Countersunk Lag Bolts

Why countersunk lag bolts ?

It’s a common question asked, why not use flat head lag bolts, why do I need countersunk lag bolts ? If you're wanting to countersink carriage bolt heads as part of a repair or building into a new project, there are a couple of popular ways to start this process. Firstly once you've measured the diameter and depth of where you are needing to work, you are looking at using either Forstner bits or I prefer  a flat bottomed X-type counterbore. Ensure the areas are measured correctly, then using the correct size counterbore you can proceed to make the holes ready for your countersunk lag bolts to be fastened into.  

So why bother countersinking ?

Countersinking enables you to set all the screws to the consistent depth in the wood ( or other material ) without the possible risk of splitting or damaging the wood. What then happens is that the countersink provides a neat, flush circle around the screw head, thus making the finished job much smarter in appearance. Screwing straight into wood making a hole that isn't counter-sunk, damages the wood grain much more than using countersunk lag bolts. Because the countersink offers a cleaner solution, it doesn't do as much damage and therefore doesn't weaken the stability of the wood as much as going straight in with a screw or even flat head lag bolts. If you don't have the time, the effort or both to use a countersink first, then I would urge that you do use lag bolts and nuts on your job. This type of fastening is best for jobs which won't be expected to carry much weight, where there isn't a countersunk hole prepared. Using lag bolts and nuts together, will offer a tiny bit more stability and prevent any additional damage to the wood where the heads are.  

Flat Head Lag Bolts

  There are some types of jobs where flat head lag bolts just won't cut the mustard. Lazy way would be just to keep tightening, until the actual flat head lag bolts are deep into the wood, which might for a novice, working on a very minor project in the shed down the garden, escape close inspection. This is not the way to work though. If this is for a project that is likely to have to take any weight, then the risk of the damage being done to the wood already is quite high. This being the case, means that once the object is fitted in place, this risk increases and could result in the wood splitting. How many times have we been tempted to say or been told; " I'll just tighten it until it is flush, it will be fine "  Only to discover actually it is not fine and the job needs replacing already. Sometimes speed isn't always the best way to save time. The extra 30 minutes you save originally can soon be lost when you need to dismantle your shed or whatever the project is you were working on, because the wood has been found to be splitting from being damaged from the get go. Yes, countersunk lag bolts may cost a little more, yes they will take longer to put in place but they are worth it.    

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