# Nylon-insert lock nuts, inch (ASME B18.16.6): 1/4 to 1-1/2 width across flats, across corners, height

> What are the dimensions of a 1/4-20 or 3/8-16 nylon insert lock nut (nylock), and what wrench size does it take?

- Category: Hardware › Fasteners
- Kind: Standard part
- Basis: fasten.it's ASME B18.16.6 (2008) Table 1, inch series; numbers only
- Page: https://xemstudio.com/objects/nylon-insert-lock-nuts-inch-asme-b18-16-6/ · JSON: https://xemstudio.com/api/geometry?object=nylon-insert-lock-nuts-inch-asme-b18-16-6 · Plain text: https://xemstudio.com/objects/nylon-insert-lock-nuts-inch-asme-b18-16-6/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files CC BY 4.0 or their publisher's license
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**Exact dimensions.** True size, with no tolerance added.

## Notes

- Columns (inches unless stated): threads per inch for coarse (UNC) and fine (UNF) series; B max, C min, D min, E min as the page prints them without defining the letters. B max is the hex width: for 1/4 it is 0.44 in, the 7/16 in (0.4375) across-flats of a 1/4-20 hex nut on hex-nuts-inch, and C min (0.488 for 1/4) is a bit under the across-corners of a 7/16 hex (0.505), so B is read as width across flats and C as across corners. D min (0.298 for 1/4) and E min (0.225) are read as overall height and a lower height of the hex part, but the page does not say so; check the standard before relying on D and E.
- The mm column is the nominal size. The 'overall height' of a nylon-insert nut (including the collar) is the number a pocket depth needs; check the maker's drawing for the nut you buy. No file: the collar profile is not published as numbers on the page read, and the hex-prism part is the same as hex-nuts-inch.
- Metric nyloc nuts (ISO 7040, DIN 985): nylon-insert-lock-nuts-iso-7040-din-985 and nyloc-nuts-metric. McMaster-Carr sells thin, regular and heavy nylon-insert locknuts with per-part STEP; its category is linked, not copied.

## Sizes

| size (in) | nominal (mm) | UNC TPI | UNF TPI | B max (in) | B max (mm) | C min (in) | D min (in) | E min (in) |
|---|---|---|---|---|---|---|---|---|
| 1/4 | 6.35 | 20 | 28 | 0.440 | 11.18 | 0.488 | 0.298 | 0.225 |
| 5/16 | 7.94 | 18 | 24 | 0.500 | 12.70 | 0.557 | 0.329 | 0.250 |
| 3/8 | 9.53 | 16 | 24 | 0.560 | 14.22 | 0.628 | 0.438 | 0.335 |
| 7/16 | 11.11 | 14 | 20 | 0.627 | 15.93 | 0.698 | 0.438 | 0.324 |
| 1/2 | 12.7 | 13 | 20 | 0.750 | 19.05 | 0.840 | 0.579 | 0.464 |
| 9/16 | 14.29 | 12 | 18 | 0.877 | 22.28 | 0.980 | 0.626 | 0.469 |
| 5/8 | 15.88 | 11 | 18 | 0.940 | 23.88 | 1.050 | 0.735 | 0.593 |
| 3/4 | 19.05 | 10 | 16 | 1.060 | 26.92 | 1.190 | 0.860 | 0.742 |
| 7/8 | 22.23 | 9 | 14 | 1.250 | 31.75 | 1.400 | 0.969 | 0.790 |
| 1 | 25.4 | 8 | 12 | 1.440 | 36.58 | 1.619 | 1.016 | 0.825 |
| 1-1/8 | 28.58 | 7 | 12 | 1.627 | 41.33 | 1.830 | 1.141 | 0.930 |
| 1-1/4 | 31.75 | 7 | 12 | 1.815 | 46.10 | 2.046 | 1.360 | 1.125 |
| 1-3/8 | 34.93 | 6 | 12 | 2.000 | 50.80 | 2.259 | 1.547 | 1.282 |
| 1-1/2 | 38.1 | 6 | 12 | 2.197 | 55.80 | 2.470 | 1.578 | 1.313 |

## Where the files are

- fasten.it: [ASME B18.16.6 nylon insert lock nuts, inch series (2008) Table 1: B max, C min, D min, E min; 1/4 to 1-1/2](https://www.fasten.it/norms/norm/asme_b18.16.6) — web — Reference page; numbers only. The page does not define the column letters
- McMaster-Carr: [Locknuts (nylon-insert, thin and heavy profiles) (free STEP/IGES per part, for your own design use; no redistribution)](https://www.mcmaster.com/products/locknuts/hex-nut-profile~thin-heavy/) — STEP, IGES, PDF — McMaster-Carr site terms: personal design use, no redistribution (verify at link)

## Questions

**What wrench size is a 3/8-16 nylock nut?**

B max is 0.56 in (9/16 in) in the ASME B18.16.6 table at fasten.it, matching the 9/16 in hex nut on hex-nuts-inch.

**How tall is a 1/4-20 nylon insert lock nut?**

The table's D min is 0.298 in and E min 0.225 in; the page does not define the letters, so check the standard.

## Fits with

- [Hex nuts, inch: #4-40 to 3/4-10 (ASME B18.2.2)](https://xemstudio.com/objects/hex-nuts-inch/)
- [Nylon-insert lock nuts (nyloc), ISO 7040 and DIN 985, M3–M36: width across flats, height, bearing diameter + M10–M30 envelope files](https://xemstudio.com/objects/nylon-insert-lock-nuts-iso-7040-din-985/)
- [Nyloc lock nuts, M2.5–M8 (DIN 985)](https://xemstudio.com/objects/nyloc-nuts-metric/)
- [Flat washers, inch: SAE and USS, 1/4 to 3/4 in (ASME B18.21.1 Type A)](https://xemstudio.com/objects/flat-washers-inch/)
- [Plain washers, inch Type B (narrow, regular, wide): #0 to 3 in ID, OD, thickness + 12 washer files](https://xemstudio.com/objects/plain-washers-inch-type-b/)