation method are not qualified together. |
| ISO property 4.6 | 4.6 | 225 MPa proof | 400 MPa | Low-strength metric fastener | 8.8-class preload is assumed. |
| ISO property 8.8 | 8.8 | 580 MPa proof ≤M16; 600 MPa >M16 | 800 MPa | General high-tensile metric fastener | Corrosion resistance or class 10.9/12.9 preload is required. |
| ISO property 10.9 | 10.9 | 830 MPa proof | 1,000 MPa | High-load machinery/automotive | The female thread or bearing surface cannot carry its preload. |
| ISO property 12.9 | 12.9 | 970 MPa proof | 1,200 MPa | Socket screws/high stress | Toughness, hydrogen risk or soft parent material governs. |
| ISO 3506 A2-70 | A2-70 | 450 MPa Rp0.2 | 700 MPa | General austenitic stainless | Grade 8 / 10.9 strength is needed; stainless also galls readily. |
| ISO 3506 A4-80 | A4-80 | 600 MPa Rp0.2 | 800 MPa | Higher-strength molybdenum stainless | Class 10.9 strength or a specific corrosion alloy is required. |
*SAE J429 permits no grade mark for Grade 1/2; an unmarked unknown fastener must not be assumed to be a verified Grade 2. Values are standards minima for the stated common ranges, not measured properties of an unknown bolt.
S-40
Generalized torque schedules · friction controls preload
CALCULATED, NOT OEM · 75% PROOF LOAD · MATCH KT = K × F × d
Use this schedule when
A noncritical steel fastener has a verified grade, an adequate steel nut/thread, ordinary bearing surfaces and no application-specific value.
Do not use it when
OEM/service data, structural-bolting procedure, pressure boundary, wheel/engine/brake/aircraft joint, locking nut running torque, gasket seating, adhesive qualification or an engineered preload exists.
Soft parent material
There is no universal “aluminium torque factor.” Calculate internal-thread stripping and bearing capacity from alloy, engagement and geometry; reduce preload or add a qualified insert. Plastic joints need supplier joint tests because creep dominates.
Anti-seize and threadlocker
Both change friction. Anti-seize is a lubricant; a dry torque can over-preload the bolt. A liquid locker may lubricate during assembly. Use the compound/fastener supplier's tested K or torque–tension data.
S-41 / INCH COARSE75% SAE J429 PROOF · K=.20 / .17 / .1520 GRADE ROWS
| Thread | Grade | Stress area in² | Dry K=.20 | Zinc-plated K=.17 | Lubricated K=.15 | Limit before use |
|---|---|---|---|---|---|---|
1/4-20 | SAE 5 | .0318 | 8.5 ft·lb / 11 N·m | 7.2 / 10 | 6.3 / 9 | Verify female thread and head bearing area. |
1/4-20 | SAE 8 | .0318 | 11.9 / 16 | 10.1 / 14 | 8.9 / 12 | |
5/16-18 | SAE 5 | .0524 | 17.4 / 24 | 14.8 / 20 | 13.1 / 18 | General steel nut; no locking-nut drag included. |
5/16-18 | SAE 8 | .0524 | 24.6 / 33 | 20.9 / 28 | 18.4 / 25 | |
3/8-16 | SAE 5 | .0775 | 30.9 / 42 | 26.2 / 36 | 23.2 / 31 | Do not transfer to a gasketed/OEM joint. |
3/8-16 | SAE 8 | .0775 | 43.6 / 59 | 37.0 / 50 | 32.7 / 44 | |
7/16-14 | SAE 5 | .1063 | 49.4 / 67 | 42.0 / 57 | 37.1 / 50 | Check joint separation and embedment. |
7/16-14 | SAE 8 | .1063 | 69.8 / 95 | 59.3 / 80 | 52.3 / 71 | |
1/2-13 | SAE 5 | .1419 | 75.4 / 102 | 64.1 / 87 | 56.5 / 77 | Not an F3125 structural-bolt procedure. |
1/2-13 | SAE 8 | .1419 | 106.4 / 144 | 90.5 / 123 | 79.8 / 108 | |
5/8-11 | SAE 5 | .2260 | 150.1 / 203 | 127.6 / 173 | 112.6 / 153 | Confirm wrench range and calibration. |
5/8-11 | SAE 8 | .2260 | 211.9 / 287 | 180.1 / 244 | 158.9 / 215 | |
3/4-10 | SAE 5 | .3345 | 266.5 / 361 | 226.5 / 307 | 199.9 / 271 | Verify nut grade; plain low-grade nuts can strip. |
3/4-10 | SAE 8 | .3345 | 376.3 / 510 | 319.8 / 434 | 282.2 / 383 | |
7/8-9 | SAE 5 | .4617 | 429.3 / 582 | 364.9 / 495 | 322.0 / 437 | Large joints warrant direct tension control. |
7/8-9 | SAE 8 | .4617 | 606.0 / 822 | 515.1 / 698 | 454.5 / 616 | |
1-8 | SAE 5 | .6057 | 643.6 / 873 | 547.1 / 742 | 482.7 / 654 | Reaction fixture and operator safety govern. |
1-8 | SAE 8 | .6057 | 908.6 / 1232 | 772.3 / 1047 | 681.5 / 924 | |
1-12 | SAE 5 | .6630 | 704.5 / 955 | 598.8 / 812 | 528.4 / 716 | Fine thread raises stress area; do not copy coarse value. |
1-12 | SAE 8 | .6630 | 994.6 / 1348 | 845.4 / 1146 | 745.9 / 1011 |
Calculation: At=.7854(d−.9743/n)²; F=.75×proof stress×At; T=KFd. Grade 5 proof is 85 ksi through 1″; Grade 8 is 120 ksi. Rounded values are a transparent preload model, not measured torque specifications.
S-42 / METRIC COARSE75% ISO 898-1 PROOF · K=.20 / .17 / .1520 CLASS ROWS
| Thread | Class | Stress area mm² | Dry K=.20 | Zinc-plated K=.17 | Lubricated K=.15 | Limit before use |
|---|---|---|---|---|---|---|
M5×0.8 | 8.8 | 14.2 | 6.2 N·m / 4.6 ft·lb | 5.2 / 3.9 | 4.6 / 3.4 | Small fastener: use an in·lb/N·m tool in range. |
M5×0.8 | 10.9 | 14.2 | 8.8 / 6.5 | 7.5 / 5.5 | 6.6 / 4.9 | |
M6×1.0 | 8.8 | 20.1 | 10.5 / 7.7 | 8.9 / 6.6 | 7.9 / 5.8 | Verify tapped-aluminium capacity before class 10.9. |
M6×1.0 | 10.9 | 20.1 | 15.0 / 11.1 | 12.8 / 9.4 | 11.3 / 8.3 | |
M8×1.25 | 8.8 | 36.6 | 25.5 / 18.8 | 21.7 / 16.0 | 19.1 / 14.1 | Legacy OEM values may assume a defined oil. |
M8×1.25 | 10.9 | 36.6 | 36.5 / 26.9 | 31.0 / 22.9 | 27.3 / 20.2 | |
M10×1.5 | 8.8 | 58.0 | 50.5 / 37.2 | 42.9 / 31.6 | 37.8 / 27.9 | Modern ISO hex head is often 16 mm, legacy DIN 17 mm. |
M10×1.5 | 10.9 | 58.0 | 72.2 / 53.2 | 61.4 / 45.3 | 54.1 / 39.9 | |
M12×1.75 | 8.8 | 84.3 | 88.0 / 64.9 | 74.8 / 55.2 | 66.0 / 48.7 | Do not substitute for wheel/engine procedure. |
M12×1.75 | 10.9 | 84.3 | 125.9 / 92.9 | 107.0 / 78.9 | 94.4 / 69.6 | |
M14×2.0 | 8.8 | 115.4 | 140.6 / 103.7 | 119.5 / 88.1 | 105.5 / 77.8 | Confirm 21 vs legacy 22 mm head before tooling. |
M14×2.0 | 10.9 | 115.4 | 201.2 / 148.4 | 171.0 / 126.1 | 150.9 / 111.3 | |
M16×2.0 | 8.8 | 156.7 | 218.1 / 160.8 | 185.4 / 136.7 | 163.6 / 120.6 | Proof stress changes above M16 for class 8.8. |
M16×2.0 | 10.9 | 156.7 | 312.1 / 230.2 | 265.3 / 195.7 | 234.1 / 172.6 | |
M20×2.5 | 8.8 | 244.8 | 440.6 / 325.0 | 374.5 / 276.2 | 330.5 / 243.7 | Class 8.8 proof basis here is 600 MPa. |
M20×2.5 | 10.9 | 244.8 | 609.5 / 449.6 | 518.1 / 382.1 | 457.2 / 337.2 | |
M22×2.5 | 8.8 | 303.4 | 600.7 / 443.1 | 510.6 / 376.6 | 450.5 / 332.3 | Check the actual head/nut series; M22 is less common. |
M22×2.5 | 10.9 | 303.4 | 831.0 / 612.9 | 706.4 / 521.0 | 623.3 / 459.7 | |
M24×3.0 | 8.8 | 352.5 | 761.4 / 561.6 | 647.2 / 477.3 | 571.1 / 421.2 | At this load, direct tension control is preferable. |
M24×3.0 | 10.9 | 352.5 | 1053.3 / 776.9 | 895.3 / 660.3 | 790.0 / 582.6 |
Calculation: As=π/4(d−.9382p)²; F=.75×proof stress×As; T=KFd. K=.17 zinc is a published Fastenal model value; waxed prevailing-torque zinc hardware may vary K=.12–.18, so the supplier's lot data wins. Add prevailing torque separately only when the locking-fastener procedure says to.
D-50
Threaded-joint cutaway · the female thread can fail first
ENGAGEMENT IS A CALCULATION · NOT “1×D ALWAYS”D-51 / STARTING ENGAGEMENTBOSSARD TRIAL VALUES · M6–M16 · 6g/6HVERIFY VDI 2230
| Parent thread | Material strength | 8.8 coarse | 10.9 coarse | 12.9 coarse | Decision |
|---|---|---|---|---|---|
| Heat-treated steel | Rm >800 MPa | 0.8d | 0.9d | 0.9d | Calculate if wall is thin or cyclic. |
| Structural/mild steel | Rm >360 MPa | 1.0d | 1.25d | 1.4d | Insert if full depth or edge distance is unavailable. |
| Grey cast iron GJL-250 | Rm >220 MPa | 1.0d | 1.25d | 1.4d | Mind brittle breakout and wall thickness. |
| Al alloy, stronger | Rm >330 MPa | 1.4d | 1.6d | 2.0d | Use a qualified insert for repeated service/high preload. |
| Al alloy, softer | Rm >180 MPa | 2.0d | 2.5d | — | Do not apply the steel-nut torque table blindly. |
| Thermoplastic | Grade/temperature dependent | Supplier test | Supplier test | Not default | Use a plastic-specific screw or insert; design for creep. |
These are starting values, not a universal minimum. Bossard notes that engagement above 1.5d can jam at tolerance extremes and exact values require VDI 2230. For a repeated-service aluminium or plastic joint, an insert often converts a weak/wearing internal thread into a controlled steel thread.
S-60
Thread lockers, sealants, anti-seize & washers
PRODUCT DATA VERIFIED 2026-09-01 · COLOUR NEVER STANDS ALONE222LOW · PURPLESmall fasteners; removable
243MEDIUM · BLUEGeneral, oil-tolerant
263HIGH · REDPrimerless; heat removal
277HIGH · REDLarge >1″ bolts
290WICKING · GREENPost-assembly, low viscosity
567SEALANT · WHITECoarse tapered pipe threads
S-61 / HENKEL LOCTITETEST: M10 STEEL NUT/BOLT UNLESS NOTEDFULL CURE TYP. 24 h
| Product | Function / colour | Fixture time | Breakaway torque | Temperature | Use / do not use |
|---|---|---|---|---|---|
| LOCTITE 222 | Low strength / purple | 20 min | 6 N·m | −55 to 150°C | Fasteners ≤1/4″ (6.35 mm), ordinary hand-tool removal; not a pipe sealant. |
| LOCTITE 243 | Medium / blue | 10 min | ≈26 N·m | −55 to 180°C | General metal, including passive/plated; removable; not “blue = any brand/spec.” |
| LOCTITE 263 | High / red | 10 min | 33 N·m | −55 to 180°C | Permanent locking; localized ≈260°C heat if hand tools cannot remove. |
| LOCTITE 277 | High, viscous / red | 30 min | 32 N·m | −55 to 150°C | Large bolts/studs >25 mm (1″); not the default for serviceable small fasteners. |
| LOCTITE 290 | Wicking medium-high / green | 20 min | 10 N·m | −55 to 150°C | Apply at an assembled nut/bolt junction; very low viscosity; heat may be required. |
| LOCTITE 567 | Pipe sealant / off-white | See TDS/substrate | 12 N·m on M10 steel | −55 to 250°C | Coarse tapered metal pipe threads; not a substitute for a straight-thread seal. |
Anaerobic cure occurs between close metal surfaces without air. Henkel gives typical full cure as 24 h on active steel; stainless, aluminium, zinc/plated surfaces and temperatures below 5°C can cure more slowly and may need the specified activator. Clean as the product TDS directs. Torque within fixture time; cured breakaway torque is not the tightening torque.
Anti-seize = lubricated joint
It changes thread and bearing friction, sometimes dramatically. Never add anti-seize and retain a dry torque unless the application data explicitly tested that compound, finish and lot. Use only a material/temperature-compatible compound where corrosion, galling or service requirements call for it.
Stainless galling
Austenitic stainless threads can cold-weld. Clean threads, correct fit, slower assembly and a qualified lubricant/locker reduce risk; the resulting torque must match the treated condition.
Galvanic pair
An electrically conductive electrolyte plus dissimilar metals can corrode the less noble metal. Coatings, isolation and compatible compound selection are system decisions; “copper anti-seize everywhere” is not one.
S-62 / RETENTION METHODCLAMP, LOCK, OR SEAL?7 ROWS
| Method | What it does | Use when | Do not rely on when |
|---|---|---|---|
| Plain flat washer | Spreads bearing load/protects surface. | Hole/head geometry or surface pressure requires it. | You need anti-rotation; it is not a lock. |
| Split spring washer | Adds friction while edges bite. | Only if the governing design explicitly specifies it. | High transverse vibration or lubricated joints; Nord-Lock Junker tests show loss of clamp load. |
| Wedge-lock pair | Cam angle converts rotation to bolt stretch. | Qualified hard bearing surfaces and transverse vibration. | Soft wood/plastic, very hard nonmarking surfaces, settlement or a plain washer beneath it. |
| Prevailing-torque nut | Adds running torque to resist rotation. | Temperature and reuse rating fit the application. | You forgot to add measured running torque to seating torque. |
| Anaerobic locker | Fills thread clearance and resists loosening. | Clean/qualified metal threads and cure time are available. | Colour alone is the specification or immediate full load is required. |
| Safety wire / tab | Physically limits rotation. | The applicable procedure defines direction and installation. | Clamp load is already lost; locking position is not preload. |
| Torque-to-yield bolt | Uses controlled plastic stretch for clamp consistency. | The OEM gives torque, angle and sequence. | Reuse: Fel-Pro says TTY bolts are single-use; torque-to-angle is not automatically TTY. |
Torque-angle in three lines: (1) clean/lubricate exactly as specified; (2) seat every fastener to the stated base torque and sequence; (3) mark each head, then rotate the stated angle with an angle gauge. Never invent an angle from this page, and never reuse a TTY bolt.
S-70
Wrench fit & tapping technique
6-POINT FOR HIGH LOAD · PITCH GAUGE BEFORE GUESSINGS-71 / HEX ACROSS FLATSCOMMON CAP SCREWS · CHECK ACTUAL HEAD STANDARD22 ROWS
| System | Bolt | Hex A/F | Near-miss / note |
|---|---|---|---|
| Inch | 1/4″ | 7/16″ | 11 mm is .004″ smaller: may not fit. |
| Inch | 5/16″ | 1/2″ | 13 mm is .012″ larger: rounding risk. |
| Inch | 3/8″ | 9/16″ | 14 mm is .011″ smaller. |
| Inch | 7/16″ | 5/8″ | 16 mm is .005″ larger. |
| Inch | 1/2″ | 3/4″ | 19 mm is only .002″ smaller; still use 3/4″. |
| Inch | 9/16″ | 13/16″ | Do not assume bolt size equals socket. |
| Inch | 5/8″ | 15/16″ | 24 mm is .007″ larger. |
| Inch | 3/4″ | 1-1/8″ | Heavy-hex structural heads differ. |
| Inch | 7/8″ | 1-5/16″ | Use impact-rated socket only with impact tool. |
| Inch | 1″ | 1-1/2″ | Verify cap-screw vs heavy-hex form. |
| Metric ISO | M5 | 8 mm | 5/16″ is .062 mm smaller. |
| Metric ISO | M6 | 10 mm | — |
| Metric ISO | M8 | 13 mm | 1/2″ is .300 mm smaller; often will not fit. |
| Metric ISO | M10 | 16 mm | Legacy DIN commonly 17 mm. |
| Metric ISO | M12 | 18 mm | Legacy DIN commonly 19 mm. |
| Metric ISO | M14 | 21 mm | Legacy DIN commonly 22 mm. |
| Metric ISO | M16 | 24 mm | 15/16″ is .188 mm smaller. |
| Metric ISO | M18 | 27 mm | — |
| Metric ISO | M20 | 30 mm | — |
| Metric ISO | M22 | 34 mm | Less common; confirm standard. |
| Metric ISO | M24 | 36 mm | — |
| Structural | 1/2″ A325 | 7/8″ heavy hex | Not the 3/4″ SAE cap-screw head. |
Widths are common current ASME hex cap screw and ISO 4014/4017 series values; old DIN hardware can have larger M10/M12/M14 heads. Seat a 6-point socket fully for high torque or damaged/corroded heads. A 12-point socket is for access or a 12-point fastener, not extra torque capacity.
S-72 / DRILL + TAP PROCEDURESHORT FORM · CUT VS FORM8 OPERATIONS
| Operation | Purpose | Concrete bench move | Failure / when not to use |
|---|---|---|---|
| 1 · Identify | Separate diameter from pitch. | Gauge a .375″ shank at 16 TPI → 3/8-16 UNC, not M10. | Never judge pitch by eye; near pitches can start and then destroy both threads. |
| 2 · Choose tap | Match chip path and hole. | Spiral point pushes chips through; spiral flute pulls chips from a blind hole. | A forming tap needs ductile material and its own larger drill; do not use the cut table. |
| 3 · Drill | Set thread percentage and alignment. | For M8×1.25 cutting tap, start with 6.8 mm and verify actual drilled diameter. | Runout lowers actual %; too-small holes spike tap torque, too-large holes weaken threads. |
| 4 · Chamfer | Start square without raising a burr. | Lightly break the entry edge, keeping enough full threads for engagement. | A deep countersink silently removes effective engagement. |
| 5 · Lubricate | Control friction, heat and welding. | Use the tap maker's fluid for the exact alloy; cast iron is often cut dry. | Wrong fluid can stain aluminium, promote galling or trap abrasive cast-iron dust. |
| 6 · Hand tap | Cut straight and break chips. | IRWIN: after 2–3 forward turns, reverse 1/2–3/4 turn to break the chip; recheck square. | Do not force rising torque. Machine spiral taps follow their programmed cycle, not this hand rhythm. |
| 7 · Clear / depth | Prevent a packed blind hole. | Withdraw, clear chips and verify usable full-thread depth before bottoming. | A bottomed tap or bolt can feel “tight” without clamping the joint. |
| 8 · Gauge | Prove fit before assembly. | Use the specified GO/NO-GO plug gauge or a verified mating part for noncritical work. | “Bolt goes in” does not verify pitch diameter, class or full-depth thread. |
X-80
Common mistakes · correction-pencil layer
STOP CONDITIONS BEFORE A SCRAPPED PARTAt the same indicated torque, lower K raises clamp load. Match the stated condition; this sheet's K=.15 value is 25% below K=.20 dry.
A2-70 has 450 MPa proof versus SAE Grade 8's 120 ksi (≈827 MPa). Corrosion resistance is not a strength upgrade.
Plastic stretch changes length and clamp response. Replace, then follow the exact OEM sequence and angle.
Guhring recommends 60–70% for most applications; use lower engagement only after the female-thread capacity remains adequate.
Snap-on/Norbar cite 5,000 cycles or 12 months as a default. Recheck after a drop/overload; safety-critical procedures may be shorter.
Return a micrometer click wrench to its lowest indicated setting—not below it. Split-beam/electronic designs follow their manual.
Measure diameter and pitch; confirm the standard. A partial turn is not proof of compatibility.
19 mm and 3/4″ are close; 13 mm and 1/2″ are not interchangeable under load. Use a fully seated 6-point socket.
The bolt may survive while aluminium threads strip, plastic creeps, a washer embeds or the bearing face crushes. Check the whole load path.
“Blue” and “red” are conventions, not cross-brand grades. Record product number, lot, surface preparation, cure and temperature.
R-90
Primary standards & manufacturer engineering sources
TABLE NUMBERS TRACE TO THESE BASES · ACCESSED 2026-09-01- ASME B1.1-2024 — unified inch thread forms, series and designations.
- ASME B18.2.8-1999 (S2021) — close, normal and loose clearance-hole classes; stabilized maintenance.
- ISO 261:1998, ISO 262:2023, and ISO 965-1:2026 — metric plans, selected sizes and current tolerances.
- Guhring Tap Drill Sizes — manufacturer cut/form formulas, 55/65/75% drills and runout warning.
- SAE J429:2014 and Bossard J429 engineering table — inch grade markings and mechanical minima.
- ISO 898-1:2013 and Bossard ISO 898 technical data — metric property-class scope, proof and tensile strengths.
- ASTM F3125/F3125M-26 and Portland Bolt F3125 summary — current structural bolt grades, markings and intended use.
- BUMAX / ISO 3506 comparison data — A4-70/A4-80 and carbon-steel mechanical properties.
- NASA RP-1228 Fastener Design Manual — T=KFd, proof-load preload basis, torque scatter, lubrication, corrosion and locking context.
- Fastenal Torque–Tension Reference Guide — published K=.15/.17/.20 models and zinc/wax variability.
- Bossard Thread Engagement Length — manufacturer trial guidance and VDI 2230 calculation boundary.
- Henkel threadlocking guide and the linked 222, 243, 263, 277, 290 and 567 product data pages — cure, strength, torque and temperature data.
- Nord-Lock split-ring test and wedge-lock limits — Junker-test behavior and application exclusions.
- Fel-Pro TTA vs TTY — torque-angle distinction and single-use TTY guidance.
- IRWIN tap instructions — manufacturer hand-tapping chip-break sequence.
- Snap-on torque-wrench care and Norbar calibration guidance — storage, handling, 5,000-cycle/12-month default.