# T-bolts / hammer-head bolts: DIN 186 (square neck, M6–M48), DIN 787 (T-slot, M5–M48) and profile-slot hammer bolts: head length, width, height + DIN 186 envelopes

> What are the head length, width and height of a DIN 186 T-bolt (hammer-head bolt) for an M8 or M10, and what are the DIN 787 T-slot bolt dimensions?

- Category: Hardware › Fasteners
- Kind: Standard part
- Basis: fasten.it's DIN 186 and DIN 787 tables; McMaster-Carr's DIN 186 and DIN 787 listings (labelled head length, width, height) as the cross-check; one maker's hammer-head bolt for profile slot 8 (Fath); six DIN 186 envelope models as files
- Page: https://xemstudio.com/objects/t-bolts-din-186-din-787-hammer-head/ · JSON: https://xemstudio.com/api/geometry?object=t-bolts-din-186-din-787-hammer-head · Plain text: https://xemstudio.com/objects/t-bolts-din-186-din-787-hammer-head/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files CC BY 4.0 or their publisher's license
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

## Overall (mm)

| length | width | height |
|---|---|---|
| 36.0 | 20.0 | 73.0 |

**Exact dimensions.** Every file is drawn at true size with no tolerance added. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your process's clearance before making the part.

## Notes

- Millimetres. DIN 186 covers T-head (hammer-head) bolts with square neck, M6 to M48, forms A and B not given on the page; DIN 787 covers T-head bolts for the T-slots of DIN 650 machine-tool tables, M5 to M48 (02/2005). fasten.it does not define its column letters. The page prints the limit deviations of a (as '-0.3 / -0.5', '-0.3 / -0.6', '-0.4 / -0.7', '-0.4 / -0.8') once per merged group of rows starting at M5, M12, M30 and M48; the group extents are not clear in the text read, so they are not assigned to rows. McMaster-Carr prints head length, head width, head height and thread length for DIN 186 bolts by slot width, and for M6, M8, M10, M12, M16 and M20 they equal fasten.it's m, n, k and b: 16 × 6 × 4.5 with slot 6, 18 × 8 × 5.5, 21 × 10 × 7, 26 × 12 × 8, 30 × 16 × 10.5, 36 × 20 × 13. So for DIN 186 the page reads m as head length, n as head width, k as head height and b (l ≤ 125, ≤ 200, > 200) as thread length; M24 to M48 rows are fasten.it only.
- DIN 787 rows are fasten.it's a (slot width, with limit deviations), d2, e1, f, h1, h2 and k; the page does not define them and h2 is blank above M12. McMaster's DIN 787 listings (black oxide, for slot widths 6, 8, 10, 12, 14, 18 mm) print head length = head width and head height: 10 × 10 × 4, 13 × 13 × 6, 15 × 15 × 6, 18 × 18 × 7, 22 × 22 × 8, 28 × 28 × 10. e1 and k of fasten.it equal those head numbers for the 6, 8, 10, 12 and 14 mm slots; for the 18 mm slot fasten.it prints e1 25 and k 9 against McMaster's 28 and 10, so both are shown. McMaster lists no neck dimension and d2 is not interpreted here.
- Nominal lengths for DIN 787 on fasten.it: 25, 32, 40, 50, 63, 80, 100, 125, 160, 200, 250, 315, 400, 500 mm. McMaster's DIN 186 steel class 8.8 lengths run 25 to 200 mm.
- Hammer-head bolt for aluminium profile: Fath's slot 8 bolt is M6 (16–60 mm) or M8 (20–40 mm), profile type B with H 1.5 mm or type I with H 3.0 mm, and h 4.7 mm; the page does not define H and h and prints no head length or width. item's Hammerhead Nut 8 M6 (profile line 8; torque 6 Nm, permissible load 1,000 N) does not print the head size either (CAD and data sheet need a login). The slot geometry itself is on the extrusion pages (2020-t-slot-extrusion-inch and the T-nut pages).
- Files are Xem-drawn envelopes of DIN 186, not the real bolt: a rectangular head m × n × k on a plain cylinder at the nominal diameter, 60 mm under the head for M6, M8, M10, M12, M16 and M20 (the length is an example chosen by Xem; it is longer than the thread length b in every case). The square neck under the head and the rounded head ends are not published as numbers in the sources read, and the thread is a plain cylinder. DIN 787 is numbers only: its head shape is not defined by the letters read.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| head width n | 6, 8, 10, 12, 16, 20 mm for M6, M8, M10, M12, M16, M20 | T-slot opening of the same width (McMaster lists DIN 186 bolts by 'for slot width'; the slot's cavity is not on this page) | slide | all |

## Sizes

| standard / maker | thread | pitch | thread length b | head length | head width | head height | other numbers as printed |
|---|---|---|---|---|---|---|---|
| DIN 186 T-head bolt, square neck | M6 | 1 | b 18 / — / — (l ≤ 125 / ≤ 200 / > 200) | 16 | 6 | 4.5 | head m × n × k = length × width × height (matches McMaster for M6–M20) |
| DIN 186 T-head bolt, square neck | M8 | 1.25 | b 22 / — / — (l ≤ 125 / ≤ 200 / > 200) | 18 | 8 | 5.5 | head m × n × k = length × width × height (matches McMaster for M6–M20) |
| DIN 186 T-head bolt, square neck | M10 | 1.5 | b 26 / — / — (l ≤ 125 / ≤ 200 / > 200) | 21 | 10 | 7 | head m × n × k = length × width × height (matches McMaster for M6–M20) |
| DIN 186 T-head bolt, square neck | M12 | 1.75 | b 30 / — / — (l ≤ 125 / ≤ 200 / > 200) | 26 | 12 | 8 | head m × n × k = length × width × height (matches McMaster for M6–M20) |
| DIN 186 T-head bolt, square neck | M16 | 2 | b 38 / 44 / — (l ≤ 125 / ≤ 200 / > 200) | 30 | 16 | 10.5 | head m × n × k = length × width × height (matches McMaster for M6–M20) |
| DIN 186 T-head bolt, square neck | M20 | 2.5 | b 46 / 52 / 65 (l ≤ 125 / ≤ 200 / > 200) | 36 | 20 | 13 | head m × n × k = length × width × height (matches McMaster for M6–M20) |
| DIN 186 T-head bolt, square neck | M24 | 3 | b 54 / 60 / 73 (l ≤ 125 / ≤ 200 / > 200) | 43 | 24 | 15 | page's letters m, n, k |
| DIN 186 T-head bolt, square neck | M30 | 3.5 | b 66 / 72 / 85 (l ≤ 125 / ≤ 200 / > 200) | 54 | 30 | 19 | page's letters m, n, k |
| DIN 186 T-head bolt, square neck | M36 | 4 | b 78 / 84 / 97 (l ≤ 125 / ≤ 200 / > 200) | 66 | 36 | 23 | page's letters m, n, k |
| DIN 186 T-head bolt, square neck | M42 | 4.5 | b — / 96 / 109 (l ≤ 125 / ≤ 200 / > 200) | 80 | 42 | 26 | page's letters m, n, k |
| DIN 186 T-head bolt, square neck | M48 | 5 | b — / 108 / 121 (l ≤ 125 / ≤ 200 / > 200) | 88 | 48 | 30 | page's letters m, n, k |
| DIN 787 T-slot bolt (DIN 650 slots) | M5 | — | — | — | — | — | a 5; d2 10; e1 9; f 1; h1 6.5; h2 10; k 3 |
| DIN 787 T-slot bolt (DIN 650 slots) | M6 | — | — | 10 | 10 | 4 | a 6; d2 12; e1 10; f 1.6; h1 8; h2 13; k 4; McMaster: 10 × 10 × 4 |
| DIN 787 T-slot bolt (DIN 650 slots) | M8 | — | — | 13 | 13 | 6 | a 8; d2 16; e1 13; f 1.6; h1 12; h2 18; k 6; McMaster: 13 × 13 × 6 |
| DIN 787 T-slot bolt (DIN 650 slots) | M10 | — | — | 15 | 15 | 6 | a 10; d2 20; e1 15; f 1.6; h1 14; h2 21; k 6; McMaster: 15 × 15 × 6 |
| DIN 787 T-slot bolt (DIN 650 slots) | M12 | — | — | 18 | 18 | 7 | a 12; d2 25; e1 18; f 2.5; h1 16; h2 25; k 7; McMaster: 18 × 18 × 7 |
| DIN 787 T-slot bolt (DIN 650 slots) | M12 | — | — | 22 | 22 | 8 | a 14; d2 28; e1 22; f 2.5; h1 20; h2 —; k 8; McMaster: 22 × 22 × 8 |
| DIN 787 T-slot bolt (DIN 650 slots) | M16 | — | — | 28 | 28 | 10 | a 18; d2 36; e1 25; f 2.5; h1 24; h2 —; k 9; McMaster head 28 × 28 × 10 differs from e1 25 and k 9; McMaster: 28 × 28 × 10 |
| DIN 787 T-slot bolt (DIN 650 slots) | M20 | — | — | — | — | — | a 22; d2 45; e1 35; f 2.5; h1 32; h2 —; k 14 |
| DIN 787 T-slot bolt (DIN 650 slots) | M24 | — | — | — | — | — | a 28; d2 56; e1 40; f 4; h1 41; h2 —; k 16 |
| DIN 787 T-slot bolt (DIN 650 slots) | M30 | — | — | — | — | — | a 36; d2 70; e1 54; f 6; h1 50; h2 —; k 22 |
| DIN 787 T-slot bolt (DIN 650 slots) | M36 | — | — | — | — | — | a 42; d2 82; e1 65; f 6; h1 60; h2 —; k 26 |
| DIN 787 T-slot bolt (DIN 650 slots) | M42 | — | — | — | — | — | a 48; d2 95; e1 75; f 6; h1 70; h2 —; k 30 |
| DIN 787 T-slot bolt (DIN 650 slots) | M48 | — | — | — | — | — | a 54; d2 110; e1 85; f 6; h1 80; h2 —; k 34 |
| Hammer-head bolt, profile slot 8 (Fath) | M6 × 16, 20, 25, 30, 40, 60; M8 × 20, 25, 30, 40 | — | — | — | — | — | H 1.5 (type B) or 3.0 (type I) mm; h 4.7 mm; steel or stainless 1.4301; letters not defined on the page |

## Where the files are

- fasten.it: [DIN 186 T-head bolts with square neck, M6 to M48 (09/2010): P, b by length, k, n, m. The page does not define the letters; head k, n, m match the head height, width and length McMaster prints for the same sizes](https://fasten.it/en/norms/norm/din_186) — web — Reference page; numbers only
- fasten.it: [DIN 787 T-head bolts for T-slots (DIN 650), M5 to M48 (02/2005): a, limit deviations, d2, e1, f, h1, h2, k; nominal lengths 25 to 500 mm. The page does not define the letters](https://fasten.it/en/norms/norm/din_787) — web — Reference page; numbers only
- McMaster-Carr: [Metric T-slot bolts (DIN 186 and DIN 787 listings with head length, width, height) (free STEP/IGES per part, for your own design use; no redistribution)](https://www.mcmaster.com/metric-t-slot-bolts) — STEP, IGES, PDF — McMaster-Carr site terms: personal design use, no redistribution (verify at link)
- Fath (via fath24): [Hammer head bolt for aluminium profile slot 8: M6 x 16 to 60 and M8 x 20 to 40, H 1.5 / 3.0 mm, h 4.7 mm, profile type B / I, steel or A2 stainless](https://www.fath24.com/de/Hammerschraube-Nut-8/096HK0815M0630) — web — Maker shop page; numbers only. H and h are not defined on the page
- item Industrietechnik: [Hammerhead Nut 8 M6 (profile line 8): self-locking, torque 6 Nm, permissible load 1,000 N; slot width and hammer head size are not on the page (CAD / data sheet need login)](https://www.item24.com/en-be/hammerhead-nut-8-m6-bright-zinc-plated-62606) — web — Maker product page; maker CAD is available after login

## Free STEP/STL (6 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/t-bolts-din-186-din-787-hammer-head/index.json

- t-bolt-din-186-m6x60-envelope: [STEP](https://xemstudio.com/files/hardware/t-bolts-din-186-din-787-hammer-head/t-bolt-din-186-m6x60-envelope.step) · [STL](https://xemstudio.com/files/hardware/t-bolts-din-186-din-787-hammer-head/t-bolt-din-186-m6x60-envelope.stl) — DIN 186 M6 T-head bolt envelope: rectangular head 16 long × 6 wide × 4.5 high (m × n × k) on a plain Ø6 shank, example length 60 mm under the head (Xem's choice); no square neck, rounded head ends or thread
- t-bolt-din-186-m8x60-envelope: [STEP](https://xemstudio.com/files/hardware/t-bolts-din-186-din-787-hammer-head/t-bolt-din-186-m8x60-envelope.step) · [STL](https://xemstudio.com/files/hardware/t-bolts-din-186-din-787-hammer-head/t-bolt-din-186-m8x60-envelope.stl) — DIN 186 M8 T-head bolt envelope: rectangular head 18 long × 8 wide × 5.5 high (m × n × k) on a plain Ø8 shank, example length 60 mm under the head (Xem's choice); no square neck, rounded head ends or thread
- t-bolt-din-186-m10x60-envelope: [STEP](https://xemstudio.com/files/hardware/t-bolts-din-186-din-787-hammer-head/t-bolt-din-186-m10x60-envelope.step) · [STL](https://xemstudio.com/files/hardware/t-bolts-din-186-din-787-hammer-head/t-bolt-din-186-m10x60-envelope.stl) — DIN 186 M10 T-head bolt envelope: rectangular head 21 long × 10 wide × 7 high (m × n × k) on a plain Ø10 shank, example length 60 mm under the head (Xem's choice); no square neck, rounded head ends or thread
- t-bolt-din-186-m12x60-envelope: [STEP](https://xemstudio.com/files/hardware/t-bolts-din-186-din-787-hammer-head/t-bolt-din-186-m12x60-envelope.step) · [STL](https://xemstudio.com/files/hardware/t-bolts-din-186-din-787-hammer-head/t-bolt-din-186-m12x60-envelope.stl) — DIN 186 M12 T-head bolt envelope: rectangular head 26 long × 12 wide × 8 high (m × n × k) on a plain Ø12 shank, example length 60 mm under the head (Xem's choice); no square neck, rounded head ends or thread
- t-bolt-din-186-m16x60-envelope: [STEP](https://xemstudio.com/files/hardware/t-bolts-din-186-din-787-hammer-head/t-bolt-din-186-m16x60-envelope.step) · [STL](https://xemstudio.com/files/hardware/t-bolts-din-186-din-787-hammer-head/t-bolt-din-186-m16x60-envelope.stl) — DIN 186 M16 T-head bolt envelope: rectangular head 30 long × 16 wide × 10.5 high (m × n × k) on a plain Ø16 shank, example length 60 mm under the head (Xem's choice); no square neck, rounded head ends or thread
- t-bolt-din-186-m20x60-envelope: [STEP](https://xemstudio.com/files/hardware/t-bolts-din-186-din-787-hammer-head/t-bolt-din-186-m20x60-envelope.step) · [STL](https://xemstudio.com/files/hardware/t-bolts-din-186-din-787-hammer-head/t-bolt-din-186-m20x60-envelope.stl) — DIN 186 M20 T-head bolt envelope: rectangular head 36 long × 20 wide × 13 high (m × n × k) on a plain Ø20 shank, example length 60 mm under the head (Xem's choice); no square neck, rounded head ends or thread

## Questions

**What are the head dimensions of a DIN 186 M10 T-bolt?**

21 mm long, 10 mm wide and 7 mm high; thread length 26 mm for lengths up to 125 mm (fasten.it; McMaster prints the same head for a 10 mm slot).

**What is the head of a DIN 787 T-slot bolt for a 12 mm slot?**

fasten.it's e1 is 18 mm and k 7 mm; McMaster prints a head 18 × 18 × 7 mm.

**What is the thread length of a DIN 186 M12?**

30 mm for lengths up to 125 mm (fasten.it; McMaster prints 30 mm for 12 mm slot bolts of 40 to 100 mm and 36 mm for 120 mm).

## Fits with

- [Slide-in T-nuts for 20, 30, 40, 45 mm and 1 in, 1.5 in T-slot extrusion](https://xemstudio.com/objects/slide-in-t-nuts/)
- [Drop-in T-nuts for 20, 30, 40, 45 mm and 1 in, 1.5 in T-slot extrusion](https://xemstudio.com/objects/drop-in-t-nuts/)
- [L corner brackets for 20, 30, 40, 45 mm and 1 in, 1.5 in T-slot extrusion](https://xemstudio.com/objects/t-slot-corner-brackets/)
- [Carriage bolts, ASME B18.5 round head square neck, #10 to 1 in: head, square neck, body diameter + envelope models](https://xemstudio.com/objects/carriage-bolts-asme-b18-5/)
- [Hex head screws, M3–M8 (ISO 4017)](https://xemstudio.com/objects/hex-head-screws-metric/)
- [2020 T-slot extrusion, 2 × 2 in (10-series inch)](https://xemstudio.com/objects/2020-t-slot-extrusion-inch/)