M3.5 Knurled Thumb Screws Aluminum + 304 Stainless Steel Hand Grip Knob Bolts

The aluminum alloy version is lighter, making it suitable for weight-sensitive applications such as RC vehicles, portable enclosures, and 3D printer frames. The 304 stainless steel version offers significantly higher corrosion resistance and tensile strength, making it the better choice for outdoor fixtures, humid environments, or assemblies that require higher clamping force. Both share the same M3.5 thread and knurled head geometry.

No. These are M3.5 metric thread screws with a 0.6 mm pitch. M3.5 is a distinct thread size and is not interchangeable with M3 (smaller) or M4 (larger). Before ordering, confirm your tapped hole, insert, or nut is specifically sized for M3.5. Using the wrong thread size risks cross-threading and damage to both the fastener and the mating part.

Measure the total thickness of the material(s) being clamped, then add the engagement depth required in the mating thread (typically 1.5× to 2× the thread diameter, so approximately 5–7 mm for M3.5). For panel-mount applications with a captured nut, shorter lengths (4–10 mm) are typically sufficient. For through-bolt applications or thicker assemblies, lengths of 12–40 mm provide the necessary reach. When in doubt, select a length slightly longer than calculated — excess thread can be accommodated with a washer or nut.

Knurled thumb screws are designed for hand-tightened, low-to-moderate clamping force applications. The 304 stainless steel variants offer meaningful tensile strength for light structural connections, but neither material variant is rated for high-vibration or high-load structural joints where torque-specified fasteners are required. These are best suited for access panels, adjustment fixtures, electronics enclosures, and similar applications where finger-tight is the intended installation method.

Anodized aluminum finishes are integral to the surface of the material rather than a coating applied on top, which means they resist chipping and peeling better than paint. However, repeated metal-on-metal contact at the knurl surface will cause gradual wear over many installation cycles. The stainless steel variants rely on the natural finish of the steel rather than anodizing. For color-coded identification systems, inspect periodically and replace individual pieces if the finish shows significant wear.

The 304 stainless steel variants are suitable for outdoor and damp environments — 304 stainless resists rust and oxidation under typical outdoor exposure. The aluminum alloy variants with anodized finish also offer reasonable corrosion resistance for light outdoor use, but are not recommended for prolonged submersion or salt-spray environments. For marine or highly corrosive conditions, contact us to confirm suitability before ordering.

Each variant is sold as 1 PCS (one piece). This allows you to order exactly the combination of sizes and colors you need without committing to a fixed pack quantity. To order multiple pieces of the same variant, simply increase the quantity at checkout. To order multiple different sizes or colors, add each variant to your cart separately.