Knurled Thumb Screws M3.5x22-40mm Aluminium Alloy Hand Grip Knob Bolts High Type

M3.5 refers to a metric thread with a 3.5 mm nominal diameter. It is a distinct thread size — M3 (3 mm) and M4 (4 mm) fasteners will not thread correctly into an M3.5 tapped hole. Always verify the thread size of your existing hole or nut before ordering.

Measure the total thickness of the material(s) the screw must pass through, then add enough engagement length for the nut or tapped hole — typically 1.5× to 2× the thread diameter (5–7 mm for M3.5). For example, a 3 mm panel with a standard nut would typically suit a 22–26 mm shank. If in doubt, size up by one increment.

These thumb screws are designed for panel retention, enclosure access, and light-duty clamping — not for structural load-bearing joints. Aluminium alloy provides adequate clamping force for covers, side panels, and access doors, but should not be used where high tensile or shear loads are expected. For structural fastening, consider steel equivalents.

Anodising is an electrochemical surface treatment that penetrates the aluminium rather than sitting on top like paint, so it is more durable than a coating. Under normal indoor use with hand-tightening, the colour holds well. Repeated over-tightening with tools or abrasive contact can wear the finish over time.

The anodised finish provides light oxidation resistance suitable for dry indoor environments. For outdoor, marine, or high-humidity applications, stainless steel thumb screws would be a more appropriate choice, as aluminium alloy can corrode under prolonged moisture exposure.

Yes — all 10 anodised colours (Royal Blue, Green, Golden, Dark Red, Black, Silver, Purple, Rose Red, Sky Blue, Orange) are available across all 10 shank lengths (22–40 mm in 2 mm steps), in both 1-piece and 5-piece packs. Select your combination using the variant dropdowns above.

No tools are required for standard installation — the high-profile knurled head is designed for hand-tightening. If you need to torque the screw beyond hand-tight for a specific application, a flat-blade screwdriver can sometimes be used on the knurl edge, but this is not the intended use and may mark the finish.