Shoulder Bolt
Bolts · shoulder screw · stripper bolt · precision shoulder screw
Definition: A shoulder bolt has a precision-ground, unthreaded shoulder of larger diameter than the thread, so it can act as a pivot, axle, or locating pin.
Anatomy
■ Head■ Shank■ Threads■ Point
Governing standards: ASME B18.3
Common Sizes
| Inch | Metric | Head width | Head height |
|---|---|---|---|
| 1/4 shoulder | M6 shoulder | 3/8 | #10-24 thread |
| 5/16 shoulder | M8 shoulder | 7/16 | 1/4-20 thread |
| 3/8 shoulder | M10 shoulder | 9/16 | 5/16-18 thread |
Representative sizes. Full dimensional data lives in the standards listed below.
Grades & Strength
| Grade | Material | Tensile (psi) | Marking |
|---|---|---|---|
| Alloy steel | alloy steel, heat-treated | 140,000 | None |
| 303 / 316 stainless | stainless steel | 70,000 | None |
Materials
- Alloy steel (black oxide)
- Stainless steel 303 / 316
Pros & Cons
Pros
- Accurate locating and smooth rotation
- Ground shoulder gives a precise bearing surface
- Head retains the assembly
Cons
- Not designed for clamping loads
- Specialty item — pricier than a standard bolt
- Shoulder length must be chosen carefully
Typical Uses
- Pivot points and axles
- Guide pins in dies
- Stripper plates in stamping
- Pulleys, gears, and cams
Alternatives & Related
- Clevis Pin — Simpler pivot pin retained with a cotter pin
- Socket Head Cap Screw — Standard high-strength screw for clamping
Where to Buy
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FAQ
What is a shoulder bolt used for?
Anything that needs a smooth, accurately sized shaft that rotates or slides — pivots, axles, guide pins, and locating features. The threaded end only retains it.
How do I size a shoulder bolt?
Match the shoulder diameter and length to the bearing or bore, and choose the thread size to suit the tapped hole. Do not use the shoulder as a clamp.