Knurled Thumb Screws with Steps – Aluminium Alloy Hand Grip Step Bolts M3 M4 M5 M6 M8 M10

Match the thread diameter (M3, M4, M5, M6, M8, or M10) to your existing threaded hole or insert. For length, measure the depth of the threaded hole and add any panel thickness. As a general rule, thread engagement should be at least 1× the thread diameter. For example, an M5 screw in a 10mm (≈3/8") deep hole typically needs a thread length of at least 10mm — select M5*10 or longer. When in doubt, go slightly longer and use a washer to adjust the standoff height.

The 'D' value indicates the handle (knob) outer diameter. D12 = 12mm (≈1/2") diameter, D16 = 16mm (≈5/8"), D20 = 20mm (≈3/4"). A larger handle diameter gives more torque leverage for tool-free tightening — useful for larger thread sizes or higher clamping loads. The number after the handle diameter (e.g., *12 or *20) is the handle height in mm.

These aluminium alloy thumb screws are designed for light-to-medium clamping and adjustment applications — not structural or high-torque fastening. They are generally suitable for panel mounting, jig fixtures, electronics enclosures, and equipment covers. For heavy-load or high-vibration applications, stainless steel thumb screws are typically recommended. Contact us to confirm suitability for your specific use case.

Aluminium alloy has natural corrosion resistance due to its passive oxide layer, and the anodized finish adds further protection. These screws are generally suitable for light outdoor or humid indoor environments. However, they are not rated for marine, salt-spray, or highly corrosive chemical environments. For harsh outdoor use, stainless steel variants are typically preferred.

These screws use standard metric threads (M3 through M10) with standard ISO metric pitch. They are compatible with metric threaded holes, brass heat-set inserts, and standard metric nuts and T-nuts. They are not compatible with UNC or UNF imperial thread systems without an adapter or re-tapping.

Yes — the smaller sizes (M3, M4) are commonly used in electronics enclosures, PCB standoff panels, and instrument covers where tool-free access is needed. Aluminium alloy is non-magnetic and lightweight, making it a practical choice for electronics applications. The silver anodized finish also provides a clean, professional look for visible panel hardware.

The handle height (the second number after 'D' in the variant name) is the length of the knurled grip section. A 12mm handle is more compact and suited for tight spaces or low-profile assemblies. A 20mm handle provides a taller grip for easier finger tightening, especially with larger thread diameters (M6–M10) where more torque is needed.