M3*35/40mm Knurled Thumb Screws Aluminum Alloy DIY Hand Tighten Grip Knob Bolts

These are M3 metric screws with a standard 0.5 mm thread pitch. They are compatible with any M3-threaded hole, insert, standoff, or nut that follows the ISO metric standard.

Choose based on your total material stack-up: panel thickness plus the depth of the threaded receiver. As a rule of thumb, you want at least 3–4 full thread engagements (1.5–2 mm for M3) inside the nut or insert. If your panel is thin and your insert is shallow, 35 mm is usually sufficient; for thicker assemblies or when you need extra clamping length, go with 40 mm.

Aluminum alloy thumb screws are designed for light-duty, hand-tightened applications — panel covers, access doors, enclosure lids, and similar uses where vibration loads are low and frequent removal is expected. They are not intended for high-torque structural joints or applications subject to significant shear or tensile loads. For those, use steel fasteners tightened with a tool.

The anodized coating provides good resistance to light corrosion and surface oxidation in dry indoor environments. For outdoor or high-humidity applications, the aluminum substrate can corrode over time if the anodized layer is scratched or compromised. These screws are best suited for indoor electronics, maker projects, and controlled environments rather than prolonged outdoor exposure.

Yes. M3 brass heat-set inserts are one of the most common pairings for these thumb screws. Ensure the insert is fully seated and the thread engagement depth matches your chosen shaft length. The hand-tighten design is particularly well-suited to 3D-printed enclosures where repeated tool use could strip the insert over time.

Color choice is largely functional or aesthetic. Many builders use a single accent color (e.g., Golden or Royal Blue) to make thumb screws visually distinct from other fasteners, signaling "hand-removable" at a glance. Others color-code by zone — for example, Blue for front panel, Red for rear panel. Black and Silver blend in with most enclosure finishes if a low-profile look is preferred.

The minimum order is 1 piece per variant. Each combination of Thread Dia × Length, Color, and Quantity is a separate variant, so you can add multiple variants to your cart to mix colors or lengths in a single order. Select each combination individually from the variant dropdowns above.