Set Screws Manufacturer in India | Socket Set Screws & Grub Screws

Overview

Socket Set Screws & Grub Screws (ISO 4026–4029, ASME B18.3): Manufacturer & Stockist

A set screw has no head: it disappears into its tapped hole and presses its point against a shaft or part to stop it moving.

Exotic Alloy manufactures set screws in Mumbai, India, for gear, pulley, coupling, collar, knob and instrument makers. We stock across India and supply Ghana, Africa, the Gulf, Asia and Europe. Socket set screws are cold formed and hardened; stainless set screws are made in A1, A2 and A4.

One drive, many points

All socket set screws are turned with a hex key (Allen key) from the socket end. What changes is the point: flat, cone, dog and cup in ISO, plus oval and half dog in inch. For the full Allen family see Allen bolts; for square head set screws see square head screws.

ISO 4026–4029 DIN 913–916 ASME B18.3 45H steel A2 / A4

Set screw at a glance

Head: None; threaded full length
Drive: Hex socket (slot on ISO 4766)
Points: Flat, cone, dog, cup, oval, half dog
Length: Overall
Strength: 45H; inch HRC 45–53
Related: Allen bolts, socket cap, square head

ISO 4029 M8 × 12 cup point socket set screw, drawn to scale. Thread, socket and cup shown schematically; socket end view.

Specification

Set Screw Specification

The range we manufacture and supply.

StandardsISO 4026 / 4027 / 4028 / 4029 (ex DIN 913 / 914 / 915 / 916); ISO 4766 (ex DIN 551); ASME B18.3

Size rangeM1.6–M24 socket; M1.2–M12 slotted; No. 0–1″ inch

ThreadMetric coarse (fine to order); UNC and UNF

LengthsOverall length, standard steps; specials to order

DriveHex socket 0.7–12 mm and 0.028–9/16″; slot

PointsFlat, cone, dog (short / long), cup; inch oval and half dog

MaterialsAlloy steel 45H (ISO 898-5); stainless A1 / A2 / A4 (ISO 3506-3); brass to order

FinishBlack oxide, zinc plated; stainless plain or passivated

CertificationMill certificate; EN 10204 3.1; hardness reports

PackingBoxes of 100 to 5,000; nylon patch to order

Point styles

Set Screw Points: Flat, Cone, Dog, Cup, Oval & Half Dog

The point decides how the screw holds and what it does to the shaft.

Six points at the same scale, four ISO (M8) and two inch only (5/16″, about the same size).

Point	Standard	Use	Shaft
Cup	ISO 4029 / DIN 916	The everyday choice; the cup edge bites in	Softer than the screw; marks it
Flat	ISO 4026 / DIN 913	Frequent resetting, least damage	Best against a ground flat
Cone	ISO 4027 / DIN 914	Permanent setting, deep seat; also a pivot	In a drilled spot
Dog	ISO 4028 / DIN 915	Positive location	In a drilled hole or slot
Oval	ASME B18.3	Frequent resetting, grooves, angled seats	Little deformation
Half dog	ASME B18.3	Permanent setting; often used instead of a dowel pin	Close fit in a hole or against a flat

Dimensions

Set Screw Dimensions & Key Sizes

ISO socket set screws from M1.6 to M24, socket end, at the same scale, with the hex key size.

Size	P	s key hex socket	e min	t socket depth min, by length	Flat / dog d_p 4026 / 4028, max	Cone d_t 4027, max	Cup d_z 4029, max	Dog z short / long, max	Tap drill d − P
M1.6	0.35	0.7	0.809	0.7–1.5	0.8	0.4	0.8	0.65 / 1.05	1.25
M2	0.4	0.9	1.011	0.8–1.7	1	0.5	1	0.75 / 1.25	1.6
M2.5	0.45	1.3	1.454	1.2–2	1.5	0.65	1.2	0.88 / 1.5	2.05
M3	0.5	1.5	1.733	1.2–2	2	0.75	1.4	1 / 1.75	2.5
M4	0.7	2	2.303	1.5–2.5	2.5	1	2	1.25 / 2.25	3.3
M5	0.8	2.5	2.873	2–3	3.5	1.25	2.5	1.5 / 2.75	4.2
M6	1	3	3.443	2–3.5	4	1.5	3	1.75 / 3.25	5
M8	1.25	4	4.583	3–5	5.5	2	5	2.25 / 4.3	6.75
M10	1.5	5	5.723	4–6	7	2.5	6	2.75 / 5.3	8.5
M12	1.75	6	6.863	4.8–8	8.5	3	8	3.25 / 6.3	10.25
M16	2	8	9.149	6.4–10	12	4	10	4.3 / 8.36	14
M20	2.5	10	11.429	8–12	15	5	14	5.3 / 10.36	17.5
M24	3	12	13.716	10–15	18	6	16	6.3 / 12.43	21

ISO 4026 / 4027 / 4028 / 4029 (2004), mm. Socket depth t depends on length: the lower value applies to the shortest screws. Dog length z: short / long dog point (ISO 4028).

Size	UNC	Key J	T key engagement min	C cup / flat max / min	R oval basic	Cone 90° from length Y	Half dog P max / min	Half dog Q max / min	Torque in-lb
No. 0	80	0.028	.050	.033 / .027	.045	.090″	.040 / .037	.017 / .013	0.86
No. 1	64	0.035	.060	.040 / .033	.055	.090″	.049 / .045	.021 / .017	1.8
No. 2	56	0.035	.060	.047 / .039	.064	.130″	.057 / .053	.024 / .020	1.8
No. 3	48	0.050	.070	.054 / .045	.074	.130″	.066 / .062	.027 / .023	5
No. 4	40	0.050	.070	.061 / .051	.084	.190″	.075 / .070	.030 / .026	5
No. 5	40	1/16″	.080	.067 / .057	.094	.190″	.083 / .078	.033 / .027	9.5
No. 6	32	1/16″	.080	.074 / .064	.104	.190″	.092 / .087	.038 / .032	9.5
No. 8	32	5/64″	.090	.087 / .076	.123	.250″	.109 / .103	.043 / .037	19.4
No. 10	24	3/32″	.100	.102 / .088	.142	.250″	.127 / .120	.049 / .041	33.5
1/4″	20	1/8″	.125	.132 / .118	.188	.310″	.156 / .149	.067 / .059	77.9
5/16″	18	5/32″	.156	.172 / .156	.234	.380″	.203 / .195	.082 / .074	156
3/8″	16	3/16″	.188	.212 / .194	.281	.440″	.250 / .241	.099 / .089	273
7/16″	14	7/32″	.219	.252 / .232	.328	.500″	.297 / .287	.114 / .104	428
1/2″	13	1/4″	.250	.291 / .270	.375	.570″	.344 / .334	.130 / .120	615
5/8″	11	5/16″	.312	.371 / .347	.469	.750″	.469 / .456	.164 / .148	1315
3/4″	10	3/8″	.375	.450 / .425	.562	.880″	.562 / .549	.196 / .180	2150
7/8″	9	1/2″	.500	.530 / .502	.656	1.000″	.656 / .642	.227 / .211	5130
1″	8	9/16″	.562	.609 / .579	.750	1.130″	.750 / .734	.260 / .240	7010

ASME B18.3-2003 alloy steel socket set screws, inch. Cone point 90° for lengths from Y up, 118° for shorter screws. Torque = tightening (test) torque the socket must take without reaming.

Size	P	n slot nom	t slot depth min / max	d_p flat point max
M1.2	0.25	0.2	0.4 / 0.52	0.6
M1.6	0.35	0.25	0.56 / 0.74	0.8
M2	0.4	0.25	0.64 / 0.84	1
M2.5	0.45	0.4	0.72 / 0.95	1.5
M3	0.5	0.4	0.8 / 1.05	2
M3.5	0.6	0.5	0.96 / 1.21	2.2
M4	0.7	0.6	1.12 / 1.42	2.5
M5	0.8	0.8	1.28 / 1.63	3.5
M6	1	1	1.6 / 2	4
M8	1.25	1.2	2 / 2.5	5.5
M10	1.5	1.6	2.4 / 3	7
M12	1.75	2	2.8 / 3.6	8.5

ISO 4766:2011 slotted set screws with flat point (ex DIN 551), mm. Slotted cone, dog and cup points: ISO 7434, 7435 and 7436, to order.

How they hold

How Set Screws Hold & How to Hold Better

Friction and bite, or a positive seat. A cup point grips by friction and by cutting into the shaft; a dog point sits in a drilled hole and cannot slip.

A set screw holds by the force its point puts on the shaft. That force comes from the tightening torque, so the key, the socket and the point all matter: a hardened, fully engaged socket lets you reach the specified torque.

For cone points on hard shafts (above about HRC 15), spot the shaft to half the cone depth first. Where two set screws are used in a collar, their positions relative to each other change the holding power.

Do	Avoid
Full key engagement, correct key	Worn or undersized keys
Ground flat or drilled spot	Point on a round, hard shaft
Hardened screw on a softer shaft	Same hardness: little bite
Thread locker or nylon patch	Re-using a damaged screw

DIN, ISO & inch

DIN 913–916, ISO 4026–4029 & ASME B18.3 Compared

Point	Old DIN	ISO	Slotted ISO	Inch
Flat	DIN 913	ISO 4026	ISO 4766 (ex DIN 551)	ASME B18.3 flat
Cone	DIN 914	ISO 4027	ISO 7434	ASME B18.3 cone
Dog	DIN 915	ISO 4028	ISO 7435	ASME B18.3 half dog
Cup	DIN 916	ISO 4029	ISO 7436	ASME B18.3 cup

The ISO point diameters are the old DIN maximum values, so ISO and DIN screws interchange. ISO 4028 adds a short dog point next to the long DIN 915 dog, and ISO 4027 cone points up to M5 have a slightly larger flat tip than DIN 914.

Inch socket set screws to ASME B18.3 take inch keys, and the cone point angle changes with length: 90° from length Y up, 118° on shorter screws, for example from 0.31″ on a 1/4″ screw.

Finder

Set Screw Finder: Key, Point & Torque

Pick metric or inch, the size, the point and the length to get the key, socket depth, point dimensions, tap drill and, for inch, the tightening torque.

Your set screw

System

Size

Point

Length, mm

Dimensions from ISO 4026–4029 and ASME B18.3-2003 (alloy steel). Tap drill: metric d − P; inch about 75 % thread. Inch torque is the chart’s tightening (test) torque; for stainless or soft shafts use less.

Result

4

mm hex key

5

mm cup d_z max

Socket depth:3–5 mm min (by length)

Point detail:cup point

Tap drill:6.8 mm

Torque:maker’s figure

Standard:ISO 4029 (DIN 916)

Materials

Set Screw Materials & Finishes

Material	Class	Finish	Best for
Alloy steel	45H (ISO 898-5); inch HRC 45–53	Black oxide, zinc	Highest holding power
Stainless A1 / A2	12H / 21H (ISO 3506-3)	Plain, passivated	Food, packaging, wet areas
Stainless A4	12H / 21H (ISO 3506-3)	Plain, passivated	Marine and chemical plant
Brass	To order	Plain	Soft shafts, instruments

Alloy steel

45H

Hardened, black oxide.

4140

Stainless A1

303

Free machining.

303

Stainless A2

304

As in the photo.

304

Stainless A4

316

Chlorides and washdown.

316

Manufacturing

How Our Set Screws Are Made

1

Wire

Alloy or stainless wire, certified by heat.

2

Cold forming

Hex socket and point formed in the header.

3

Thread rolling

Full-length thread rolled.

4

Hardening

Steel screws quenched and tempered to 45H.

5

Finishing

Black oxide, zinc or passivation; nylon patch option.

6

Inspection

Socket, point, thread and hardness checked.

Applications

Where Our Set Screws Are Used

Gears & pulleys

Locking hubs to shafts.

Shaft collars

Stops and spacers on shafts.

Couplings

Motor and pump couplings.

Knobs & handles

Fixing control knobs to spindles.

Adjusters & stops

Fine adjustment and end stops.

Instruments

Miniature sizes from M1.6.

Quality & testing

Set Screw Inspection & Certification

Check	Method	Applied to
Hex socket	GO / NO-GO socket gauges, depth t / T	Every lot
Point	Optical comparator: d_p, d_z, z	Every lot
Thread	Ring gauges	Every lot
Hardness	Vickers / Rockwell	Steel lots
Torsion	Test torque, socket must not ream	Inch lots, on request
Material	PMI / chemical analysis	Stainless lots

Every shipment includes

Mill certificate with heat number
Dimensional and hardness report
Lot number on every box

On request

EN 10204 3.1 certificate
Torsion test report
Nylon patch or thread locker pre-applied

FAQ

Set Screw Questions, Answered

A headless screw, threaded along its whole length, that is tightened in a tapped hole until its point presses on a part, typically to lock a pulley, gear or collar to a shaft. Socket set screws, also called grub screws, are turned with a hex key: ISO 4026 to 4029 in metric and ASME B18.3 in inch.

Cup point (ISO 4029) for general locking on shafts, where the edge bites in. Flat point (ISO 4026) for frequent adjustment and least damage, best against a ground flat. Cone point (ISO 4027) for permanent setting in a drilled spot. Dog point (ISO 4028) to enter a hole or slot for positive location. Inch screws also come with oval and half dog points.

A 4 mm key. Set screws take smaller keys than cap screws of the same thread: M6 takes 3 mm, M10 5 mm and M12 6 mm. In inch sizes, 1/4 in takes 1/8 in, 3/8 in takes 3/16 in and 1/2 in takes 1/4 in.

DIN 913, 914, 915 and 916 were replaced by ISO 4026 (flat point), ISO 4027 (cone), ISO 4028 (dog) and ISO 4029 (cup). The point diameters equal the old DIN maximum values; ISO 4028 adds a short dog point, and cone points up to M5 have a slightly larger truncated tip.

For inch alloy steel socket set screws, the ASME B18.3 chart lists tightening (test) torques of 77.9 lb-in for 1/4 in, 273 lb-in for 3/8 in and 615 lb-in for 1/2 in; the socket must take that torque without reaming. For metric screws, use the maker's figures for the property class and the shaft hardness.

Steel metric socket set screws are property class 45H to ISO 898-5, at least 450 HV; inch alloy steel socket set screws are hardened to Rockwell C45 to 53. Stainless set screws to ISO 3506-3 are classes 12H and 21H, which are softer, so they bite less and hold less.

Long enough for full thread engagement and key engagement. In ISO the minimum socket depth rises with length: for M8 from 3 mm on short screws to 5 mm on longer ones. ASME B18.3 lists the shortest length that gets the full key engagement T, for example 0.25 in for a 1/4 in cup point screw.

Hardened alloy steel (45H, black oxide), and A1, A2 and A4 stainless steel like the screws in our photo. Brass and other materials are made to order for special needs.