FF-S-86
Shoulder Screws
Mumbai · India
Why Shoulder Screw Precision Genuinely Matters
A shoulder screw’s whole purpose runs opposite to most other screws we manufacture — instead of the threaded portion doing the mechanical work, the smooth, precision-ground shoulder does. That shoulder acts as a pivot axle for a rotating link, a linear bearing surface for a sliding component, or a precisely sized spacer, while the thread below it exists purely to hold the screw captive in a tapped hole. Get the shoulder diameter or its concentricity to the thread wrong, and the part it’s meant to pivot or slide on will bind, wobble, or wear unevenly — the entire point of the design fails.
That’s why shoulder length and diameter tolerance matter far more here than on a general cap or machine screw — a mechanism designed around a specific shoulder diameter needs that dimension held tightly and consistently across every screw in the batch, since the mating component (a bushing, a link arm, a cam follower) is often machined to match it directly. Substituting an uncontrolled or loosely toleranced shoulder screw defeats the precision the mechanism was actually designed around.
Akbar Fasteners Pvt. Ltd. exports to over 50 countries, and our shoulder screw range is manufactured with precision-ground shoulder diameters and verified concentricity, tested under our ISO 9001:2015 quality system.
Where FF-S-86 Genuinely Applies
Precision Ground Shoulder Diameter
Controlled, verified shoulder diameter designed to act as a genuine bearing or pivot surface.
Verified Shoulder-to-Thread Concentricity
Confirms the shoulder runs true relative to the thread, essential for smooth pivoting or sliding motion.
Unambiguous Federal Specification
Removes ambiguity in government purchase orders needing a defined shoulder screw standard.
Hardened for Wear Resistance
Alloy steel construction with hardening options for shoulder surfaces subject to repeated motion.
Shoulder Screw Design Elements
Precision-Ground Bearing Diameter
The larger, unthreaded cylindrical section that acts as the actual pivot or bearing surface in the mechanism.
Smaller Retaining Thread
A thread diameter deliberately smaller than the shoulder, purely to secure the screw into the tapped mating part.
Internal Hex Drive
Standard drive type for shoulder screws, allowing controlled torque without disturbing the shoulder fit.
Shoulder Screws vs Cap Screws vs Set Screws
Confirming which fastener class the mechanism actually needs avoids specifying a screw that can’t do the intended job. This table is the quick reference we use with buyers before quoting.
| Property | FF-S-86 Shoulder Screw | FF-S-107 Cap Screw | FF-S-92 Set Screw |
|---|---|---|---|
| Primary Function | Pivot / bearing surface | Tensioned clamping joint | Point-driven shaft locking |
| Precision Focus | Shoulder diameter/concentricity | Thread and body tolerance | Point hardness/geometry |
| Head Design | Hex socket head | Socket/hex/fillister/slotted | Headless |
| Typical Use | Link arms, cam followers | Machine part joints | Collars, pulleys on shafts |
FF-S-86 Specification Details
Materials We Manufacture In
- Alloy Steel Heat Treated
- Stainless Steel 304 / 316
- Finish Plain / Black Oxide
- Coating Available on Request
How Shoulder Screws Are Made
- Process Machined & Ground
- Shoulder Finish Precision Ground
- Testing Diameter / Concentricity Verified
- Quality Batch Sampled
Available Dimensions
- Shoulder Diameter 1/8″ – 1″ (Inch Series)
- Metric Equivalent Available to Drawing
- Shoulder Length Custom to Application
- Thread Smaller Retaining Thread
Application Areas
Wherever a precision pivot, bearing surface, or linear guide is the actual mechanical requirement.
Linkage & Pivot Mechanisms
for rotating link arms
Cam Followers & Rollers
for cam follower assemblies
Fixture & Jig Alignment
alignment applications
Robotics & Automation Equipment
guide fastening in automated equipment
Mold & Die Components
and pivot applications
Government & Defense Equipment
precision shoulder screw needs
Precision Instrumentation
in instrument mechanisms
General Precision Mechanisms
federally specified precision projects
Standard Export Documentation
Prepared as standard practice for every FF-S-86 shoulder screw shipment.
Mill Test Certificate (MTC)
Heat number, chemical composition, and mechanical property verification for every lot.
Certificate of Conformance
Confirms the shipment matches the purchase order shoulder/thread specification in full.
Dimensional Inspection Report
Verification of shoulder diameter, length, and concentricity to thread.
Certificate of Origin (COO)
Confirms India as country of manufacture for destination customs purposes.
NABL Accredited Test Reports
Independent mechanical and dimensional testing available on request for critical applications.
Commercial Invoice & Packing List
Itemized value, Incoterm, and detailed carton/weight breakdown for customs clearance.
Internationally Recognised Standards Coverage
Related Fastener Grades & Materials
FF-S-92 Set Screws
Headless, point-driven screws for shaft locking instead of pivot/bearing duty.
View FF-S-92 →FF-S-107 Cap Screws
Headed cap screws for tensioned machine-part clamping joints.
View FF-S-107 →FF-P-386 Straight Pins
Our companion federal specification precision locating pin range.
View FF-P-386 →Fasteners Manufacturer & Exporter to the USA
Our broader capability manufacturing to ASTM/ASME and US federal standards.
View USA Export Guide →Need a Genuine
Precision Pivot or Bearing Screw?
Tell us your shoulder diameter, length, and tolerance requirement — we’ll confirm specification and manufacture to controlled precision with full documentation. Akbar Fasteners Pvt. Ltd. responds within 24 hours.
Sales: +91 724 0000 733 · Support: +91 800 9315 333 · sales@akbarfasteners.in