UNC Knurled Thumb Screws – Aluminum Alloy Hand Grip Knob Bolts with Through Hole

Match the thread size to your existing tapped hole. This product is available in three sizes:

• 6#-32 UNC — approximately 0.138" (≈3.5mm) diameter; typically used in electronics enclosures, instrument panels, and light-duty fixtures.
• 1/4-20 UNC — approximately 0.25" (≈6.35mm) diameter; the most common general-purpose UNC size, widely used in woodworking jigs, camera equipment, and machine fixtures.
• 3/8-16 UNC — approximately 0.375" (≈9.5mm) diameter; suited for heavier assemblies and larger panel fastening applications.

If you're unsure, measure your tapped hole diameter or check the thread pitch with a thread gauge before ordering.

These thumb screws are made from aluminum alloy, which is generally lightweight, resistant to oxidation, and suitable for repeated hand-tightening cycles. Aluminum alloy is commonly used in applications where weight savings matter — such as portable equipment, drone frames, and optical instruments. For applications requiring higher torque or structural load-bearing, steel thumb screws would typically be a better fit.

Aluminum alloy generally offers good resistance to light moisture and oxidation. The anodized color finish may provide additional surface protection. However, for prolonged exposure to saltwater, chemicals, or extreme weather conditions, we recommend confirming suitability for your specific environment. In most cases, these are well-suited for indoor and sheltered outdoor use.

These knurled thumb screws are designed for light-to-medium clamping and panel-fastening applications where hand-tightening is sufficient. They are not typically intended for high-torque or structural load-bearing use. The 3/8-16 UNC size generally supports higher clamping loads than the 6#-32 due to its larger thread engagement area. For specific load ratings, contact us to confirm.

Yes. All three sizes follow standard Unified National Coarse (UNC) thread specifications and are compatible with any standard UNC tapped hole, hex nut, or coupling nut of the matching size. UNC is the most widely used inch-series thread standard in the United States, so these will fit the vast majority of American-made hardware.

The axial through hole runs through the center of the knob head, allowing a rod, cable, alignment pin, or wire to pass through the fastener body. This feature is particularly useful in:

• Optical rail and camera rig assemblies where a rod must pass through the knob
• Jig and fixture setups requiring a secondary alignment pin
• Cable management applications where a wire needs to route through the fastener

The 10 color options are achieved through an anodizing or surface coating process and are primarily for aesthetic and color-coding purposes. The color finish does not affect thread dimensions or mechanical performance. In most cases, the anodized finish also provides a minor degree of additional surface protection compared to bare aluminum.

Absolutely. Each size and color combination is available in quantities of 1, 5, 10, 50, or 100 pieces. We recommend ordering a single unit first to verify thread fit, knob diameter clearance, and color before placing a larger order for production or stocking purposes.