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DIN 1587 · DIN 917

Hex Cap Nuts Manufacturer in India

A hexagon nut with a closed end that hides and protects the bolt end. We make hex cap nuts to DIN 1587 (high, domed) and DIN 917 (low, crowned) in stainless A2 and A4, steel and brass. Below: the nut in section to scale, both dimension tables, high against low, how long the bolt may be and a finder.

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  • ISO 9001:2015 certified manufacturer
  • High and low types
  • Polished stainless finish
  • EN 10204 3.1 / 3.2
Stainless steel hexagon domed cap nuts
DIN 1587 M4 – M24 DIN 917 M4 – M64 Spanner as ISO 4032
Overview

DIN 1587, DIN 917 Hex Cap Nuts: Manufacturer & Exporter

A hex cap nut is a nut with a closed end. It hides the cut end of the bolt, keeps dirt and water out of the exposed thread, and leaves a smooth, safe finish where people or cables could touch it.

Exotic Alloy manufactures and exports hex cap nuts from Mumbai, India, for furniture and fit-out makers, railings and architectural metalwork, machinery and food equipment builders, and fastener distributors. We supply across India and export to Jordan, the Middle East, Africa and South-East Asia.

Two German standards

DIN 1587 is the high, domed cap nut, often called an acorn nut; DIN 917 is the low cap nut with a shallow crown, for tight spaces and larger sizes. Inch acorn nuts are on our acorn nuts page; for open nuts see hex nuts.

DIN 1587 DIN 917 A2 / A4 Coarse & fine thread Polished
Hex cap nuts at a glance
High, domed
DIN 1587:2021, M4–M24, grades A and B
Low, crowned
DIN 917:2021, M4–M64 here, grade A
Spanner
As ISO 4032 (16 mm at M10)
Height
1.7–2.0 d (1587); 1.13–1.5 d (917)
Longest bolt
Clamp + washer + t min
Materials
A2, A4, steel, brass
Related
Acorn nuts, hex nuts, washers
DIN 1587 domed cap nut M10 in section, to scale: hexagon 16 mm across flats and 8 mm high, dome 15 mm across with a 7.5 mm spherical radius, overall height 18 mm, thread 12.65 to 13.35 mm deep and at least 2 mm of wall at the crown; the bolt end must stay below the bottom of the thread bolt (dashed) bearing face h 18 m 8 t 12.65–13.35 crown wall w ≥ 2 dome SR 7.5 (dk 15) s 16 (spanner) DIN 1587 domed cap nut M10, section to scale The bolt must stop short of the thread end: protrusion beyond the bearing face < t min. EXOTIC ALLOY
A DIN 1587 M10 cap nut in section, to scale. The hexagon is as high as a DIN 934 nut; above it a short collar and a hemispherical dome close the end.
Specification

Hex Cap Nut Specification

The range we manufacture and export.

StandardsDIN 1587 (high, domed), DIN 917 (low)
SizesDIN 1587 M4–M24; DIN 917 M4–M64; M72 fine on request
ThreadMetric coarse; fine pitch on request
Product gradeDIN 1587 A and B; DIN 917 A
StainlessA2 (304), A4 (316)
Other materialsCarbon steel, brass, duplex on request
FinishPolished or plain stainless; zinc plated steel; nickel plated brass
Spanner sizesISO widths; old DIN widths (17, 19, 22, 32) on request
CertificationEN 10204 3.1; 3.2 on request
SupplyBoxed by size, or with bolts and washers
DIN 1587

DIN 1587 Domed Cap Nut Dimensions

High type, coarse thread, mm.

SizePitch PSpanner sHeight hHexagon m
max / min		Dome ⌀ dk / SRThread depth t
min / max		Crown wall w minh / d
M40.7783.2 / 2.96.5 / 3.255.26 / 5.7422.00
M50.88104 / 3.77.5 / 3.757.21 / 7.7922.00
M6110125 / 4.79.5 / 4.757.71 / 8.2922.00
M81.2513156.5 / 6.1412.5 / 6.2510.65 / 11.3521.88
M101.516188 / 7.6415 / 7.512.65 / 13.3521.80
M121.75182210 / 9.6417 / 8.515.65 / 16.3531.83
M142212511 / 10.320 / 1017.65 / 18.3541.79
M162242813 / 12.323 / 11.520.58 / 21.4241.75
M182.5273215 / 14.326 / 1324.58 / 25.4251.78
M202.5303416 / 14.928 / 1425.58 / 26.4251.70
M222.5343918 / 16.933 / 16.528.58 / 29.4251.77
M243364219 / 17.734 / 1730.5 / 31.561.75

DIN 1587:2021 (same values as 2014). s across flats, h overall height, m hexagon height (equal to the DIN 934 nut height), dk dome diameter, SR dome radius (half of dk: a hemisphere), t thread depth from the bearing face, w wall thickness at the crown. The 1987 edition used 17, 19, 22 and 32 mm spanners at M10, M12, M14 and M22.

DIN 917

DIN 917 Low Cap Nut Dimensions

SizePitch PSpanner sHeight h
max / min		Crown radius SRThread depth t
min / max		Crown wall w minh / d
M40.775.5 / 5.284.16 / 4.6411.38
M50.887 / 6.64104.96 / 5.4411.40
M61109 / 8.64126.71 / 7.291.51.50
M81.251312 / 11.57159.21 / 9.7921.50
M101.51614 / 13.572010.65 / 11.3521.40
M121.751816 / 15.572513.15 / 13.8521.33
M1422118 / 17.572814.65 / 15.3521.29
M1622420 / 19.483016.65 / 17.3521.25
M182.52722 / 21.483218.58 / 19.4221.22
M202.53025 / 24.483520.58 / 21.422.51.25
M222.53428 / 27.483521.58 / 22.4231.27
M2433630 / 29.484023.58 / 24.4231.25
M2734132 / 31.385025.58 / 26.4231.19
M303.54634 / 33.386027.58 / 28.4231.13
M3645544 / 43.387035.5 / 36.541.22
M424.56552 / 51.268041.5 / 42.541.24
M4857558 / 57.269047.5 / 48.541.21
M565.58568 / 67.2611055.4 / 56.651.21
M6469575 / 74.2613061.4 / 62.651.17

DIN 917:2021 (same values as 2015 and 2000), coarse thread, mm. SR is the radius of the shallow crown. The standard also lists M72; its 2015 and 2021 editions give different pitches, so we confirm M72 on order.

M12 nuts side by side to scale: a DIN 1587 domed cap nut 22 mm high with a 17 mm dome, a DIN 917 low cap nut 16 mm high with a shallow crown, and an ISO 4032 regular nut 10.8 mm high; all take an 18 mm spanner M12, side views to scale: high cap nut, low cap nut, regular nut h 22 DIN 1587 (high) domed, h ≈ 1.8 d h 16 DIN 917 (low) crown SR 25, h ≈ 1.3 d m 10.8 ISO 4032 (open) for comparison All three take an 18 mm spanner. DIN 917 crown drawn from its SR over the hexagon width (schematic). EXOTIC ALLOY
Same thread, same spanner, three heights. The domed nut stands 6 mm taller than the low cap nut at M12.
High vs low

DIN 1587 or DIN 917: Which Cap Nut

Overall height divided by thread diameter: DIN 1587 domed cap nuts lie between 1.70 d (M20) and 2.0 d (M4 to M6); DIN 917 low cap nuts between 1.13 d (M30) and 1.5 d (M6 and M8) Overall height h as a multiple of the thread diameter d 1.00 d 1.25 d 1.50 d 1.75 d 2.00 d DIN 1587 high M4: h 8 mm = 2.00 d DIN 1587 high M5: h 10 mm = 2.00 d DIN 1587 high M6: h 12 mm = 2.00 d DIN 1587 high M8: h 15 mm = 1.88 d DIN 1587 high M10: h 18 mm = 1.80 d DIN 1587 high M12: h 22 mm = 1.83 d DIN 1587 high M14: h 25 mm = 1.79 d DIN 1587 high M16: h 28 mm = 1.75 d DIN 1587 high M18: h 32 mm = 1.78 d DIN 1587 high M20: h 34 mm = 1.70 d DIN 1587 high M22: h 39 mm = 1.77 d DIN 1587 high M24: h 42 mm = 1.75 d DIN 1587 high DIN 917 low M4: h 5.5 mm = 1.38 d DIN 917 low M5: h 7 mm = 1.40 d DIN 917 low M6: h 9 mm = 1.50 d DIN 917 low M8: h 12 mm = 1.50 d DIN 917 low M10: h 14 mm = 1.40 d DIN 917 low M12: h 16 mm = 1.33 d DIN 917 low M14: h 18 mm = 1.29 d DIN 917 low M16: h 20 mm = 1.25 d DIN 917 low M18: h 22 mm = 1.22 d DIN 917 low M20: h 25 mm = 1.25 d DIN 917 low M22: h 28 mm = 1.27 d DIN 917 low M24: h 30 mm = 1.25 d DIN 917 low M27: h 32 mm = 1.19 d DIN 917 low M30: h 34 mm = 1.13 d DIN 917 low M36: h 44 mm = 1.22 d DIN 917 low M42: h 52 mm = 1.24 d DIN 917 low M48: h 58 mm = 1.21 d DIN 917 low M56: h 68 mm = 1.21 d DIN 917 low M64: h 75 mm = 1.17 d DIN 917 low M4 M8 M12 M16 M20 M24 M30 M36 M42 M48 M56 M64 DIN 1587 covers M4 to M24; DIN 917 M4 to M64 here (M72 fine thread on request). EXOTIC ALLOY
The domed nut is 1.7 to 2.0 d high, the low nut 1.13 to 1.5 d. Hover a dot for the value.

DIN 1587, high and domed

  • Round dome, the classic acorn look.
  • Deeper thread: more room for bolt length tolerance.
  • M4 to M24.

DIN 917, low and crowned

  • Shallow crown, low profile where space is short.
  • Less thread depth: the bolt length must be closer.
  • M4 to M64 here, so also for heavy machinery.
Bolt length

Choosing the Bolt Length for a Cap Nut

Choosing the bolt length under a DIN 1587 M10 cap nut: with a 20 mm clamped part the bolt end may stand at most 12.65 mm beyond it (t min), so a 30 mm bolt fits and leaves 10 mm in the thread, while a 35 mm bolt would hit the bottom of the thread before the nut is tight Bolt length under a cap nut, M10 DIN 1587 on a 20 mm part t min 12.65 Bolt 30 mm: end 10 mm above the part, fits t min 12.65 Bolt 35 mm: end 15 mm above the part, hits the thread end Rule: bolt length under the head ≤ clamped thickness (+ washers) + t min of the cap nut. EXOTIC ALLOY
A closed nut cannot run past the bolt end. Too long a bolt bottoms in the thread and the nut never clamps the joint.
  • Longest bolt: clamped thickness + washers + t min of the cap nut.
  • Shortest bolt: enough to engage at least 0.8 d of thread, the minimum height of a regular ISO 4032 nut.
  • Allow for the bolt length tolerance and any washer under the nut.
  • The finder below gives the range for your joint.
Finder

Cap Nut Finder: Dimensions & Bolt Length

Pick the nut and enter the joint; get the bolt length range and the order line.

Nut & joint

Dimensions from the tables on this page. Longest bolt = clamped part + washers + t min. Shortest bolt = clamped part + washers + 0.8 d, the thread length of a regular ISO 4032 nut at its minimum height. Bolt lengths are under the head.

Result
32.6
mm longest bolt (end at t min)
28
mm shortest bolt (0.8 d engaged)
Spanner / height:16 / 18 mm (hexagon 8)
Thread depth t:12.65 to 13.35 mm
Top:dome ⌀ 15, SR 7.5
Crown wall w min:2 mm
Designation:1000 pcs hexagon domed cap nut DIN 1587 – M10, stainless A2

Materials

Cap Nut Materials & Finishes

MaterialFinishWhere
Stainless A2 (304)Polished or plainIndoor fittings, furniture, railings, food equipment
Stainless A4 (316)Polished or plainOutdoor, coastal, marine and chemical areas
Carbon steelZinc platedMachinery guards and covers, indoor
BrassPlain or nickel platedDecorative and electrical fittings

Match the nut to the bolt: stainless on stainless, so no galvanic pair forms where water collects.

Stainless
A2 · A4

As in the photo.

304316
Carbon steel
Zinc plated

For indoor machinery.

10101035
Brass
Plain · nickel plated

Decorative and electrical.

Brass
Manufacturing

How Our Hex Cap Nuts Are Made

1

Wire / bar

Stainless, steel or brass, certified by heat.

2

Form

Hexagon and closed dome cold formed, or machined from bar.

3

Tap

Blind tapped to depth t, the crown left solid.

4

Polish

Dome and flats polished or tumbled.

5

Finish

Passivated, zinc or nickel plated.

6

Inspect

Thread and thread depth gauged.

Applications

Where Our Hex Cap Nuts Are Used

Furniture & fit-out

Exposed fixings on frames and fittings.

Railings & balustrades

Stainless glass clamps and posts.

Food equipment

Smooth ends that are easy to clean.

Machinery

Guards, covers and exposed studs.

Vehicles

Trim, bumpers and trailer fittings.

Playgrounds

Covered bolt ends on play equipment.

Quality & testing

Hex Cap Nut Inspection & Certification

CheckMethodApplied to
ThreadGO / NOT GO plug gaugesEvery lot
Thread depth tDepth gaugeEvery lot
s, h, domeCalipers, radius gaugeEvery lot
SurfaceVisual, polish standardEvery lot
MaterialHeat certificate, PMI on requestEvery heat
CoatingThickness gaugePlated lots

Every shipment includes

  • EN 10204 3.1 certificate
  • Lot number on every box
  • Packing list by size

On request

  • EN 10204 3.2 with third-party inspection
  • Salt spray tests on plated nuts
  • Sets with bolts and washers
FAQ

Hex Cap Nut Questions, Answered

A hexagon nut with a closed end that covers the end of the bolt, for a neat finish and to protect the thread and people from the cut end. DIN 1587 cap nuts are high with a round dome; DIN 917 cap nuts are low with a shallow crown.

Height and shape. At M12 a DIN 1587 nut is 22 mm high with a hemispherical dome 17 mm across, and a DIN 917 nut is 16 mm high with a shallow crown of 25 mm radius. DIN 1587 covers M4 to M24, DIN 917 runs much larger.

The same as an ISO 4032 nut: 16 mm at M10, 18 mm at M12, 21 mm at M14, 34 mm at M22, in the current editions of DIN 1587 and DIN 917. The 1987 edition of DIN 1587 used the older DIN widths 17, 19, 22 and 32 mm.

The bolt end must stop short of the bottom of the thread, so its length under the head should not exceed the clamped thickness plus washers plus the minimum thread depth t. A DIN 1587 M10 nut has t min 12.65 mm: on a 20 mm part a 30 mm bolt fits, a 35 mm bolt does not.

DIN 1587 M10: 12.65 to 13.35 mm; DIN 917 M10: 10.65 to 11.35 mm. Both are deeper than an ISO 4032 M10 nut is high (8.4 mm), so a correctly sized bolt engages at least as much thread.

Acorn nut is the everyday name for a domed cap nut such as DIN 1587. Inch acorn nuts are on our acorn nuts page.

Mostly stainless steel A2 (304) and A4 (316), as in the photo, for a clean finish that does not rust; also carbon steel, zinc plated, and brass, nickel plated or plain.
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