Set Screws
What are set screws?
Set screws are headless fasteners designed to lock components in place—most often securing a collar, gear, or pulley to a shaft. With the drive recessed into the body and no external head, they sit at or below the surface for a clean, low-profile hold in tight spaces.
Which point styles do set screws come in?
- Cup point — general-purpose point that bites into the shaft for strong holding power.
- Knurled cup point — serrated edge increases grip and resists loosening under vibration.
- Flat point — flat bearing surface for frequent adjustment or where you want to minimize shaft marking.
- Cone point — sharp tip for precise location; penetrates the mating surface for maximum holding strength.
- Dog point — cylindrical tip fits into a prepared hole or slot for positive indexing.
- Half-dog (extended flat) point — shorter dog for shallow holes/slots; easier assembly alignment.
- Soft/nylon/brass tip — protects finished shafts while maintaining friction.
What drive styles do set screws use?
- Hex-socket (Allen) — the most common for high torque in tight spaces.
- Slotted — simple service with a flat screwdriver.
- Square / hex socket / Torx® — specialty drives used on select sizes for added torque or security.
Materials and finishes for set screws
- Alloy steel black oxide — high strength with low-glare finish for indoor use.
- 18-8 / 304 stainless steel — corrosion resistance for most environments.
- 316 stainless steel — added resistance in marine or chloride exposure.
- Brass / nylon-tip combinations — protect soft or finished shafts.
How do I size and specify set screws?
Order by diameter × thread × length (e.g., 1/4″-20 × 3/8″, 10-32 × 1/4″, M6-1.0 × 8 mm). Length is the overall screw length. Choose the point style, drive, and material/finish to match the shaft and environment.
When should I use each set screw point style?
- Cup / knurled cup — general machinery, pulleys, collars; good holding strength.
- Flat — frequent repositioning or against a flat machined spot; minimizes marring.
- Cone — precise location or where penetration into the mating part is acceptable.
- Dog / half-dog — alignment in a detent hole or slot; positive indexing.
- Soft-tip — protect chromed, ground, or soft shafts.
Common applications for set screws
- Securing collars, gears, sprockets, and pulleys to rotating shafts
- Locating knobs, levers, and handles on flats
- Locking components in instruments, appliances, and fixtures
- Assembly of jigs, tooling, and precision mechanisms
Installation tips for set screws
- Match the point style to the shaft: use a machined flat for flat points; a detent hole for dog/half-dog; avoid marking critical surfaces unless specified.
- Use the correct hex key and seat fully to prevent stripping; tighten to the recommended torque for the size/material.
- Apply a suitable threadlocker or use a second “jam” set screw when vibration is present.
- Do not over-torque—excess force can deform threads or damage the shaft.
Set Screws FAQs
See the accordion below for quick answers on point selection, sizing, torque, thread standards, and ways to protect or lock a shafted assembly.
Note — Guidance here is general. Always follow the product datasheet and your project specifications.
To lock or locate components on a shaft or inside a recess—e.g., securing collars, gears, pulleys, or knobs.
Cup grips most shafts; knurled cup adds bite under vibration; flat protects flats and allows adjustment; cone penetrates for precise location; dog/half-dog index into a hole or slot for positive positioning.
Use a machined flat with a flat point, or select soft/nylon/brass-tip screws. Avoid cone points on finished surfaces unless specified.
Overall length end-to-end. Order as diameter × thread × length (e.g., 1/4″-20 × 3/8″ or M6-1.0 × 8 mm).
Inch UNC/UNF (e.g., 10-32, 1/4″-20) and metric ISO (e.g., M3–M12). Match the tapped hole or part spec.
Often recommended where vibration exists. Alternatively, use a second jam set screw or a knurled-cup point for added resistance.
Follow torque guidance for the size/material. Tighten until secure; avoid over-torque that can deform threads or mark the shaft.
When the part has a hole/slot and you need repeatable indexing or anti-rotation.
Use alloy steel black oxide for high strength in dry interiors; 18-8/304 for general corrosion resistance; 316 for marine/chemical exposure.
Yes, if the threads and drive are intact and the point isn’t deformed. Replace any screw with damaged threads, rounded sockets, or flattened points.