M5-M10 Thumb Screws Black Plastic Four Star Head Hand Grip Knob Bolts Galvanized

These thumb screws use standard ISO metric coarse thread pitch. For M5 that is typically 0.8 mm pitch, M6 is 1.0 mm, M8 is 1.25 mm, and M10 is 1.5 mm. If your application requires fine pitch, contact us to confirm before ordering.

Measure the total material thickness you need to clamp, then add 2–3 thread diameters of engagement depth into the nut or threaded insert. For example, clamping 10 mm of panel with an M6 nut requires at least 16 mm total shank length. When in doubt, size up — excess thread can be accommodated with a standard hex nut.

The carbon steel shank provides adequate strength for light-to-medium duty panel fastening, equipment covers, and adjustable fixtures. They are not rated for structural load-bearing joints, high-vibration environments, or applications requiring certified fastener grades. For critical structural connections, consult an engineer and use grade-rated fasteners.

The zinc galvanized coating provides corrosion resistance suitable for typical indoor environments and occasional light moisture exposure. For outdoor or high-humidity applications, consider applying a corrosion-inhibiting coating or using stainless steel fasteners instead. The plastic knob head is not affected by surface rust.

Yes. The shank uses standard ISO metric coarse thread, so these thumb screws are compatible with any standard metric hex nut, wing nut, T-nut, or threaded insert of the matching diameter and pitch. No special hardware is required.

Hand torque depends on finger strength and knob diameter, but the four-star grip profile typically allows 0.5–2.0 N·m of hand torque for M5–M8 sizes under normal conditions. For applications requiring precise clamping force, use a torque wrench on the shank flats if accessible, or specify a locking insert to maintain position.

The first number (M5, M6, M8, M10) is the thread diameter — this must match your nut or threaded hole. The second number (8 mm, 20 mm, etc.) is the shank length measured from under the knob head to the tip of the thread. Choose the shank length based on your material thickness plus required thread engagement depth.