Precision Components
Ground shoulder screws and locating pins with h9 shank tolerance
Ø1.0 – Ø10 mm · Precision Components Overview
A shoulder screw does two jobs with one part: it clamps a component and it locates it. The unthreaded shoulder is ground to a close diameter and acts as a precision shaft, so a linkage, roller or pulley can pivot on it without a separate bearing pin. In miniature mechanisms this consolidation is valuable — every extra part adds stack height, cost and a tolerance in the assembly chain.
We grind shoulders to h9 as standard, with h7 and h6 available for locating duties. Shank roundness and straightness are held tighter than the diameter tolerance because a shoulder that is round but bent will still bind. Threads are rolled and concentric to the shoulder within 0.03 mm, and the transition under the head is radiused rather than sharp to avoid a stress riser in pivot applications.
Shoulder diameter
Ø1.0 – Ø10 mm
Diameter tolerance
h9 standard, h7 / h6 on request
Roundness
≤ 0.004 mm
Straightness
≤ 0.01 mm per 10 mm
Surface finish
Ra 0.2 – 0.4 µm ground
Thread
M0.8 – M8 rolled, concentric within 0.03 mm
Design intent
Six engineering decisions that separate a micro fastener that works from one that merely fits the drawing.
Ground shoulder diameter held to h9 for a sliding fit, or h7/h6 where the pin must locate a bore without perceptible play.
Shank straightness within 0.01 mm per 10 mm prevents binding in long pivot bores even when the diameter gauge reads good.
A controlled radius under the shoulder spreads bending stress, extending fatigue life in rotating pivot joints.
A fine ground finish reduces wear on the mating bore and gives predictable friction torque in pivot mechanisms.
Multi-diameter pins, headed pins and double-threaded stepped pins are produced to drawing for compact hinge stacks.
SUS420 for wear resistance, SUS303 for machinability, SCM415 for case-hardened pivot pins, titanium for weight-critical linkages.
Technical data
Reference data for design and sourcing. For a specific part, the drawing governs — these tables are the starting point for a joint review.
| Shoulder Ø (mm) | Fit class | Thread | Head Ø (mm) | Max shoulder length | Typical duty |
|---|---|---|---|---|---|
| 1.0 | h9 | M0.8 | 2.0 | 8 | Micro pivot, watch movement |
| 1.5 | h9 | M1.0 | 3.0 | 12 | Finger linkage pivot |
| 2.0 | h9 | M1.4 | 3.5 | 16 | Miniature hinge |
| 2.5 | h9 | M1.6 | 4.5 | 20 | Camera module pivot |
| 3.0 | h9 / h7 | M2.0 | 5.5 | 25 | Robot joint idler |
| 4.0 | h9 / h7 | M2.5 | 7.0 | 30 | Small actuator arm |
| 5.0 | h9 / h7 | M3.0 | 8.5 | 35 | Linear guide roller |
| 6.0 | h9 / h7 | M4.0 | 10.0 | 40 | Pulley axle |
| 8.0 | h9 / h7 | M5.0 | 13.0 | 50 | Dexterous hand joint |
| 10.0 | h9 / h7 | M6.0 | 16.0 | 50 | Robot wrist pivot |
Values are typical for the stated material and finish. Actual performance depends on the mating material, engagement length and assembly torque. Confirm with a sample test before design freeze.
Options
Mix these within one part number family. Where a combination is not manufacturable at your tolerance, we will say so at quotation rather than after the first lot.
Where it is used
Representative positions rather than an exhaustive list. Many of our parts are designed for one specific assembly and never appear in a catalogue.
| Assembly | Typical use |
|---|---|
| Dexterous hand finger joints | Ø3–Ø6 h7 shoulder screws as pivot axles for phalanx linkages |
| Robot wrist assemblies | Ø8–Ø10 shoulder screws locating pulley stacks |
| Notebook hinges | Ø2.5–Ø4 shoulder screws as the hinge pivot |
| Camera aperture mechanisms | Ø1.0–Ø1.5 pins guiding blade pivots |
| Medical instrument linkages | Ø2.0 hardened stainless shoulder pins |
| Precision linear stages | Ø5–Ø6 h6 locating pins for rail alignment |
Quality control
Inspection is not a final gate. It is a set of checks placed where a process can actually drift, with the result recorded against the lot code.
01
Shoulder diameter, air gauge or micrometer, 100%
02
Roundness, roundness tester
03
Straightness, dial indicator on V-block
04
Surface finish, profilometer
05
Concentricity thread to shoulder, vision
06
Hardness, Rockwell or Vickers
07
Thread gauge, GO / NO-GO
08
Coating thickness and corrosion, where applicable
Questions
The questions our engineers answer most often on this product family.
Related products
These families are frequently used in the same assembly, or as an alternative when the joint requirement changes.
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Send a drawing or 3D model with the mating material and finish requirement. We reply with a process route, tolerance review and price — usually within two working days.