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DIN 508 · DIN 650 / ISO 299 slots · Class 10

T-Slot Nuts Manufacturer in India

The anchor under every clamp on a machine table. We make T-slot nuts to DIN 508, M4 to M48 for T-slots 5 to 54 mm wide, in quenched and tempered class 10 steel. Below: the nut to scale, the full dimension table, how it clamps in the slot, the tongue fit and a slot finder.

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  • ISO 9001:2015 certified manufacturer
  • Property class 10
  • Slots 5 to 54 mm
  • EN 10204 3.1 / 3.2
Zinc plated DIN 508 T-slot nuts with a raised tongue on a square base
DIN 508 M4 – M48 Slots 5 – 54 mm Class 10 steel
Overview

DIN 508 T-Slot Nuts: Manufacturer & Exporter

A T-slot nut turns the slots of a machine table into anchor points. Slid in from the end of the slot, it can be placed anywhere along it, and a stud screwed into it holds a clamp, a vice or a fixture down on the table.

Exotic Alloy manufactures and exports T-slot nuts from Mumbai, India, for machine tool builders, tool rooms, fixture makers, press shops and fastener distributors. We supply across India and export to Zambia, Southern and East Africa, the Middle East and South-East Asia.

One standard, sixteen slots

DIN 508 sizes the nut by the slot it fits: the tongue is the slot width less 0.3 to 0.5 mm, and each slot width has its own thread, from M4 in a 5 mm slot to M48 in a 54 mm slot. The nuts fit T-slots to DIN 650 and ISO 299. For the studs see full threaded studs; for the nut on top hex flange nuts; for bolts with a T-head T-head screws.

DIN 508 M4 – M48 Class 10 Black or zinc Stainless to order
T-slot nuts at a glance
Standard
DIN 508
Sizes
M4 x 5 to M48 x 54
T-slots
DIN 650, ISO 299
Tongue
Slot width −0.3 / −0.5 mm
Strength
Property class 10
Finish
Plain, black oxide, zinc
Related
Studs, flange nuts, washers
DIN 508 T-slot nut M12 for a 14 mm T-slot, to scale: tongue 13.5 to 13.7 mm wide and 8 mm high, base 22 mm square and 8 mm high, 16 mm overall DIN 508 T-slot nut M12 (for a 14 mm slot), to scale tongue a 13.5–13.7 base e 22 h 16 base k 8 Front view (across the slot) Top view: base 22 × 22, tongue along the slot Top view Base-edge chamfers drawn schematically; widths and heights to scale. Thread runs through (dashed). EXOTIC ALLOY
A DIN 508 M12 nut to scale. The tongue rides in the slot neck, the square base bears on the slot shoulders.
Specification

T-Slot Nut Specification

The range we manufacture and export.

StandardDIN 508
SizesM4 x 5 to M48 x 54
T-slotsDIN 650, ISO 299
ThreadMetric coarse, right hand, through
Property class10; 8 on request
MaterialQuenched and tempered steel
FinishPlain, black oxide, zinc plated
StainlessA2 (304) to order
CertificationEN 10204 3.1; 3.2 on request
SupplyBoxed by size, or in sets with studs
DIN 508

DIN 508 T-Slot Nut Dimensions

Metric coarse thread, mm.

ThreadT-slot widthTongue a
slot −0.3 / −0.5		Base e
−0.5		Base height kOverall height hTongue height h − k
M454.5 – 4.7936.53.5
M565.5 – 5.710484
M687.5 – 7.7136104
M8109.5 – 9.7156126
M101211.5 – 11.7187147
M121413.5 – 13.7228168
M141615.5 – 15.7259189
M161817.5 – 17.728102010
M182019.5 – 19.732122412
M202221.5 – 21.735142814
M222423.5 – 23.740163216
M242827.5 – 27.744183618
M303635.5 – 35.754224422
M364241.5 – 41.765265226
M424847.5 – 47.775306030
M485453.5 – 53.785347036

DIN 508:2002 from fasten.it (M5 to M30, with the tolerances), checked against OPAC's DIN 508 catalogue (M4 to M48) and McMaster-Carr's DIN 508 range (M4 to M48): every slot width, base, base height and overall height agrees in at least two of the three, and in all three from M5 to M30. The base is square, e by e. OPAC gives its actual tongue width as the slot less 0.4 mm (less 0.5 mm at M30), inside the −0.3 / −0.5 mm tolerance. Status: DIN 508:2002-06 was withdrawn in January 2024 and a new draft, DIN 508:2026-08, has been out for comment; we will check these figures against the new edition when it is published. M27 x 32 is listed by OPAC only and is made to order.

In the slot

How a T-Slot Nut Clamps

Section through a 14 mm T-slot in a machine table: the DIN 508 M12 nut sits with its base in the wide part of the slot and its tongue in the neck; a stud and flange nut pull a strap clamp down on the work How it works: M12 nut in a 14 mm T-slot (slot outline schematic) flange nut strap clamp work heel block stud DIN 508 nut: base under the slot shoulders machine table stud end flush with base Tightening the flange nut pulls the T-slot nut up against the slot shoulders and clamps the work through the strap. EXOTIC ALLOY
Nut, stud, clamp. The nut is drawn to scale; the slot outline is schematic, because the DIN 650 / ISO 299 slot table is not freely published.
  • Base: wider than the slot, it hooks under the shoulders and takes the clamping load.
  • Tongue: a sliding fit in the slot neck, it stops the nut turning as the stud is screwed in.
  • Stud: screwed through the full height of the nut, end flush with the base.
  • Top: a strap clamp, washer and flange nut, or a vice or fixture bolted straight down.
Tongue fit

Tongue Width and Slot Clearance

Tongue fit in a 14 mm T-slot, widths enlarged 30 times: the tongue is 0.3 to 0.5 mm narrower than the slot, so the nut slides along the slot and stays square to it Tongue fit: 14 mm slot, tongue 13.5 to 13.7 mm (widths 30 times full size) slot 14 tongue 13.7 max (solid edge) 13.5 min (dashed amber) gap 0.15 to 0.25 mm each side, 0.3 to 0.5 mm in total Widths drawn 30 times full size, heights not to scale. Tongue tolerance −0.3 / −0.5 mm from DIN 508 (fasten.it). EXOTIC ALLOY
A sliding fit. Loose enough to slide, close enough to keep the nut square in the slot.

The tongue of every DIN 508 nut is made 0.3 to 0.5 mm under the nominal slot width, so a nut for a 14 mm slot has a 13.5 to 13.7 mm tongue. A nut one size down will drop into a bigger slot but rock and turn; one size up will not go in. Measure the slot at its top edge and choose the nut by that width, not by the thread: the thread follows from the slot.

Sizes & use

T-Slot Nut Sizes and Good Practice

DIN 508 nut sizes from M4 to M48: T-slot width 5 to 54 mm, base 9 to 85 mm and overall height 6.5 to 70 mm DIN 508 nut by size, mm: T-slot width, base e and overall height h T-slot width Base e Height h 0 15 30 45 60 75 90 M4 T-slot width: 5 mm M4 Base e: 9 mm M4 Height h: 6.5 mm M4 M5 T-slot width: 6 mm M5 Base e: 10 mm M5 Height h: 8 mm M5 M6 T-slot width: 8 mm M6 Base e: 13 mm M6 Height h: 10 mm M6 M8 T-slot width: 10 mm M8 Base e: 15 mm M8 Height h: 12 mm M8 M10 T-slot width: 12 mm M10 Base e: 18 mm M10 Height h: 14 mm M10 M12 T-slot width: 14 mm M12 Base e: 22 mm M12 Height h: 16 mm M12 M14 T-slot width: 16 mm M14 Base e: 25 mm M14 Height h: 18 mm M14 M16 T-slot width: 18 mm M16 Base e: 28 mm M16 Height h: 20 mm M16 M18 T-slot width: 20 mm M18 Base e: 32 mm M18 Height h: 24 mm M18 M20 T-slot width: 22 mm M20 Base e: 35 mm M20 Height h: 28 mm M20 M22 T-slot width: 24 mm M22 Base e: 40 mm M22 Height h: 32 mm M22 M24 T-slot width: 28 mm M24 Base e: 44 mm M24 Height h: 36 mm M24 M30 T-slot width: 36 mm M30 Base e: 54 mm M30 Height h: 44 mm M30 M36 T-slot width: 42 mm M36 Base e: 65 mm M36 Height h: 52 mm M36 M42 T-slot width: 48 mm M42 Base e: 75 mm M42 Height h: 60 mm M42 M48 T-slot width: 54 mm M48 Base e: 85 mm M48 Height h: 70 mm M48 fasten.it (DIN 508:2002), OPAC and McMaster-Carr agree on every value shown. Hover a bar for the value. EXOTIC ALLOY
Sixteen sizes from 5 to 54 mm slots. The base grows faster than the slot.
  • Thread fully: the nut carries its full load only with the stud engaged over its whole height.
  • Do not bottom: a stud that sticks out below the base presses on the slot floor and pushes the nut off the shoulders.
  • Match the class: class 10 nuts are made for studs and bolts up to property class 10.9.
  • Keep slots clean of chips so the base sits flat on both shoulders.
  • Place the nut directly under the clamp, not near an open end of the slot.
  • Replace nuts with stretched threads or a worn or spread base.
Finder

T-Slot Nut Finder: Slot Width to Nut

Enter the measured slot width, and the space under the shoulders if you know it; get the DIN 508 nut, the tongue clearance, a fit check and the order line.

Your T-slot

Dimensions from the DIN 508 table on this page. The finder takes the largest DIN 508 nut whose tongue (slot width −0.3 mm at most) goes into your measured slot. If you enter the space under the shoulders, it checks that the base e and base height k go in.

Result
M12
for a 14 mm slot
22
mm square base
Tongue:13.5–13.7 mm wide, 8 mm high
Clearance:0.3–0.5 mm
Heights:base 8, overall 16 mm
Thread:M12 x 1.75, through
Under shoulders:not entered
Designation:100 pcs T-slot nut DIN 508 – M12 x 14, steel class 10, black oxide

Materials

T-Slot Nut Materials & Finishes

MaterialStrengthFinishWhere
Quenched and tempered steelProperty class 10Plain or black oxideMachine tables, the standard choice
Quenched and tempered steelProperty class 10Zinc plated, as in the photoFixtures and jigs in damp shops
SteelProperty class 8Plain or zinc platedLight clamping, on request
Stainless A2 (304)Lower than class 10PlainWet, food and clean areas, to order

OPAC and Hoffmann list DIN 508 nuts in quenched and tempered steel of property class 10, and Aspen in class 10 steel for bolts and studs up to class 10.9. Class 8: some stockists sell class 8 nuts under DIN 508, so state the class on your order.

Medium carbon
Quenched & tempered

For class 10 nuts.

1045
Alloy steel
Large sizes

Through hardening in heavy sections.

4140
Stainless
A2

Wet and clean areas.

304
Manufacturing

How Our T-Slot Nuts Are Made

1

Material

Steel bar or flat with heat certificate.

2

Form

Profile milled or forged, cut to length.

3

Drill & tap

Thread tapped square to the base.

4

Harden

Quenched and tempered to class 10.

5

Finish

Black oxide or zinc plated.

6

Inspect

Thread, tongue and hardness checked.

Applications

Where Our T-Slot Nuts Are Used

Milling machines

Vices, clamps and work held on the table.

Machining centres

Fixtures and pallets bolted down.

Presses

Dies clamped to bolsters and rams.

Tool rooms

Clamping kits for setups.

Welding tables

Jigs held on slotted tables.

Inspection

Angle plates on surface tables.

Quality & testing

T-Slot Nut Inspection & Certification

CheckMethodApplied to
ThreadGO / NOT GO plug gaugesEvery lot
Tongue widthMicrometer, against the −0.3 / −0.5 mm limitsEvery lot
Base and heightsCalipersEvery lot
HardnessRockwell or VickersEvery heat-treatment batch
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
  • Hardness test report per lot
  • Sets with studs, washers and flange nuts
FAQ

T-Slot Nut Questions, Answered

A nut with a raised tongue on a wider square base. It slides into the T-slot of a machine table: the base sits under the slot shoulders, the tongue in the narrow neck keeps it from turning, and a stud screwed into it clamps work or fixtures to the table. The usual metric type is DIN 508, M4 to M48 for slots 5 to 54 mm wide.

DIN 508 M12 x 14. Its tongue is 13.5 to 13.7 mm wide, the base is 22 mm square and 8 mm high, and the nut is 16 mm high overall.

In DIN 508: 5 mm slot M4, 6 mm M5, 8 mm M6, 10 mm M8, 12 mm M10, 14 mm M12, 16 mm M14, 18 mm M16, 20 mm M18, 22 mm M20, 24 mm M22, 28 mm M24, 36 mm M30, 42 mm M36, 48 mm M42 and 54 mm M48.

By thread and slot width, for example T-slot nut DIN 508 M12 x 14, with the property class (normally 10), the finish and the quantity.

They are normally made of quenched and tempered steel in property class 10, for studs and bolts up to property class 10.9. Some stockists sell class 8 nuts under the same number, so state the class when you order.

Through the full height of the nut, with its end flush with the base. The nut only carries its full load when the whole thread is engaged, and a stud that sticks out below the base presses on the bottom of the slot and pushes the nut away from the shoulders.

DIN 508:2002-06 was withdrawn in January 2024 and a new draft, DIN 508:2026-08, has been out for public comment. T-slot nuts are still made and ordered to the DIN 508 dimensions, for T-slots to DIN 650 and ISO 299.

Quenched and tempered steel in property class 10, plain, black oxide or zinc plated like the nuts in the photo. Stainless steel nuts are made to order for wet and clean areas; they are not as strong as class 10 steel.
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