What's In The Name? Lag Screws and Lag Bolts
Lag bolts or lag screws are bigger screws that are used as a secure fastener for heavy timbers used for big constructions like bridges, railways, beams and posts. Lag screws are very advantageous in a way that they are so easy to use, just like any other type of screw. There are a lot of different lag screw variations - hexagonal lag screws, which as the name implies, have hexagonal heads; zinc plated lag screws, which are zinc plated and can only provide little protection from rust; stainless steel lag screws are better because they are rust free compared to the zinc plated ones; silicone bronze lag screws are designed to resist corrosion; and galvanized lag screws are more used for coastal regions.
When you are using lag bolts, it is important that you determine the size that you need. There are a lot of different sizes of lag screws, the important thing to remember is that it should be able to penetrate the first and up to 1/2 0r 1/3 of the second timber you are fastening together and must be proportionate to the to the diameter of the said timbers.
As mentioned earlier, it is very easy to use a lag bolt. The first thing you will need to do is to of course line up the lumbers you are fastening, using a clamp if needed. The next thing that you need to do is to mark the point of entry of the first timber using a pencil or marker, then you begin the drilling. The hole should be 3/4 of the diameter of the size of the lag screw, and the depth, 1/4 to 1/2 inch of the entire length of the shaft.
The last thing you will need to do is to then insert the lag onto the predrilled hole before the screw. A ratchet can greatly help you accurately tighten the lag screw to ensure that the timbers are securely fastened together. When using a ratchet, you should remember to fit it on to the head of the screw and turn it clockwise until the lag screw head finally reaches the wood. A ratchet serves the same basic function as a wrench. If the lag bolts are a bit loose, then you should remove and replace the nut altogether. You can also add a locking washer on to it, so that it grabs the bolt and holds it firmly.
An important thing to remember is that you should never use a lag screw in concrete or metal, as its purpose is for use on wooden surfaces. There are specialized lag screws that can be use for such, with the addition of a special lag insert. These screws are safe to be directly screwed into a wood, unlike carriage bolts, which need to be inserted into a pre existing hole and cannot be driven unto the surface being fastened. The difference is that carriage bolts have a flat end and that lag bolts have a sharp pointed tip.
"What's In The Name? Lag Screws and Lag Bolts", was submitted 08/5/2010 under category Education , Classifieds.