M56 × 5.5 M profile External Thread Specifications
M56x5.5-6g
ASMESTD: ASME B1.13MSOURCE: Table 14 · p. 30TYPE: External (bolt/screw)CLASS: 6gSERIES: M coarse (Table 4)1st choice (Table 6, p. 10) · standard size
Major diameter
55.925 – 55.365
max – min
Pitch diameter
52.353 – 52.088
max – min
Minor diameter
49.971 – 48.700
max – min (min is a reference value)
Fundamental deviation
es −0.075
pitch 5.5 mm · position g
Thread profile
M56x5.5-6g: solid line = maximum material profile, dashed = minimum material, hatched = tolerance zone (Figs. 8 and 9), grey dashed = basic profile (Fig. 1). Drawn to scale; values in mm, diameters shortened.
Limits of size, class 6g
| Dimension | Basic | Max | Min | Tolerance |
|---|---|---|---|---|
| Major diameter dOutside diameter over the crests | 56.000 | 55.925 | 55.365 | 0.560 |
| Pitch diameter d2Where thread and groove widths are equal; sets the fit | 52.428 | 52.353 | 52.088 | 0.265 |
| Minor diameter, flat root d1Max d1 (flat form); min = d3 of the rounded form, for reference | 50.046 | 49.971 | 48.700ref. | 1.271ref. |
| Rounded-form minor diameter d3d3 max and d3 min; used for tools and gaging | 49.728ref. | 48.700ref. | ||
| Deviations, pitch diameter es / eiUpper and lower deviation from the basic pitch diameter (Fig. 4) | — | −0.075 | −0.340 | — |
| Deviations, major diameter es / eiCrest diameter | — | −0.075 | −0.635 | — |
Dimensions in millimetres. Values are those of the standard (ASME B1.13M); calculated cells follow the standard’s formulas. Where the standard prints a value that differs from its formula, the printed value is shown with a note.
Tolerance zones relative to the basic size, mm (Fig. 4)
Lead, flank angle and length of engagement
- Allowable lead variation ±δP
- 0.076 mmOver the length of engagement
- Equivalent change in functional diameter δd2
- 0.132 mmHalf the pitch diameter toleranceformula gives 0.133
- Allowable half-angle variation ±δα
- 0° 55′ Each 30° flank angle
- Length of engagement, normal LE
- 28.0 – 85.0 mmShort up to / long over: see all values
Lead source: Table 17, p. 49; half-angle source: Table 18; length of engagement: Table 7
Notes
- Table 17 prints lead 0.076 / functional dia 0.132; para 10.1.5 with the PD tolerance 0.265 gives 0.076 / 0.133. The printed value is the round-half-to-even result (rounding rule used before ASME B1.30, Foreword (d)(4)). Normal tolerance, small allowance (para 5.5.1(a)); the usual bolt class, ~ inch 2A.
Mates
M56x5.5-6g screws into a thread of the same standard at the same size and pitch. The standard mating internal thread is class 6H. Check the fit with the standard pair →
Working out the mating options…
Different pitch or a different thread family never mate; the fit check runs over both tolerance zones.
Related thread sizes
Same diameter other pitch, and neighbouring sizes
All values for M56x5.5-6gevery column of the workbook row
| Designation | M56x5.5-6g |
|---|---|
| Alternate designation (all capitals, para 7.2.3) | M56X5.5-6G EXT |
| Pitch in designation | 5.5 |
| Thread form | M |
| Series | Coarse |
| Series name | Standard coarse pitch series (Table 4) |
| External / internal | External |
| Class | 6g |
| Nominal size | M56 |
| Pitch P (mm) | 5.50 |
| Basic major dia D, d (mm) | 56.000 |
| Size category | 1st choice (Table 6, p. 10) · standard size |
| Source table | Table 14 |
| Printed page | 30 |
| Thread type | M coarse (Table 4) |
| Tolerance position, pitch dia | g |
| Tolerance grade, pitch dia | 6 |
| Tolerance position, crest dia | g |
| Tolerance grade, crest dia | 6 |
| Fundamental deviation es / EI, pitch dia (mm) | -0.075 |
| Fundamental deviation es / EI, crest dia (mm) | -0.075 |
| Allowance |es| / EI (mm) | 0.075 |
| Major dia max (mm) | 55.925 |
| Major dia min (mm) | 55.365 |
| Major dia tolerance Td (mm) | 0.560 |
| Major dia status | Toleranced (d max, d min) |
| Basic pitch dia D2, d2 (mm) | 52.428 |
| Pitch dia max (mm) | 52.353 |
| Pitch dia min (mm) | 52.088 |
| PD tolerance Td2 / TD2 (mm) | 0.265 |
| Basic minor dia D1, d1 (mm) | 50.046 |
| Minor dia max (mm) | 49.971 |
| Minor dia min (mm) | 48.700 |
| Minor dia tolerance TD1 (mm) | 1.271 |
| Minor dia status | d1 max toleranced (flat form, para 9.3.2(e)); min is d3 min of the rounded form, for reference (Table 14 note 4) |
| Max minor dia, flat form d1 (mm) | 49.971 |
| Min minor dia, rounded form d3 (mm, reference) | 48.700 |
| Max minor dia, rounded form d3, para 9.3.2(f) (mm) | 49.728 |
| Upper deviation, pitch dia es / ES (mm) | -0.075 |
| Lower deviation, pitch dia ei / EI (mm) | -0.340 |
| Upper deviation, crest dia (mm) | -0.075 |
| Lower deviation, crest dia (mm) | -0.635 |
| LE short, up to (mm) | 28.0 |
| LE normal, over (mm) | 28.0 |
| LE normal, up to and incl. (mm) | 85.0 |
| LE long, over (mm) | 85.0 |
| LE source | Table 7 |
| Lead variation ± (mm) | 0.076 |
| Equivalent change in functional dia (mm) | 0.132 |
| Lead values source | Table 17, p. 49 |
| Half-angle variation ± | 0° 55′ |
| Half-angle source | Table 18 |
| Lead angle at basic PD (deg) | 1.9125 |
| Lead angle (deg min) | 1° 55′ |
| Tensile stress area As (mm²) | 2030.020 |
| Thread angle (deg) | 60 |
| Flank angle (deg) | 30 |
| Sharp V height H (mm) | 4.763140 |
| Thread height h = 5H/8 (mm) | 2.976962 |
| Crest flat (mm) | 0.687500 |
| Root flat (mm) | 1.375000 |
| Sweep cut: start diameter (mm) | 55.925000 |
| Sweep cut: tip diameter (mm) | 49.971000 |
| Sweep cut: depth (mm) | 2.977000 |
| Sweep cut: profile width at start diameter (mm) | 4.812500 |
| Crest flat as modelled (mm) | 0.687705 |
| Inch (App. C): allowance (in.) | 0.00295 |
| Inch (App. C): major dia max (in.) | 2.20177 |
| Inch (App. C): major dia min (in.) | 2.17972 |
| Inch (App. C): pitch dia max (in.) | 2.06114 |
| Inch (App. C): pitch dia min (in.) | 2.05071 |
| Inch (App. C): PD tolerance (in.) | 0.01043 |
| Inch (App. C): minor dia max (in.) | 1.96736 |
| Inch (App. C): d3 min / D max, reference (in.) | 1.91732 |
| Inch (App. C): pitch (in.) | 0.21654 |
| Inch (App. C): printed page | 58 |
| Check against formulas | OK: all 8 printed Table 14 values agree with the formulas. Table 17 differs: printed 0.076 / 0.132, formula 0.076 / 0.133 |
| Notes | Table 17 prints lead 0.076 / functional dia 0.132; para 10.1.5 with the PD tolerance 0.265 gives 0.076 / 0.133. The printed value is the round-half-to-even result (rounding rule used before ASME B1.30, Foreword (d)(4)). Normal tolerance, small allowance (para 5.5.1(a)); the usual bolt class, ~ inch 2A. |
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ASME B1.13M: Metric Screw Threads: M Profile. Source: workbook data (2026-10-10). Confirm against your licensed copy of the standard before use.