Stainless Steel Hex Socket Head Precision Ground Metric M3 M4 For Bearing Shafts Shoulder Screws
What is a shoulder screw?
A shoulder screw is a fastener with three distinct sections. The head. A smooth ground shoulder. And a threaded end. The shoulder serves as a shaft. The thread holds it in place. This design gives you a fastener that also acts as a bearing or spacer.
Why use a shoulder screw instead of a regular bolt?
Regular bolts clamp parts together. Shoulder screws do more. The shoulder provides a precise surface for rotation. Gears spin on it. Bearings ride on it. Pulleys rotate around it. You get both clamping and rotating function in one part.
Key dimensions to specify
| Dimension | Why it matters |
|---|---|
| Shoulder diameter | Determines bearing fit and alignment |
| Shoulder length | Sets the spacing between components |
| Thread size | Defines how it mounts to the mating part |
| Overall length | Total from head to thread tip |
Shoulder tolerance matters
The shoulder is ground to a tight diameter tolerance. Standard is h6 or h7. This precision ensures bearings and bushings fit properly. A sloppy shoulder causes misalignment. A tight shoulder causes binding. We hold tolerances so your assembly runs smooth.
Head styles compared
| Head type | Best for |
|---|---|
| Hex socket head | Tight spaces, Allen key access, high torque |
| Hex head | Wrench access, larger sizes, outdoor use |
| Flat head | Countersunk applications, flush surfaces |
| Headless | Both ends need to be flush, no protruding head |
| Phillips head | General assembly, moderate torque |
| Slotted head | Light duty, simple installation |
Material selection guide
| Material | Best for |
|---|---|
| 304 stainless steel | General industrial, moderate corrosion protection |
| 316 stainless steel | Marine, chemical, salt water exposure |
| Alloy steel | High strength, heavy loads, hardened applications |
| Carbon steel | Cost sensitive, light to medium duty |
| Brass | Decorative, non-magnetic, low torque |
| Titanium | Aerospace, weight critical, high strength |
Strength grades
| Grade | Best for |
|---|---|
| Class 8.8 | General purpose, most common |
| Class 10.9 | Higher loads, demanding applications |
| Class 12.9 | Maximum strength, heavy duty |
Typical applications
- Jigs and fixtures – shoulder acts as guide pin
- Bearing shafts – precision rotation surface
- Mold guide pins – alignment and sliding
- Conveyor rollers – spacer and axle
- Cam followers – pivot point
- Linkage assemblies – rotating connection
- Printing machinery – precision positioning
- Food processing equipment – stainless for hygiene
Custom shoulder screws
Need a non-standard shoulder diameter or length? Send us your drawing. We manufacture to your specifications. Custom head types and materials also available. OEM orders accepted.
YH Fastener has been manufacturing precision fasteners since 1998. Our product range includes shoulder screws, self tapping screws, machine screws, and custom fasteners. We are ISO 9001 and ISO 10012 certified. Every batch is inspected for dimensional accuracy and thread quality. We sell factory direct and ship to over 60 countries.
FAQ
What is the difference between a shoulder screw and a shoulder bolt?
Same thing. Different name. Both refer to a fastener with a smooth shoulder and threaded end.
How tight should the shoulder tolerance be?
Standard tolerance is h6 or h7. For high precision applications we can hold tighter. Tell us your requirement.
Can I get a shoulder screw with a flat head?
Yes. Flat head sits flush with the surface. Good for countersunk applications.
What is the maximum shoulder length you can make?
Up to 150mm for standard sizes. Longer available upon request.
Do you make headless shoulder screws?
Yes. The entire screw is shoulder and thread. No head protruding on either end.
What is the best material for marine use?
316 stainless steel. It resists salt water corrosion.
How do I specify a custom shoulder screw?
Send us your drawing or sketch. Include shoulder diameter, shoulder length, thread size, and head type. We will quote accordingly.