M5 T-Bolt Square Head Screws — Stainless Steel 304 (A2) for T-Slot Aluminum Extrusion Profiles

A practical rule: select a bolt length equal to the thickness of the material you're clamping plus enough thread engagement for your nut (typically 5–8mm minimum). For example, if you're attaching a 10mm aluminum plate to an extrusion, a 16mm (5/8") or 20mm (25/32") bolt generally works well. For thin angle brackets, 8mm (5/16") or 10mm (3/8") is usually sufficient. When in doubt, go one size longer — you can always add a washer, but you can't add thread length after the fact.

304 stainless steel (A2 grade) per ISO 3506 typically provides a tensile strength of around 500 MPa and a proof load stress of approximately 280 MPa for M5 bolts. This is generally adequate for structural connections in aluminum extrusion frames, CNC machine gantries, and fixture tables under normal operating loads. For safety-critical or high-vibration applications, contact us to confirm mechanical property certifications.

Yes, in most cases. 304 stainless steel resists atmospheric corrosion, moisture, and mild chemical exposure well, making it suitable for covered outdoor structures, greenhouses, and workshop environments. It is not ideal for direct saltwater or marine exposure — for those conditions, 316 stainless (A4) is generally recommended. Since these bolts are uncoated, their corrosion resistance comes entirely from the alloy composition.

M5 T-bolts are most commonly used with 20-series profiles (20×20mm, 20×40mm, 20×60mm) and 30-series profiles (30×30mm, 30×60mm) that feature a 6mm-wide T-slot. Many 40-series profiles also accept M5 hardware depending on the manufacturer's slot geometry. Always check your extrusion profile's datasheet for the slot width and T-nut specification — some European and Asian extrusion standards differ slightly in slot depth and head clearance.

It depends on your assembly method. In the most common configuration, the square head of the T-bolt slides into the T-slot channel (head captured in the slot), and an M5 T-nut or standard hex nut is threaded onto the exposed end to clamp your bracket or plate. The square head prevents the bolt from rotating, so you only need one wrench. Some builders also use these in reverse — threading into a pre-installed T-nut from outside the profile. Either way, no special tools are required beyond a standard hex wrench or socket set.

For a typical desktop 3D printer frame (e.g., CoreXY or Cartesian style), you'll generally need 20–50 M5 T-bolts depending on the design. A small CNC router with a gantry system typically uses 40–80 bolts. Larger workbench or modular fixture table builds can require 100 or more. We offer quantity tiers from 1 to 200 pieces so you can order exactly what your BOM calls for — or add a 10–15% buffer for spares.

These use the standard M5 × 0.8mm metric coarse thread pitch per ISO 68-1 — the universal standard for M5 fasteners worldwide. They are fully compatible with any standard M5 T-nut, roll-in nut, hammer nut, hex nut, or flange nut. No adapters or special hardware are needed. If you're sourcing T-nuts separately, look for M5 T-nuts rated for your extrusion series (e.g., "M5 T-nut for 2020 extrusion").