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Russian ISO4766 Slotted Flat Point Set Screw | Full Specifications, Dimensions & Guide
ISO4766 (DIN551 equivalent) defines the slotted flat point set screw standard — M1.2 to M12, screwdriver drive, non-damaging flat point. This guide covers every dimension, material grade, and DIN551 equivalence you need for correct specification and sourcing.
What Is an ISO4766 Slotted Flat Point Set Screw?
ISO4766 is the international standard for slotted headless set screws with a flat, non-damaging point, covering metric coarse thread M1.2–M12 with a screwdriver-slot drive.
DIN551 = ISO4766 = DIN EN 24766. All three designations specify the same product. DIN551 is the legacy German standard officially superseded by ISO4766 — parts marked either way are fully interchangeable with identical dimensions, tolerances, and product grade A classification per ISO 4759-1.
The defining feature of ISO4766 is its straight screwdriver slot cut across the top face — the fundamental engineering difference from DIN913 (ISO4026), which uses a hex socket drive. Both standards produce a flat point that applies friction/pressure to the mating shaft without damaging it. The drive, hardness grade, and size range are what differ.
Latest revision: ISO4766:2024 (previously ISO4766:2011, ISO4766:1983). Product grade A. Thread range: M1.2–M12 coarse pitch only.
ISO4766 vs DIN913 — Slotted vs Hex Socket Flat Point
Both ISO4766 and DIN913 deliver a flat point — the critical differences are the drive type, hardness grade (14H vs 45H), and maximum available size (M12 vs M24+).
| Feature | ISO4766 / DIN551 (Slotted) | DIN913 / ISO4026 (Hex Socket) |
|---|---|---|
| Drive Type | Straight screwdriver slot | Hex socket (Allen key) |
| Drive Tool | Flat-blade screwdriver | Hex key / Allen wrench |
| Size Range | M1.2 – M12 only | M1.6 – M24+ |
| Point Shape | Flat, non-damaging | Flat, non-damaging |
| Point Function | Identical — friction/pressure contact | Identical |
| Access in Confined Spaces | Limited (screwdriver needs axial clearance) | Better (L-key fits smaller radial clearance) |
| Tamper Resistance | Low (common screwdriver) | Medium (requires hex key) |
| Typical Industry Use | Light-duty instruments, small appliances, legacy designs | General mechanical engineering, precision machinery |
| Hardness Grade | 14H (lower than DIN913 45H) | 45H |
| Maximum Size Available | M12 | M24+ |
| DIN Equivalent | DIN551 (superseded) | DIN913 (current) |
Note: For M12 and below where a slotted drive is acceptable, either standard produces the same flat point function. Choose DIN913 for higher strength or larger sizes.
ISO4766 Full Dimensions Table (M1–M12)
All dimensions per ISO4766:2011 / ISO4766:2024, product grade A. dp = flat point diameter; n = slot width; t = slot depth. Screwdriver blade width must not exceed n max.
| Thread d | Pitch P (mm) | Face Dia. df | dp max (mm) | dp min (mm) | n nom (mm) | n min (mm) | n max (mm) | t max (mm) | t min (mm) |
|---|---|---|---|---|---|---|---|---|---|
| M1* | 0.25 | ≈ minor dia | 0.50 | 0.25 | 0.20 | 0.26 | 0.40 | 0.52 | 0.40 |
| M1.2 | 0.25 | ≈ minor dia | 0.60 | 0.35 | 0.20 | 0.26 | 0.40 | 0.52 | 0.40 |
| M1.4 | 0.30 | ≈ minor dia | 0.70 | 0.45 | 0.20 | 0.26 | 0.40 | 0.63 | 0.48 |
| M1.6 | 0.35 | ≈ minor dia | 0.80 | 0.55 | 0.25 | 0.31 | 0.45 | 0.74 | 0.56 |
| M2 | 0.40 | ≈ minor dia | 1.00 | 0.75 | 0.25 | 0.31 | 0.45 | 0.84 | 0.64 |
| M2.5 | 0.45 | ≈ minor dia | 1.50 | 1.25 | 0.40 | 0.46 | 0.60 | 0.95 | 0.72 |
| M3 | 0.50 | ≈ minor dia | 2.00 | 1.75 | 0.40 | 0.46 | 0.60 | 1.05 | 0.80 |
| (M3.5)* | 0.60 | ≈ minor dia | 2.20 | 1.95 | 0.50 | 0.56 | 0.70 | 1.21 | 0.96 |
| M4 | 0.70 | ≈ minor dia | 2.50 | 2.25 | 0.60 | 0.66 | 0.80 | 1.45 | 1.12 |
| M5 | 0.80 | ≈ minor dia | 3.50 | 3.20 | 0.80 | 0.86 | 1.00 | 1.63 | 1.28 |
| M6 | 1.00 | ≈ minor dia | 4.00 | 3.70 | 1.00 | 1.06 | 1.20 | 2.00 | 1.60 |
| M8 | 1.25 | ≈ minor dia | 5.50 | 5.20 | 1.20 | 1.26 | 1.51 | 2.50 | 2.00 |
| M10 | 1.50 | ≈ minor dia | 7.00 | 6.67 | 1.60 | 1.66 | 1.91 | 3.00 | 2.40 |
| M12 | 1.75 | ≈ minor dia | 8.50 | 8.14 | 2.00 | 2.06 | 2.31 | 3.60 | 2.80 |
Notes:
• df ≈ minor thread diameter (face diameter, not separately specified in ISO4766)
• dp = flat point diameter — the smooth ground contact face at the screw tip
• n = slot width — screwdriver blade must not exceed n max to avoid burring the slot
• t = slot depth — screwdriver blade engagement depth
• M1* and (M3.5)* are non-preferred sizes — confirm availability with your supplier
• ISO4766:2024 official range: M1.2 to M12. M1 available from some suppliers under DIN551 legacy spec
• All screws are fully threaded — nominal length = total screw length
All three designations specify the same slotted flat point set screw with identical dimensions and tolerances. DIN551 is the legacy German standard — accept DIN551-labeled parts when sourcing ISO4766. Both are fully interchangeable with identical dimensions, thread pitch, and product grade A tolerances.
Materials & Hardness Grades
| Material | Grade | Typical Application |
|---|---|---|
| Carbon Steel | 14H | Light fixtures, appliances, instrument panels |
| Stainless A1 (303) | — | Corrosion-resistant light assembly, food equipment |
| Stainless A2 (304) | A2 | General corrosion resistance, mild chemical exposure |
| Stainless A4 (316) | A4 | Marine, harsh chemical, outdoor environments |
Important: ISO4766 carbon steel is 14H — significantly softer than the 45H used in DIN913 hex socket set screws. For higher clamping force or hard shaft materials, use DIN913 hex socket flat point set screws instead.
Key Applications
- Small instrument and scientific equipment assembly (M1.2–M4)
- Consumer electronics and small appliance adjustment screws
- Furniture fittings and cam lock mechanisms
- Optical instrument focus and position locks
- Hobby, model making, and RC equipment (M2–M4)
- Legacy machinery maintenance — replacing worn DIN551 screws
- Electrical equipment terminal and cable retainer applications
- Light-duty shaft collar and knob retention (low torque only)
ISO4766 in the Slotted Set Screw Family
ISO4766 is one of four slotted headless set screw standards. Each uses a screwdriver drive but a different point geometry for different retention applications. All carry the same 14H hardness grade and are generally smaller and lighter-duty than the parallel hex socket family (DIN913/914/915/916).
| Standard | Drive | Point Type | DIN Equivalent | Size Range |
|---|---|---|---|---|
| ISO4766 / DIN551 | Slotted | Flat point | DIN551 | M1.2–M12 |
| ISO7434 / DIN417 | Slotted | Half dog (short dog) | DIN417 | M3–M12 |
| ISO7435 / DIN438 | Slotted | Full dog (long dog) | DIN438 | M4–M20 |
| ISO7436 / DIN553 | Slotted | Cone point | DIN553 | M3–M12 |
The slotted set screw family (ISO4766/7434/7435/7436) runs parallel to the hex socket family but uses a screwdriver drive, carries softer 14H hardness, and covers smaller maximum sizes. Choose by point geometry first (flat/dog/cone), then confirm the drive and hardness meet your application requirements.
How to Order ISO4766 — Specification Format
Standard ordering format follows the ISO fastener designation convention:
Set Screw ISO4766 – M6 × 10 – 14H
Where: M6 = nominal thread diameter | 10 = nominal length in mm (total length — fully threaded) | 14H = hardness class for carbon steel
For stainless: Set Screw ISO4766 – M6 × 10 – A2
Legacy equivalents accepted by all suppliers:Set Screw DIN551 – M6 × 10Set Screw DIN EN 24766 – M6 × 10
Slot width note: Specify that your screwdriver blade must not exceed n max (see dimensions table) — a blade that is too wide will burr the slot, especially in the softer 14H carbon steel.
Frequently Asked Questions About ISO4766
Need ISO4766 / DIN551 Set Screws in Bulk?
we supply ISO4766 slotted flat point set screws (DIN551 equivalent) in carbon steel 14H and stainless A1/A2/A4. Sizes M1.2–M12, custom lengths available. MOQ from 500 pcs.