While it may seem like a simple task to tighten bolts, if you do it wrong, you can strip the bolt -- specifically when you attempt to directly secure it into metal or wood in situations that don't call for a nut. And some bolts require specific pressure applied to tighten them. Attaching these bolts call for the use of a torque wrench, a specific tool that you can adjust to the foot-pounds needed.
Check the bolt to ensure the threads are sound and not dinged or flattened. Clean the threads if necessary with a wire brush. Wipe off any dirt or grime.
Spray the bolt with a lubricant to make it easier to install and tighten.
Thread the bolt into the hole with your fingers. You don't want to start tightening the bolt with a tool, such as a wrench or socket and ratchet, until you are certain that the bolt threads correctly. Cross-threading the bolt prevents a secure hold and ruins its threads.
Attach a socket of the correct size to the bolt head with a ratchet or use an open-end wrench to tighten it in place. Most bolts, with the exception of left bike pedals, tighten in a clockwise or right-hand direction. Just remember the old saying "righty tighty, lefty loosey," as this applies to the vast majority of bolts or screws that require tightening. If the bolt tightens counterclockwise, no amount of turning it to the right will begin threading it.
Snug the bolt firmly in place but do not over-tighten it. Lag bolts don't call for the use of a nut, as the bolt's threads keep it in place.
Nuts and Bolts
Spray the bolt with a product that prevents rust and seizing, or a locking product when you don't want the bolt to back out.
Add the appropriate washer for the application onto the shank of the bolt against its head. Use a flat washer when you need to spread the force from the head over a larger area, or a lock washer when the part components could move, causing bolt tension to reduce or release. Insert the bolt's shank into the hole until it comes out the other side.
Thread the nut onto the bolt with your fingers, and then tighten by hand until the nut is flat against the component's surface.
Hold the nut in place with one wrench while using a second wrench or a socket and ratchet to tighten the bolt. Tighten until it is snug.
Torque Wrench Tightening
Thread the washers and nuts onto the bolt as needed and finger tighten the nut until you need use a tool to continue.
Place the socket and ratchet on the head of the bolt and a wrench on the nut, and continue tightening the bolt until snug.
Adjust the torque wrench to the foot-pounds required. For example, some models have a sleeve at the end of the torque wrench you turn until it's set to the correct foot-pounds.
Snap the correct socket onto the end of the torque wrench. Place the socket attached to the torque wrench over the head of the bolt. Pull the handle of the torque wrench toward you.
Remove the torque wrench and readjust it on the head of the bolt. Repeat tightening and removing the wrench as many times as necessary until you hear the torque wrench make multiple clicking noises. This indicates you've achieved the necessary foot-pounds for your setting.