M8 M10 M12 Thumb Knob Bolt with T-Handle — D75 Clamping Wing Knob Screw

Select the thread size (M8, M10, or M12) to match the threaded hole or insert in your fixture or machine. For screw length, measure the total thickness of the material you need to clamp through, then add at least 10–15mm for thread engagement. For example, if clamping through a 20mm workpiece, an M8x35mm or M8x40mm variant is generally a safe choice.

Quick length reference: 16mm ≈ 5/8" | 20mm ≈ 3/4" | 25mm ≈ 1" | 30mm ≈ 1-3/16" | 35mm ≈ 1-3/8" | 40mm ≈ 1-9/16" | 45mm ≈ 1-3/4" | 50mm ≈ 2" | 60mm ≈ 2-3/8" | 70mm ≈ 2-3/4"

D75 refers to the outer diameter of the round knob handle: 75mm, which is approximately 3 inches. This larger diameter provides good leverage for hand-tightening without tools, making it comfortable to apply firm clamping force even during extended use on woodworking benches or machine setups.

These clamping knob screws are designed for tool-free hand-tightening applications such as woodworking jigs, machine fences, and fixture clamping. The achievable clamping force depends on thread size and hand strength — M12 variants generally allow greater torque than M8. They are not intended for structural load-bearing joints or applications requiring torque-wrench tightening. For high-load applications, confirm suitability with a qualified engineer.

The knob handle is typically made from durable engineering plastic (such as nylon or glass-filled PA), and the threaded bolt insert is generally steel. This combination keeps overall weight low while providing adequate strength for hand-tightening applications. Contact us to confirm the exact material specification for your order.

The plastic knob body is generally resistant to moisture and light chemical exposure. However, the steel bolt insert may be susceptible to surface rust in prolonged wet or outdoor conditions. For outdoor or high-humidity applications, we recommend applying a light coat of anti-corrosion grease to the threaded portion. Contact us to inquire about stainless steel insert options if needed.

Yes. These thumb knob bolts use standard ISO metric coarse-pitch threads (M8, M10, or M12). They are compatible with any standard metric threaded hole, T-nut, insert nut, or hex nut of the matching size available at hardware stores, making them a direct drop-in replacement for conventional hex bolts in hand-adjustment applications.

The Nut variants are matching D75 hand-tightening knob nuts — they have the same 75mm round handle body but function as a nut (internally threaded) rather than a bolt. These are useful when you need to tighten from the opposite side of a standard bolt, or when building a fully hand-adjustable clamping assembly without any tools. Order the bolt and nut variants together for a complete tool-free clamping setup.