Thumbscrew with Integral Wrench

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A major drawback with available thumbscrew type products is that sometimes not enough torque can be applied without a separate tool to clamp parts or engage a lock feature which is usually a requirement. The integral wrench greatly increases the torque applied to the screw. All versions include an integral wrench locking feature.

The prototype screws depicted on this page and in the video at are based upon a popular size thumbscrew with a 3/8 threaded shank, 7/8 diameter x 11/16 high head. This screw is commonly used to fasten drawers, containing electronic components etc, to their cabinets for industrial and military applications.

Version #1 depicts the basic screw with a slotted head to stow the integral folded wrench.

Version #2 depicts a screw similar to version #1, but the folded wrench is extendable. The wrench assembly partially pulls out of the hollow shank screw to clear components near the screw. The extension shaft is permanently fastened to the folded wrench and slideably attached to the screw. When the wrench assembly is pulled outwards and rotated, it drives the screw via an external hex area at the end of the extension that engages an internal hex area of the screw just under the head. The internal hex is formed from the threaded end of the screw, but stops slightly below the bottom of the slot in the head so the wrench cannot be removed. The bore in the screw, below the internal hex, is a clearance diameter for the hex portion of the shaft. The points of the hex prevent the wrench from passing through the clearance hole between the bottom of the screw head slot and the end of the internal hex. This allows free rotation of the wrench for orientation and stowing within the screw head slot. This screw can be operated like version 1 or in extended mode.

Version #3 depicts a screw with a spring actuated telescopic wrench. The wrench is stowed within the screw head and deployed when the outer cap is rotated 90 degrees. This wrench has a detent type locking feature.

Some advantages of this device: The ability to apply more torque without a separate tool, maintain a smooth profile to prevent clothing, jewelry or wiring from getting entangled while reducing the number of tools required. This product has some unique characteristics for military, aerospace, industrial, medical, sports equipment and other applications where toolless instant access can be vital.

The product is easily manufactured. Parts can be machined, deep drawn or metal injection molded and easily scaled. Screw heads could be standardized and various shank lengths could be inertia welded to the heads.



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