Wooden screws can be a very effective way to join wood. However, you need to be careful while screwing in, so that the wood does not split. If the boards are narrow, the wood is very dry, or if you screw too near to the edges, the displacement of the wooden screw can force the fibers of the wood apart to split it and ruin the woodwork. This is why you need to be very careful while using wooden screws in place of dowels to join wood. This is an important part of wood crafting that you need to look out for, especially for interior woodworks like cabinetmaking and setting wood spindles.
By taking a few precautions, you will be able to make effective screw joints without splitting the wood. For this, you will need to mark the position on the wood where you need to screw and then drill a pilot hole that is smaller in radius than the shank of the screw that you plan to use. Make sure to drill the hole completely through the piece of wood on the top of the joint and partially through the same at the bottom part. While drilling the hole, do not forget to leave enough material at the end of the screw hole for the screw to bite properly.
In addition, do not screw within half an inch of the end, because even if you drill a hole at these places, the head of the screw might force the wood apart. Another important point to note is that you should not sink the head of the wooden screw more than 1/16 inches past the wooden surface, as this can damage the wood. If you wish to sink the head of the screw deeper into the wood, you will need to drill a hole to countersink the screw. For, this you will need to use a drill bit that is a bit larger than the screw head.
It is also better to roll the screw in paraffin wax before driving it through the wood. This will help lubricate the screw and will let it go smoothly into the wood without splitting it. Additionally, as the top board will be experiencing outward stress, you need to spread carpenter’s glue between the boards. The glue will support the screw and can help to increase the life of the woodwork. In addition, it will lessen the chances of wood splitting while screwing the boards together.