The clamps commonly used in the wood shop are bar clamps, C clamps and hand screws. All of these clamps have screw spindles that tighten the jaws against the stock. The threads and the movable parts of the clamp should be lubricated occasionally with a lightweight oil to make them work freely.
The bar clamp usually has a spring in the movable jaw to hold it in place after it has been adjusted. Sometimes the spring loses its tension and must be replaced. In such a case, the jaw must be removed so a new spring can be installed. It can be removed by taking out the rivet at the end of the bar. After the new spring has been inserted and the jaw mounted on the bar, replace the rivet to keep the jaw from coming off.
To remove any glue that may adhere to the surface, clean the wooden jaws of hand screws frequently. Glue on the clamping surface may make indentations on the surface of the stock when it is clamped. Apply a coat of boiled linseed oil to the jaws after they have been cleaned. Linseed oil prevents the penetration of glue into the clamp jaws. Do not use lubricating oil because it will not dry and will soak into the stock that is clamped, causing a discoloration.
Occasionally, it is necessary to replace a jaw on a hand screw. The hand screw can be disassembled by driving the pin out of the handles and unscrewing them. The spindles will then screw out of the jaws. In assembling the hand screw, be careful to start the spindles into the jaws at the proper time so the jaws can be closed and will not come off the spindles when they are opened. If it does not work properly, the hand screw should be taken apart and reassembled.