304 Stainless Steel Knurled Thumb Screws Ø M3 M4 M5 M6 Hand Grip Knob Bolts New

Measure the total thickness of the material(s) being clamped, then add at least 1× the thread diameter for minimum engagement depth. For example, clamping 8 mm of panel with an M4 screw requires at least 4 mm of thread engagement, so a 12 mm shank is the shortest safe choice. Longer shanks give more adjustment range but may protrude on the far side.

The 13 mm flange (9 mm tall) is designed for compact assemblies where clearance around the fastener is limited — common in electronics enclosures and small jigs. The 16 mm flange (10 mm tall) provides a larger bearing surface and a more comfortable grip, making it better suited to panels that are adjusted frequently or by users wearing gloves.

304 stainless steel offers good resistance to atmospheric corrosion, fresh water, and many mild chemicals. It performs well in most outdoor environments. For marine or coastal environments with prolonged salt-spray exposure, 316 stainless steel is generally recommended instead. These screws are not coated, so the corrosion resistance comes from the alloy itself and will not degrade over time.

These screws use standard ISO metric coarse pitch: M3×0.5, M4×0.7, M5×0.8, and M6×1.0. This matches the most common tapped holes and threaded inserts used in metalworking, 3D printing, and general fabrication. If your application uses fine-pitch threads, please confirm compatibility before ordering.

Yes. These thumb screws work with any material that has a matching metric threaded hole or insert — including aluminium, steel, brass, and engineering plastics such as acetal and nylon. For soft plastics, consider using a threaded brass insert to prevent thread stripping under repeated tightening cycles.

Hand-applied torque varies by user and knurl grip, but typical finger-tightening on a 13–16 mm diameter head produces roughly 0.3–1.0 N·m depending on thread size. This is sufficient for panel retention and light clamping. For applications requiring a specific preload, use a torque wrench with a socket adapter and do not rely solely on hand tightening.

M3×6 mm or M3×8 mm with a 13 mm flange is the most common choice for 3D printer panels (e.g., Voron, RatRig enclosures) where M3 heat-set inserts are standard. For CNC machine covers with M5 or M6 tapped holes, the 16 mm flange variants provide a more secure grip when the panel is removed and replaced frequently during tool changes.