Stainless Steel Allen Hex Set Grub Screw Assortment – M3/M4/M5/M6/M8 Cup Point, 250pcs

A comprehensive assortment of A2 stainless steel hex socket set screws (grub screws) in the five most commonly used metric sizes: M3, M4, M5, M6, and M8. Cup point geometry provides positive grip on shaft surfaces without the shaft damage associated with cone or dog point screws. Supplied in a segmented plastic storage box for organized access on the workbench or in the field.

Key Specifications

• Standard: DIN 916 / ISO 4029 (hex socket cup point set screw)
• Material: A2 stainless steel (304 SS / 18-8) — corrosion resistant
• Drive: Hex socket (Allen key / hex wrench)
• Point Style: Cup point — shallow cup indent grips shaft without deep penetration
• Sizes Included: M3, M4, M5, M6, M8 (multiple lengths per size)
• Total Quantity: 250 pieces
• Thread: Metric coarse pitch (M3×0.5, M4×0.7, M5×0.8, M6×1.0, M8×1.25)
• Hardness: A2-70 (700 MPa tensile strength)
• Storage: Segmented plastic box with labeled compartments

Cup Point vs Other Set Screw Point Styles

Set screws are available in multiple point geometries. Choosing the wrong point style causes shaft damage or inadequate holding force:

• Cup point (this product): Most common. The shallow cup rim bites into the shaft surface for positive grip. Leaves a small circular mark but does not deeply gouge. Best for general-purpose shaft locking where occasional repositioning is needed.
• Cone point: Tapered point penetrates deeply into a pre-drilled dimple on the shaft. Maximum holding force. Permanent or semi-permanent applications only — difficult to remove without shaft damage.
• Flat point: No penetration. Used on hardened shafts or where zero shaft marking is required. Lower holding force — relies on friction only.
• Dog point (half-dog): Cylindrical stub that locates into a drilled hole in the shaft. Provides positive angular and axial location. Used in precision indexing applications.
• Oval point: Rounded tip for use against soft materials or where repeated adjustment is needed without shaft damage.

What Questions Does This Product Answer?

• "What size Allen key do I need for M4 set screws?" — M4 DIN 916 uses a 2mm hex key. M3=1.5mm, M5=2.5mm, M6=3mm, M8=4mm.
• "Can I use stainless steel set screws on a steel shaft?" — Yes, but note that A2 SS (304) is softer than hardened steel shafts. For high-torque applications on hardened shafts, consider Grade 12.9 alloy steel set screws instead.
• "What is the difference between a set screw and a grub screw?" — They are the same fastener. "Set screw" is the North American term; "grub screw" is the British/Australian term. Both refer to a headless screw driven entirely below the surface.
• "How tight should I torque an M6 set screw?" — Typical torque for M6 A2 SS cup point: 4–6 Nm. Always use a calibrated torque wrench for precision applications; over-tightening strips the hex socket.

Typical Applications

• CNC & machining: Locking pulleys, sprockets, and gears to motor shafts; securing tool holders and collet nuts
• 3D printing: Locking GT2 pulleys and drive gears to stepper motor shafts (M3 most common)
• Shaft collars & couplings: Securing flexible shaft couplings, encoder discs, and bearing collars
• Robotics & automation: Locking servo horn adapters, lead screw nuts, and linear rail carriages
• Marine & outdoor: A2 stainless resists salt spray and moisture — suitable for marine hardware, outdoor enclosures, and garden equipment

A2 vs A4 Stainless Steel — Which Do You Need?

• A2 (304 SS): Standard stainless. Excellent corrosion resistance in most environments. Not suitable for continuous saltwater immersion or chlorinated environments.
• A4 (316 SS): Marine-grade stainless. Contains molybdenum for superior resistance to chlorides and saltwater. Required for offshore, coastal, and chemical processing applications.

Package Contents

250 pieces total — M3, M4, M5, M6, M8 stainless steel hex socket cup point set screws in assorted lengths, supplied in labeled plastic storage box.