M5 M6 Cylinder Head Knurled Thumb Screws Stainless Steel Hand Grip Knob Bolts

M5 screws have a 5 mm thread diameter with a 0.8 mm coarse pitch, while M6 screws have a 6 mm thread diameter with a 1.0 mm coarse pitch. Choose based on the tapped hole or threaded insert already in your part. M5 is common in lighter panels and 3D printer frames; M6 is more typical in heavier enclosures and machine guards.

Knurled thumb screws are designed for panel retention and light clamping — not structural bolting. Hand-applied torque is typically sufficient to secure access covers, instrument panels, and adjustable fixtures that do not experience significant pull-out or shear loads. For high-vibration environments, consider adding a lock washer or thread-locking compound.

303 stainless steel offers good corrosion resistance against moisture and mild chemicals, making these screws suitable for light outdoor use and humid indoor settings. For prolonged salt-spray or marine exposure, 316 stainless steel would be a more appropriate choice.

Select a length that allows the screw to engage at least 1× the thread diameter of full thread depth in your tapped hole (e.g., at least 5 mm of engagement for M5, 6 mm for M6). Account for any panel thickness the screw must pass through before reaching the threaded hole. When in doubt, choose a slightly longer screw and use a washer to take up excess length.

Yes. These screws are machined to ISO metric coarse thread tolerances (6g thread class), which is the standard for general-purpose metric fasteners. They will fit any M5 or M6 tapped hole, threaded insert, T-nut, or hex nut conforming to the same standard.

For a single repair or prototype, 1–2 pcs is sufficient. For a small batch build (e.g., 3–5 enclosures with 2 screws each), 10–20 pcs gives you working stock plus spares. For production runs or stocking a workshop, 50 pcs per size offers the best per-unit value. All packing quantities are available for every size combination.

Yes, with care. In aluminium, ensure the tapped hole has adequate thread engagement depth (at least 1.5× the thread diameter is recommended for aluminium). In plastic, use a threaded insert rather than tapping directly into the plastic to prevent thread stripping under repeated removal and reinstallation.