Hand tools

Choose by the fasteners on the machine, not by workshop habit. European, Japanese and Chinese equipment is mostly metric, while older American equipment is often inch. A 13 mm wrench on a 1/2 inch (12.7 mm) head fits loosely and rounds the corners.

DIN and ISO standards set dimensions, hardness and minimum test torque, for example DIN 3113/ISO 7738 for combination wrenches, ISO 2725 for sockets and ISO 5744 for pliers. A tool marked with a standard has been tested to a common level, which is easier to compare than a tool that only states a material such as Cr-V.

When working on or near circuits that may still be live, tools must meet IEC 60900 and carry the double triangle symbol with a 1000 V rating. Ordinary plastic grips are for comfort only and have not been voltage tested.

Wipe off grease and hand sweat after each shift, apply a thin film of rust-preventive oil on bare steel, and store tools in a closed drawer. Silica gel packs or VCI anti-rust paper in the drawer lower local humidity. Chrome plating can still pit where it is scratched, so check worn plating areas regularly.

Spread or worn wrench jaws, rounded screwdriver tips, chipped or misaligned plier jaws, and cracked or mushroomed hammer faces are reasons to retire a tool. Worn tools slip, damage fastener heads and injure hands. Inspect on a schedule rather than waiting for a tool to break.

Sets cost less per piece and give a consistent size range, which suits equipping a new maintenance team. Once a base kit exists, buying individual pieces in the sizes used or lost most often avoids stocking rarely used sizes. List the actual fastener sizes on your machines before choosing.