A countersink bit is just a drill bit that has been designed for making a hole in wood so that the head on the screw that you are using is flush with the wood rather than sitting on top of it. There are two main kinds of countersink bits. One type is a regular drill bit except that it has a tapered countersink sitting on the bit so that the pilot hole is made first. The countersink bit then follows and a hole is made for fitting the screw head. The second type of countersink bit is a tapered countersink that doesn’t have a pilot bit.
A majority of countersink bits are machined out of high carbon steel. There are bits with a pilot bit that have stop collars. They can be used for setting the countersink in a way that allows you to control the bore’s depth. That way if you don’t want to have the plug placed in the hole that is made with the countersink, the head can instead be flush with the wood. These are very easy to use. You can use a good bit to make a lot of cuts before you have to replace it.
Here’s the best way to use the countersink bit:
1. First measure the screws you are planning to sink. This will provide you with the size that your countersink drill bit should be at.
2. Measure the wood and mark the place where your first screw will be going.
3. The pilot hole’s depth can be marked using masking tape as long as the countersink bit doesn’t have a pilot bit. This helps to prevent you drilling a hole that is deeper than you would like it to be. If you’ve got the right size countersink bit, this step won’t be necessary.
4. You can use an electric screwdriver or hand drill to screw in the screw. When you use the bit it makes a beveled indentation. This allows the screw to go down in the bevel. It will keep the head of the screw flush with the wood or a bit lower. When you use a regular drill bit and only make a pilot hole, you need a bit of force to screw the screw a few more turns to it sinks level to the word. It’s not the greatest method in the world, but it works still
5. When the head of the screw is a bit lower than the wood is, you’re able to fill the recess in. You can then use wood filler to scrape it level. If you don’t care about the screw showing, you don’t need to do this step.
The counter sink bit on the left is not the most commonly used one, but it still has its place. It will make the counter sink, and then you have to go behind it and predrill the screw hole itself. It adds an extra step to your drilling, but again, does have its useage at times.
The main thing is getting a screw flush without splitting the wood, as well as making it look clean is always best if done with the counter sink bit.