Hex Socket Set Screws (Grub Screws): Flat Point vs Cone Point vs Dog Point vs Cup Point

DIN 912 and ISO 4762 Socket Head Cap Screws: A Comparison

DIN 913-916 and ISO 4026-4029 explained (with sourcing tips that save time and headaches)

Socket set screws, often nicknamed grub screws, are small parts that do big work. They lock collars, pulleys, gears, knobs, and couplings onto shafts, and they do it in tight spaces where a headed fastener won’t fit.

But here’s the catch: the point style you choose changes how the screw holds, how repeatable the assembly is, and how much damage you do to the mating surface. And if you’re buying metric, you’ll usually see these parts specified under either DIN or ISO standards.

This guide breaks down the four most common hexagon socket set screw types and their DIN/ISO equivalents, along with the small-but-important differences that affect availability, pricing, and lead times.

The quick DIN to ISO cross-reference

If you remember nothing else, remember this:

• DIN 913 = ISO 4026 = Flat point
• DIN 914 = ISO 4027 = Cone point
• DIN 915 = ISO 4028 = Dog point (full or half depending on length per standard)
• DIN 916 = ISO 4029 = Cup point

In most real-world sourcing scenarios, DIN and ISO versions are functionally interchangeable, but point style and a few standard changes can affect what’s available today.

What are hex socket set screws?

A hex socket set screw is a headless, fully threaded screw with an internal hex drive. Instead of clamping two parts with a head, it uses its point to press into (or locate against) another component, usually a shaft.

That means the end geometry (flat, cone, dog, cup) is the star of the show.

The “Big 4” point styles: what they are and when to use them

1) Flat Point (DIN 913 / ISO 4026)

What it is: A blunt, flat end that presses against the surface.

Best for:

• Holding against a flat (a machined flat on a shaft)
• Applications where you want less surface damage
• Assemblies that need adjustment or repositioning

What to expect:
Flat points spread force over a larger area, which can reduce marring—but may not “bite” as aggressively on a smooth round shaft.

2) Cone Point (DIN 914 / ISO 4027)

What it is: A sharp, pointed end designed to penetrate.

Best for:

• When you want maximum holding power
• Semi-permanent assemblies where movement is not acceptable
• Harder-to-lock setups where the screw must dig in

What to expect:
Cone points are excellent for grip… and excellent at leaving a mark. If you’re trying to preserve the shaft surface, cone points may not be your friend.

3) Dog Point (DIN 915 / ISO 4028) – Half Dog vs. Full Dog Depending on Length per Standard

What it is: A cylindrical “nose” that extends from the end. Instead of biting in, it often locates into a hole, slot, or feature on the mating part.

Best for:

• Assemblies where repeatable positioning matters
• Designs with a drilled hole or slot in the shaft for positive location
• When you want a more “mechanical stop” feel instead of pure friction

The important part: half dog vs. full dog isn’t arbitrary

DIN 915 / ISO 4028 can be half dog or full dog, and which one you get is determined by the length of the screw, per the standard.

Example (M8 DIN 915):

• At lengths ≤ 10 mm: typically half dog

• • • Dog length (z) ≈ 2.0–2.25 mm

• At lengths > 10 mm: typically full dog

• • Dog length (z) ≈ 4.0–4.3 mm

That means two “DIN 915” screws can behave differently depending on length.

Pro tip for buyers and engineers:
If you need a full dog point at a short length (or the reverse), you may need to submit a special production request specifying the dog length, as it won’t be standard at that size/length combination.

4) Cup Point (DIN 916 / ISO 4029)

What it is: A concave end with a “cup” indentation.

Best for:

• General-purpose locking on round shafts
• Strong holding without the extreme penetration of a cone point
• A reliable “default” in many industrial applications

What to expect:
Cup points grip well and are widely used. They can still mark the shaft, but generally not as aggressively as cone points.

Drive depth (“t min.”): a small spec that can cause big frustration

On drawings and spec sheets, drive depth is often shown as t min. (minimum socket depth). This depth is not one-size-fits-all, it varies with diameter and length.

Using the same M8 DIN 915 example:

• Lengths ≤ 10 mm: drive depth (t min.) ≈ 3 mm
• Lengths > 10 mm: drive depth (t min.) ≈ 5 mm

Why you care:

• Shallow socket depth can affect tool engagement
• Tool engagement affects torque
• Torque + shallow engagement can increase the risk of stripping

If you’ve ever had a set screw that “should have worked” but kept rounding out, socket depth is one of the first things worth checking.

Material notes: what’s “standard” vs what becomes non-standard

For alloy steel versions, these set screws are typically produced in a quenched and tempered steel, often referenced in standards context as 45H steel.

If you request a different alloy steel class while still referencing a DIN/ISO standard, that often becomes a non-standard item, which can impact:

• lead time
• minimum order quantities
• pricing
• ability to source quickly

If you’re not sure what you actually need, it’s usually faster (and cheaper) to confirm the application first, shaft material, torque/vibration, environment, and whether surface marking is acceptable.

How to choose the right set screw point style (fast decision guide)

If you need…

• Less surface damage / adjustment-friendly → Flat point (DIN 913 / ISO 4026)
• Maximum bite / strongest lock → Cone point (DIN 914 / ISO 4027)
• Repeatable locating into a hole/slot → Dog point (DIN 915 / ISO 4028), confirm half vs. full dog
• Strong general-purpose locking on round shafts → Cup point (DIN 916 / ISO 4029)

And when in doubt, tell your supplier what you’re locking onto (round shaft vs flat vs drilled hole) and what you’re trying to prevent (slip, rotation, vibration loosening, repositioning).

Sourcing tip: when “standard” still isn’t simple

Dog points are the biggest gotcha because of the half vs. full dog distinction. If your assembly requires a specific dog length and you’re right on the edge of standard ranges, the fastest path is often:

1. Confirm the required dog length (z)
2. Confirm the socket depth requirement (t min.)
3. Decide whether standard works, or if it needs special production

That up-front clarity prevents reorders, line delays, and “we got the right part number but it doesn’t behave the same” surprises.

Eurolink freight options: match the shipping speed to the urgency

If you’re chasing downtime, prototype builds, or urgent replenishment, freight timing matters. Eurolink supports multiple freight speeds so you can balance timeline and cost:

• FAST: Each month, we ship out one consolidated sea freight shipment from Europe that arrives at our U.S. facility within 6-8 weeks of shipping. This is our most affordable FAST shipping option from Europe.
• FASTER: Each Wednesday, we ship out one consolidated air freight shipment from Europe that arrives at our U.S. facility within 1-2 weeks of shipping. This speeds up delivery when you need it FASTER.
• FASTEST: On request, we also offer an Express air freight option that normally ships from Europe within 24-48 hours after an order is placed and arrives at our U.S. facility within 3-5 business days. This is our FASTEST option from Europe.

If you’re not sure which option fits your schedule, Eurolink’s team can talk through your timeline and recommend the best route.

Hex Socket Set Screws FAQs

What are the four major types of socket set screws?

The four most common types are flat point, cone point, dog point, and cup point, standardized as DIN 913-916 and ISO 4026-4029.

Are DIN and ISO set screws interchangeable?

For these “Big 4” families, they are generally interchangeable in practice. Key differences: ISO omits certain diameters (M1.4, M1.8, M14, M18, M22) and ISO includes stainless options (A2, A4).

What’s the difference between half dog point and full dog point?

A half dog has a shorter, cylindrical nose than a full dog. The standard determines half vs full based on length. For example, many M8 dog point set screws are half dog at ≤10 mm length and full dog above 10 mm.

What does “t min.” mean on a set screw spec sheet?

“t min.” typically refers to the minimum socket drive depth. It can vary by diameter and length, affecting tool engagement and stripping risk.

Which set screw point is best for a round shaft?

A cup point (DIN 916 / ISO 4029) is a common choice for round shafts because it grips reliably without the aggressive penetration of a cone point.

Need help quoting or confirming the right standard?

If you’re ordering DIN/ISO socket set screws and want to avoid delays, especially with dog point lengths or uncommon diameters, Eurolink can help you confirm point style, material, and freight timing so you get what you need, when you need it.