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Fine Thread Nylon Insert Lock Nut Dimensions (ISO 10512, M8 to M36)

Guide · Updated October 28, 2026

ISO 10512 covers prevailing torque hexagon regular nuts with a non-metallic (nylon) insert and metric fine pitch thread, no flange. Height is the ISO 8673 style 1 m min plus the insert. Values come from the ISO 10512:2012 preview table, checked against the globalfastener ISO 10512 table (s, e, h, m) and our ISO 7040 chart, which shares the same hex, heights, corners and bearing face. All agree on every value shown; mw matches our ISO 10513 chart. Not shown: da, and the non-preferred M14x1.5, to match our other fine pitch lock nut charts. Sources list M36 pitch as 3 mm in the globalfastener table and ISO 8673; the preview text extraction was unclear, so check the pitch on the label.

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Step by step

  1. Confirm fine pitch: ISO 10512 is fine pitch: M8x1, M10x1.25, M12x1.5, M16x1.5, M20x1.5, M24x2. For coarse thread use ISO 7040.
  2. Pick the wrench: Same hex as ISO 7040 and ISO 8673: M8 13 mm, M10 16 mm, M12 18 mm, M16 24 mm, M20 30 mm, M24 36 mm.
  3. Use total height for length: h max includes the nylon ring: M8 9.50 mm, M12 14.90 mm, M20 22.80 mm.
  4. Check thread height: m min is the metal thread length, same as an ISO 8673 nut: M12 10.37 mm.
  5. Leave thread past the nut: Run at least 2 full threads past the top of the nylon ring so the insert grips.
  6. Keep it cool: The nylon insert is for service up to about 120 C. For hot spots use the all-metal ISO 10513 nut.

ISO 10512 fine thread nylon insert lock nut dimensions (mm)

Columns: thread size x pitch (first pitch preferred), width across flats s max and min (s max is the wrench size), total height h max and min, thread height m min, wrenching height mw min, width across corners e min, bearing face diameter dw min.

Worked example: bolt length for an M12x1.5 nylon lock nut

Grip 20 mm, washer 2.5 mm, nut h max 14.90 mm, plus 2 threads at 1.5 mm = 3 mm. Total 40.4 mm, so an M12x1.5 x 45 works.

Common problems

FAQ

What is the difference between ISO 10512 and ISO 7040?

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Both are regular nylon insert hex lock nuts with no flange and the same hex and heights. ISO 7040 is coarse thread (M12x1.75); ISO 10512 is fine pitch (M12x1.5 or M12x1.25).

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What is the difference between ISO 10512 and ISO 10513?

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ISO 10513 is the all-metal fine pitch lock nut. It is lower (M12 h max 12.30 mm vs 14.90 mm) and handles heat better. ISO 10512 uses a nylon ring and is gentler on threads.

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What is the difference between ISO 10512 and ISO 12125?

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ISO 12125 is a fine pitch nylon insert lock nut with a built-in flange. ISO 10512 has no flange, so add a washer if you need load spread.

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Is ISO 10512 strong enough?

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The standard itself notes fine pitch regular nuts have a higher chance of thread stripping and points to high nuts where that matters. Match the nut class to the bolt.

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What wrench fits an M16x1.5 nylon lock nut?

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24 mm.

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Can I reuse a nylon insert lock nut?

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Prevailing torque drops each time. Replace nuts on critical joints.

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General shop information only — follow your drawing, tool maker's data and your quality system.