We never really think about drill bits ... until one snaps, or we don't have the size we need, or we have so other need for hole drilling. Then, drill bits become indispensable. In this article we provide more background on drill bits than what we could provide in the 5 minute video shown here. I am always amazed at how much information there is on seemingly in smaller topics like drill bits.
Lets start off with the most common drill bits, and the ones that have been around for 150 years or so, the common twist bit. Pretty much everyone who ones any kind of a drill, battery operated or drill press will have some selection of these. They are good for both wood and metal and even work ok in some plastics. They are typically inexpensive and last fairly well, and if you have a means to sharpen, they will probably last you a lifetime. Typically made from High Speed Steel they hold an edge well unless you really heat them up drilling holes, then they loose their temper and become dull. At this point you can sharpen them but they will not hold that edge long because the temper has been taken away from them.
For the purpose of this article, we will say there are 2 kinds of twist bits, the blue or black ones which are often coated with something to help the bit from rusting and the so called titanium bits, which are coated with titanium nitride, which is essentially a ground ceramic that helps the drill bit retain sharpness on the very tip of the bit. Otherwise the titanium has very little effect.
Twist bits are perfect for metal, provided you give the bit a staring point with a center punch, and they are ok for wood, not great ... only ok. The problem with twist bits in wood, they can make a bit of a mes of the hole if they are not sharp and they often wander a bit when they first enter the wood which makes for uneven drill holes in some cases. If you try to re-drill another hole too close to an existing hole, invariably the second hole will slide into the first, making an even bigger, uneven mess.
The second bit for this article is a true woodworking bit, normally called the brand point. These are basically modified twist bits, but with very sharp point where the bit enters the wood. The great thing with brad points is they don't wander. When you stick the sharp end of the bit into the wood, that's where the bit will make the hole. Want to make another hole right beside the first hole, no problem with a brad point. Again the tip bites into the wood and stay there.
I have found that brad point bits also make cleaner cuts. The problem with brad points, they are more difficult and or expensive to sharpen and to purchase. A nice compromise is to use twist bits for those holes that are not so critical, then use the brad points for the special hole drilling needs.
The final bit for this section is the forstner bit. In many ways it is similar to brand point bits in that it also has a sharp tip to help prevent the bit from wandering in the wood, but in the forstner bits case, their claim to fame is that they make a flat hole, which is great for mount certain pieces of hardware or other attachments that may need to be done. Forstner bits are most often used in drill presses because they often require more force to drive them into the wood. Unlike twist and brat point bits, the forstners do not help screw themselves into the wood, instead they tend to resist it.
The good news with forstner bits is that if you need to overlap holes, this is probably the best go-to bit for that. The disadvantage with forstner bits, they are difficult and or expensive to have resharpened (and don't hit nails or screws with these bits, that can mean sudden death to the bit).
I am often asked, what bits do I need and what should I get. My answer is ... all three. You probably already have twist bits, best for you to add both brad point AND forstner bits to your suite of drill bits. If you cannont afford kits of several bits of each, do what I do, buy them as you need them. It won't be very long before you have built up a nice collection of brad point and fostner and when it comes to drilling specialty holes, you will be prepared ... and be able to make nice clean holes.
Copyright - Colin Knecht