One of the most common questions we get from frustrated readers is why wood splits when driving in a nail. You have probably experienced this before – the nail is all lined up and you hit it directly with the hammer but the wood splits right down the grain causing a nasty crack in the wood. Luckily there are several ways to reduce the chances of this happening on your next wood project.
The first key to preventing nails from causing wood to split is making sure the wood is not overly dry and brittle. After that make sure you choose the right type of nail for the job and the smallest diameter that will get the job done. Drilling a pilot hole, blunting the nail, and avoiding the edges and grain lines will likely solve the problem. Lastly, you can coat the nail with lubricant to help the nail go in smoothly.
We’ll discuss all of these in more detail below.
How to Stop Nails from Splitting Wood
As we mentioned above, nails may split wood for various reasons. A common reason is that you may drive the nail too close to the edge of a wood piece. If the wood is overly hard or brittle, it may crack when you drive a nail into it. Or, if the nail you use is too heavy, it could crack the wood.
Here are ten helpful tips that can help you to treat your wood better while driving nails into it:
Avoid Nailing in the Same Grain Line
An excellent way to prevent splitting when you have to space your nails close together is to avoid nailing them in the same line of the wood grain. Follow each line of the wood grain, and stagger the nails slightly while hammering them to ensure that no successive two nails share the same grain line.
Blunt Your Nail
The process of “blunting” is a simple but effective procedure that you can carry out on your nails. Place your nail on a hard, flat surface with the point facing up. Tap the sharp end with your hammer. The nail will now enter the wood in a cutting motion rather than acting as a wedge.
You may feel that blunting your nail is tedious and time-consuming. Yes, it is both of those. But to get clean, split-free wood at the end of your project will be worth that extra effort you took with your nails.
Use a Lubricant
Mainly when you use nails on brittle hardwoods like oak and maple, using a bit of lubricant on your nails may prevent splitting. The hardness and brittle nature of the wood create friction on the nail while hammering it in. You can dip the tip of your nails in petroleum jelly to minimize friction.
Avoid Nailing on the Edge
When you drive nails into a board, ensure that you don’t hammer them too near the edge. If you have to hammer nails close to the edge, it’s a good idea to hammer them at a slight angle aimed at the inside of the board.
Use Smaller Diameter Nails
The larger the nail you use, the more chance you have of splitting the wood. Try the smallest diameter possible and then gradually increase the size if you feel that you aren’t getting enough grip. You minimize the chances of wood splitting by using smaller-diameter nails.
Drill Pilot Holes
A pilot hole is a small hole that you drill into wood to guide a screw or nail. It can also create a reference point for introducing more significant drill bits to make a larger hole. But when you drill a pilot hole to accommodate a nail (or screw), the hole should be considerably thinner than the nail.
When you drill a pilot hole for a nail, use a drill bit with a diameter slightly less than the diameter of the nail shank. A pilot hole for a screw should be equal to the maximum diameter of the screw (excluding the threads). For screws, you can also get charts that recommend the diameter of the drill bit to use for a pilot hole.
Avoid Brittle Wood
If your wood is extremely dry, it will also be brittle enough to crack easily on impact or with the pressure of a nail being driven through it.
Commercially available moisture meters will indicate when your wood is sufficiently dry to work with or too dry to be brittle. If you have to work with extremely dry wood, do so with the necessary precautions.
Another safe practice to avoid using nails on wood that is too dry and brittle is to use softwood. Softwood comes from evergreen trees like pinewood, Douglas fir, and spruce. These woods are softer and less likely to split when you hammer a nail or drive a screw into them.
Knots are the points in the wood where branches once grew on the tree. When the timber gets sawed at the sawmill, these aberrations get leveled out but form an irregular pattern in the wood grain. The wood in a knot tends to be harder than the surrounding material. If you drive a nail through a wood knot, it might crack.
Be Alert for Cracks
When you are hammering a nail into wood, it is good to keep an eye out for the wood cracking. If you see a tiny crack developing, you can be sure that it will continue and might end up damaging your wood.
If you notice a crack forming, pull out the nail and try to understand the cause of the crack before proceeding further. Using the information we have provided so far, you can probably continue your job but prevent the wood from cracking.
When you watch someone hammering nails into wood, it seems pretty straightforward. However, there is quite a lot of technique and theory behind hammering nails into wood. If you don’t direct your hammer correctly, you may bend your nails and fail to drive them in completely. A great deal of stress and strain is involved in this process.
Your wood can crack suddenly, apparently for no reason. But there are many reasons why wood may crack while nailing it.
Now that we have gone through the various possible causes, we can do a lot to prevent nails from splitting wood. We hope that you will find this information useful in your next woodworking project.