Choosing the Correct Set Screw for Your Job: DIN 913, 914, 915, 916, 551 & 553
Set screws, also called grub screws or blind screws, hold a hub, collar, pulley, gear, knob, or another component against a shaft. Because they have no conventional head, the point and drive determine how the screw contacts the mating part. This guide compares six metric styles sold by Metric Screw & Tool Company. DIN designations remain common ordering terms; check the drawing and product listing before specifying a replacement.
AT A GLANCE: CHOOSE BY POINT AND DRIVE
DIN 913 — flat point, internal hex: broad flat contact; helpful when limiting shaft marks or allowing adjustment matters.
DIN 914 — cone point, internal hex: pointed contact can bite into the shaft for a more positive, often semi-permanent hold.
DIN 915 — dog point, internal hex: cylindrical pilot enters a matching hole or slot for repeatable positioning.
DIN 916 — cup point, internal hex: concave tip grips the surface; a common general-purpose choice for shaft-mounted parts.
DIN 551 — flat point, slotted drive: flat-point contact with a screwdriver slot for designs specifying a slotted drive.
DIN 553 — cone point, slotted drive: cone-point contact with a screwdriver slot for designs specifying that format.
DIN 913: FLAT-POINT SOCKET SET SCREW
DIN 913 uses a flat point and internal hex drive; its related ISO designation is 4026. The flat end spreads contact more than a sharp point, which helps limit concentrated marking. Consider it when you may reposition or remove the assembly, when the shaft should stay in better condition, or when the screw bears against a machined flat. It still needs adequate clamping force and a suitable mating surface; “flat point” does not mean it cannot slip.
DIN 914: CONE-POINT SOCKET SET SCREW
DIN 914 has a cone point and internal hex drive; its related ISO designation is 4027. The sharp cone is intended to press into the mating surface, helping resist movement when tightened. Choose it for a more fixed position when an indentation is acceptable or the design provides a prepared seat. Avoid it where shaft finish must remain pristine or frequent adjustment is expected.
DIN 915: DOG-POINT SOCKET SET SCREW
DIN 915 has a cylindrical dog point and internal hex drive; its related ISO designation is 4028. The projecting pilot is meant to enter a matching drilled hole, groove, or locating feature. This provides repeatable alignment and can help locate a hub without relying only on friction. Match the hole diameter, depth, and location to the dog point, and make sure the pilot does not bottom out before the screw clamps as intended.
DIN 916: CUP-POINT SOCKET SET SCREW
DIN 916 has a concave cup point and internal hex drive; its related ISO designation is 4029. The rim of the cup grips the mating surface when tightened, so it is often a practical all-around choice for collars, pulleys, and similar shaft-mounted parts. It can mark the shaft, and results depend on shaft material, hardness, finish, and installation torque. Choose another style if easy repositioning or positive location in a prepared hole is required.
DIN 551: SLOTTED FLAT-POINT SET SCREW
DIN 551 pairs a flat point with a slotted screwdriver drive; its related ISO designation is 4766. Its contact behavior resembles the flat-point DIN 913, but the drive is different. Use DIN 551 when the slotted drive is required by an existing design, a screwdriver can reach the installation, or matching legacy equipment matters. A slot can cam out more readily than a well-engaged internal hex, so do not assume it suits high installation torque.
DIN 553: SLOTTED CONE-POINT SET SCREW
DIN 553 pairs a cone point with a slotted screwdriver drive; its related ISO designation is 7434. Choose it when you need cone-point contact and the slotted format is specified or provides workable tool access. The point can indent the shaft, and the slot limits how confidently you can apply torque compared with a suitable hex-key drive. Consider DIN 914 when you want cone-point contact with an internal-hex drive.
HOW TO CHOOSE THE RIGHT TYPE FOR THE JOB
1. Decide what the point must do. Use a flat point when surface protection and adjustment matter; a cup or cone point when you want the tip to bite; a dog point when a matching hole or slot provides the location.
2. Consider whether the assembly will move or be adjusted. A pointed screw can leave a mark or seat that affects later positioning. For frequent service, consider a flat point against a prepared flat or a replaceable contact feature.
3. Check the drive and access. Internal hex drives fit tight spaces and give positive tool engagement when the key is fully seated. Slotted drives may suit a legacy design but are easier to damage under excessive torque.
4. Match the full specification. Confirm thread diameter and pitch, length, point geometry, material, hardness, finish, corrosion environment, temperature, and installation space. A standard number alone does not specify every application requirement.
5. Follow the equipment drawing or manufacturer’s torque guidance, use the correct tool, and do not treat a set screw as a tensile-load fastener. Check the selected screw and mating parts for actual service conditions.
QUICK DECISION GUIDE
Protect a shaft or allow adjustment: start with DIN 913 or DIN 551.
Need pointed bite with an internal-hex drive: compare DIN 914 and DIN 916.
Need repeatable alignment into a prepared feature: choose DIN 915.
Need cone-point contact with a slotted drive: choose DIN 553.
Need help matching a standard to a specific assembly? Compare the drawing, thread, point dimensions, material, and finish with the product listing, then contact Metric Screw & Tool Company for help selecting the right part.
Related ISO designations: DIN 913 / ISO 4026; DIN 914 / ISO 4027; DIN 915 / ISO 4028; DIN 916 / ISO 4029; DIN 551 / ISO 4766; DIN 553 / ISO 7434.
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