S-91185A823 1/4"-28 x 1/2" Thumb Screws

Key Features & Benefits at a Glance

• Enhanced grip and torque application with the multi-lobe head design, allowing for easy hand-tightening without tools in tight spaces.
• Superior corrosion resistance from 18-8 stainless steel construction, ensuring long-term reliability in humid or demanding industrial environments.
• Lightweight, durable head made of black acetal plastic, reducing overall weight while providing excellent impact resistance and a professional appearance.
• Precise, secure fastening with Class 3A thread fit and fine UNF threading, minimizing the risk of cross-threading and ensuring consistent, vibration-resistant connections.
• Broad temperature compatibility with a head temperature range of 32° to 180°F, suitable for various indoor and controlled environment applications.
• Full threading for maximum adjustability along the entire 1/2" length, offering flexibility in clamping and positioning during assembly.
• Compliance with environmental and safety standards including RoHS 3 and REACH, ensuring safe use in regulated industries and global markets.

Professional Applications & Engineering Value

This 1/4"-28 UNF thumb screw combines the strength of 18-8 stainless steel with the ergonomic advantages of a black acetal plastic multi-lobe head, addressing common challenges in industrial assembly and maintenance. The fine thread and Class 3A thread fit provide exceptional precision, reducing installation time and preventing loosening under vibration—critical in electronics enclosures, machinery panels, and instrumentation. The acetal head resists chemicals and wear, while the right-hand threading ensures intuitive operation. Ideal for applications requiring frequent adjustments, such as in prototyping, aerospace components, and medical devices, this screw delivers reliable performance without compromising on environmental compliance or user safety.

Specification Summary & Compliance

This thumb screw adheres to UNF thread standards with a Class 3A thread fit for high precision and a fine thread spacing. It is fully threaded and measures 1/2" in length with a 1/4"-28 thread size. The product conforms to RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring it is free of hazardous substances and suitable for use in regulated industries worldwide.