Torx Driver Bit Size and Tool Matching Guide

Torx Driver Bit Size and Tool Matching Guide

Hexalobular screws require matching Torx bits to realize their anti-cam-out advantage. Wrong bit selection causes poor engagement, premature bit wear and even screw head damage. This guide introduces T-series sizes and matching points.

T-Series Size Reference

Common bit sizes include T6, T8, T10, T15, T20, T25, T30 and T40. Generally, larger screw diameters require larger bits. For example, M3-M4 commonly uses T20, M4-M5 uses T25, and M5-M6 uses T30, depending on head style and recess design.

Bit and Tool Selection

For automated assembly, choose high-hardness S2 bits and inspect wear regularly. For high-torque stations, use magnetic or locking bits to prevent detachment at high speed. For precision torque stations, use digital torque wrenches or servo spindles.

Avoiding Common Problems

Never use worn bits for forced tightening to avoid damaging the recess. Tamper-resistant star screws require corresponding hollow bits. Never use mismatched bits as a workaround.

Torxscrew provides bit selection advice for standard and tamper-resistant star screws.