DIN 551 Slotted Grub Screws with Flat Point
DIN 551 grub (headless) set screws with slotted drive and flat point, M1 to M12 — the shallowest headless clamp that presses, not bites — with the full collected 10-size table: point diameter, slot and slot depth limits down to M1.
Last updated: 2026-11
Specifications
DIN 551 is the headless flat-point set screw: a fully threaded stub with a slot cut where the head would be, ending in a flat perpendicular point that presses squarely against the opposing surface. Because there is no head at all, the screw vanishes into the part — flush inside a collar, hub or latch — and the flat point spreads its clamp over the widest circle of any point form, leaving no more than a polished contact ring on the shaft. It is the choice where the mating surface must not be marked: stainless shafting, anodised parts, glass scales, adjustments that are re-made repeatedly. The collected table runs deeper than its dog- and cup-point siblings — down to M1 — and tabulates per size: the point diameter dp with max=nominal / min limits, the slot width n printed as Nominal with min/max limits, the slot depth t (min=nominal / max) and the pitch P. The slot is the only drive, so a correctly sized flat blade — matched to the n column — is what keeps the tiny M1–M2 slots from being chewed. Materials, property classes and finishes are not printed by the collected specification and follow the drawing callout.
| Standard | DIN 551 — slotted grub screws (headless set screws) with flat point |
|---|---|
| Series | M1 – M12 (10 sizes tabulated; extends below the dog/cup point slotted series) |
| Tabulated geometry | Per size: pitch P, point diameter dp (max=nominal / min), slot width n (Nominal / min / max), slot depth t (min=nominal / max) |
| Dimensions at M3 | dp max=nominal 2 / min 1.75; n nominal 0.4 (max 0.6 / min 0.46); t min 0.8 / max 1.05 |
| Dimensions at M6 | dp max=nominal 4 / min 3.7; n nominal 1 (max 1.2 / min 1.06); t min 1.6 / max 2 |
| Dimensions at M12 | dp max=nominal 8.5 / min 8.14; n nominal 2 (max 2.31 / min 2.06); t min 2.8 / max 3.6 |
| Point form | Flat point — full-circle contact, presses without marking the mating surface |
| Materials / strength | Not tabulated by the collected specification — per RFQ (property class and finish per drawing callout) |
| d thread size | P | n min | n max | t min | t max | d1 max |
|---|---|---|---|---|---|---|
| M 1 | 0.25 | 0.26 | 0.4 | 0.4 | 0.52 | 0.5 |
| M 1.2 | 0.25 | 0.26 | 0.4 | 0.4 | 0.52 | 0.6 |
| M 1.4 | 0.3 | 0.26 | 0.4 | 0.48 | 0.63 | 0.7 |
| M 1.6 | 0.35 | 0.31 | 0.45 | 0.56 | 0.74 | 0.8 |
| M 2 | 0.4 | 0.31 | 0.45 | 0.64 | 0.84 | 1 |
| M 2.5 | 0.45 | 0.46 | 0.6 | 0.72 | 0.95 | 1.5 |
| M 3 | 0.5 | 0.46 | 0.6 | 0.8 | 1.05 | 2 |
| M 3.5 | 0.6 | 0.56 | 0.7 | 0.96 | 1.21 | 2.2 |
| M 4 | 0.7 | 0.66 | 0.8 | 1.12 | 1.42 | 2.5 |
| M 5 | 0.8 | 0.86 | 1 | 1.28 | 1.63 | 3.5 |
| M 6 | 1 | 1.06 | 1.2 | 1.6 | 2 | 4 |
| M 8 | 1.25 | 1.26 | 1.51 | 2 | 2.5 | 5.5 |
| M 10 | 1.5 | 1.66 | 1.91 | 2.4 | 3 | 7 |
| M 12 | 1.75 | 2.06 | 2.31 | 2.8 | 3.6 | 8.5 |
- Source spanning title row carried verbatim: "Dimensions in mm - source DIN 551".
- Source spanning row carried verbatim: "Publication date: 09 - 1986".
- source grid ragged — 2/17 rows shorter than declared width 7; normalized with empty cells, carried verbatim (normalized with empty cells, carried verbatim; batch x152 acquisition)
| thread size | M 1 | M1.2 | M 1.4 | M1.6 | M2 | M2.5 | M3 | M3,5 | M4 | M5 | M6 | M8 | M10 | M12 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| nominal length l | ||||||||||||||
| 2 | 0.007 | 0.011 | 0.015 | 0.021 | ||||||||||
| 2.5 | 0.009 | 0.014 | 0.019 | 0.027 | ||||||||||
| 3 | 0.011 | 0.017 | 0.023 | 0.033 | 0.048 | 0.075 | 0.11 | 0.15 | ||||||
| 4 | 0.015 | 0.024 | 0.031 | 0.047 | 0.067 | 0.11 | 0.15 | 0.21 | 0.26 | 0.4 | ||||
| 5 | 0.4 | 0.061 | 0.068 | 0.14 | 0.2 | 0.27 | 0.34 | 0.52 | 0.72 | |||||
| 6 | 0.075 | 0.1 | 0.17 | 0.24 | 0.33 | 0.41 | 0.65 | 0.9 | 1.6 | |||||
| 8 | 0.14 | 0.23 | 0.33 | 0.45 | 0.57 | 0.9 | 1.25 | 2.3 | ||||||
| 10 | 0.42 | 0.56 | 0.72 | 1.15 | 1.6 | 3 | 4.2 | |||||||
| 12 | 0.68 | 0.87 | 1.4 | 1.95 | 3.7 | 5.2 | ||||||||
| 14 | 1.65 | 2.3 | 4.4 | 6.2 | ||||||||||
| 16 | 1.9 | 2.65 | 5.1 | 7.2 | ||||||||||
| 20 | 3.35 | 6.5 | 9.2 | |||||||||||
| 25 | 8.3 | 11.7 | ||||||||||||
| 30 | 14.2 |
- Source spanning title row carried verbatim: "DIN 551 - 1986 - ≈ weigth, in kg x1000 pcs, (ρ=7,85 kg/dm 3 ) - commercial lengths".
- source grid ragged — 1/17 rows shorter than declared width 15; normalized with empty cells, carried verbatim (normalized with empty cells, carried verbatim; batch x152 acquisition)
Materials
- Material, property class and finish specified per RFQ — the collected specification table covers geometry only
Ordering & documentation
Documents
Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.
Quotation
- The fastener family (DIN 551 Slotted Grub Screws with Flat Point) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
- Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
- Quantity per size and your target delivery date.
- Destination country, and any required documents (for example a mill test certificate) so the quote includes them.
Sample & supply
Minimum order quantity is 10,000 pieces. Stock items run 3–7 days. Quantities or variants outside the standard range are confirmed at quotation.
Storage & shipping
Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.
Frequently asked questions
Flat point (DIN 551) or cup point (DIN 438) — both are slotted set screws, so when does the point form matter?
Compare the contact geometry: the flat point bears on its full point diameter — the dp column runs close to the thread minor, e.g. 4 mm nominal at M6 — so seating torque spreads over a wide circle and the shaft surface stays essentially unmarked. The cup point shrinks that contact to a narrow rim (dz 3 mm nominal at M6) and deliberately bites in for higher rotation resistance. So the rule of thumb: DIN 551 where the point re-seats often or the surface must survive — stainless shafting, adjusted settings, soft or finished parts; DIN 438 where the joint must never slip and a witness mark is acceptable. Both share the same slot limits n and t, so the driver tooling does not change between them.
What is the MOQ and lead time for these screws?
Minimum order quantity is 10,000 pieces per item. Stocked sizes ship in 3–7 days; non-stock diameters, lengths or finishes are quoted with a confirmed schedule. Common sizes in this designation are widely stocked — confirm the exact schedule against quantity and size mix at quotation.
Related knowledge
- Thread-Forming vs Thread-Cutting vs Thread-Rolling Self-Tapping Screws: What the Evidence Settles on Base Material
- Screw Family Selection by Base Material: Wood, Machine and Self-Tapping Threads, Engagement and Coating
- Hex Bolts vs Socket Head Cap Screws: What the Evidence Settles on Strength, Clearance and Cost
Request a Quote
Get factory-direct pricing from the manufacturer.
What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support