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Dog Point Set Screw Dimensions (ISO 4028 / DIN 915, M1.6 to M24)
Guide · Updated October 28, 2026
ISO 4028 covers hexagon socket set screws with dog point (DIN 915), from M1.6 to M24. Values agree across fasten.it, the RC Fastener ISO 4028 sheet, IS 6094-3 (an Indian adoption of ISO 4028:2003) and Fuller Fasteners. Check your supplier for critical work.
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Step by step
- Read the thread: Measure the major diameter and pitch. The chart covers coarse M1.6 to M24.
- Pick the key: s is the hex key: M6 takes 3 mm, M8 4 mm, M10 5 mm.
- Drill for the dog: Drill the locating hole slightly over dp max so the dog point fits closely, like a dowel.
- Check the dog length: Short screws have the short dog z. Longer screws have the long dog, so make the hole deeper than z max.
- Tighten: Seat the key fully, then snug. Add threadlocker for vibration.
ISO 4028 dog point set screw dimensions (mm)
Columns: thread, pitch P, hex key s, dog diameter dp max and min, short dog length z max and min, long dog length z max and min, key engagement t min for short and long screws.
- Size | P | s | dp max | dp min | z short max | z short min | z long max | z long min | t min short | t min long
- M1.6 | 0.35 | 0.7 | 0.80 | 0.55 | 0.65 | 0.40 | 1.05 | 0.80 | 0.7 | 1.5
- M2 | 0.4 | 0.9 | 1.00 | 0.75 | 0.75 | 0.50 | 1.25 | 1.00 | 0.8 | 1.7
- M2.5 | 0.45 | 1.3 | 1.50 | 1.25 | 0.88 | 0.63 | 1.50 | 1.25 | 1.2 | 2
- M3 | 0.5 | 1.5 | 2.00 | 1.75 | 1.00 | 0.75 | 1.75 | 1.50 | 1.2 | 2
- M4 | 0.7 | 2 | 2.50 | 2.25 | 1.25 | 1.00 | 2.25 | 2.00 | 1.5 | 2.5
- M5 | 0.8 | 2.5 | 3.5 | 3.2 | 1.50 | 1.25 | 2.75 | 2.50 | 2 | 3
- M6 | 1 | 3 | 4.0 | 3.7 | 1.75 | 1.50 | 3.25 | 3.00 | 2 | 3.5
- M8 | 1.25 | 4 | 5.5 | 5.2 | 2.25 | 2.00 | 4.3 | 4.0 | 3 | 5
- M10 | 1.5 | 5 | 7.00 | 6.64 | 2.75 | 2.50 | 5.3 | 5.0 | 4 | 6
- M12 | 1.75 | 6 | 8.50 | 8.14 | 3.25 | 3.00 | 6.3 | 6.0 | 4.8 | 8
- M16 | 2 | 8 | 12.00 | 11.57 | 4.3 | 4.0 | 8.36 | 8.00 | 6.4 | 10
- M20 | 2.5 | 10 | 15.00 | 14.57 | 5.3 | 5.0 | 10.36 | 10.00 | 8 | 12
- M24 | 3 | 12 | 18.00 | 17.57 | 6.3 | 6.0 | 12.43 | 12.00 | 10 | 15
Worked example: M8 dog point in a shaft
An M8 dog point takes a 4 mm key, and its dog is 5.2 to 5.5 mm across. Drill the shaft about 5.6 mm. A long screw has a dog up to 4.3 mm long, so drill the hole at least 4.5 mm deep.
Common problems
- Dog will not enter: the hole is undersize or out of line, so re-drill it.
- Screw bottoms out: the hole is too shallow for the long dog.
- Screw loosens: add threadlocker.
FAQ
What is ISO 4028?
The hexagon socket set screw with dog (parallel) point. The plain cylindrical tip fits in a drilled hole or slot for permanent location, often instead of a dowel pin. DIN 915 is the older equivalent.
Short or long dog?
The standard gives a short dog for the shortest screw lengths and a long dog for the rest. Check the length on the box or measure the tip.
Dog or cone point?
A dog point carries more side load and can ride in a keyway slot. A cone point (ISO 4027) centres in a spot.
Why no e or s max/min?
Socket tolerances differ between the 1993-based charts and ISO 4028:2003 (e.g. M6 s max 3.071 vs 3.08), so they are left out.
What was skipped?
e min, s max/min and the short-length limit.
Related guides and calculators
- Slotted dog point set screws (ISO 7435)
- Slotted set screws (ISO 4766)
- Flat point set screws (ISO 4026)
- Cone point set screws (ISO 4027 / DIN 914)
- Cup point set screws (ISO 4029 / DIN 916)
- Socket head cap screws
- All free machinist calculators
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