Forstner drill bits might not be one of the essentials for most woodworkers but if you’re looking into doing advanced workings and joinery they should definitely be a consideration. These sometimes fragile, often misunderstood bits allow you to drill a flat bottomed hole quickly and easily and the cost is high, but if you’re trying to find the best set it can take some work.
We’ve done the groundwork for you, so let’s get to the bits.
Best Overall !
For a novice this is a high quality set which will last for some time, you’ll just have to make sure you keep up on the maintenance.
|Grizzly H7694 Master Forstner Bit||31||Serrated|
|Freud 16 Pcs. Precision Shear Serrated||16||Wavy|
Using Forstner Bits
Using Forstner drill bits is a trying process, the kind of thing which leaves even seasoned woodworkers with a bit of a sense of awe. There are other bits that do comparable things, however few of them will work as precisely as a Forstner.
Essentially, they drill a flat bottomed hole with their distinctive design but their design is such that they can also be ruined quite quickly by an amateur. Let’s compare them to a couple of different tools which can be used for comparable purposes.
Forstner vs. Spade
Spades do much the same thing as a Forstner, creating a hole with a flat bottom except for the leading edge of the brad. The brad is the pointy thing at the end of the bit. While they can be used for similar purposes there’s a pretty clear difference in the quality of the hole.
A spade is much quicker, rougher, and more aggressive while a Forstner is a much more precise tool. Think of it like comparing a sawzall to a table saw. The latter can do the same job, but the table saw will do it in a much more precise, controlled, and clean manner.
Forstner vs. Hole Saw
Hole saws are generally much faster, if you’re running conduit through a 2×4 in framing or something they’re probably the better choice. They’re also easier to use with a hand held drill since they don’t need such a low speed.
On the other hand Forstner bits deliver a clean hole with a greatly reduced chance of tear out or other “mess” that a hole saw leaves behind. They’re worth the price for any kind of specialized holes you need.
So, When Do I Use a Forstner?
You’ll want to use a Forstner bit when precision and cleanliness of the cut outweighs the need for expediency. For dowel joinery there’s simply no better tool, but there is one fairly major caveat:
Forstner bits are not meant to be used with a hand held drill, instead you need a drill press with a precise speed control. If you get things going too fast you can damage the bit, sometimes irreparably.
You can use them with a steady hand and a normal drill, but it’ll be hard on the bit, your workpiece, and the drill since most of them aren’t meant to be used at low speeds. The bits also have a tendency to “skitter”, or move around the surface of the workpiece. Only use them with a hand held drill if you absolutely have to.
In all cases when you use one you need to make sure they don’t get too hot. If the bit is blued, then you just messed things up and you’re going to be looking into buying a new one and that can get pricey in a hurry.
What to Look For in a Forstner Bit
There’s really only a few things to look at with these tools. Most people who are manufacturing them know what they’re doing, these aren’t bits which are usually churned out in cheap metals meant for light DIY use since they’re so specialized.
You’ll want to know which sizes you’re planning on using. These bits can cost a lot and if you’re looking to maximize the amount of work you’ll be able to get out of them then there’s a good chance that you already have a project in mind.
While you can purchase them singly for an individual project most people will want to buy a set of them to save money and time when a future job inevitably calls for a different sizing.
Any Forstner bit worth its price will come in one of two different high grade steels. The metal is really most of the cost of the bit, once you get past the advanced machining process.
High speed steel(HSS) is the cheaper material. It will stand up to a bit more punishment than many tool steels and should be considered the bare minimum “acceptable” steel for a Forstner bit to be made out of. It’ll also cost a good bit less than the other acceptable material.
Carbide based steels are superior in their ability to hold an edge and in durability. They also cost a lot more, but if you want a super long lasting bit these are the ones to go with.
Forstners come with a few types of edging which can make a big difference in how you end up using them.
Knife edge bits cut the fastest but are prone to overheating. They have a single raised knife edge and an interruption on the rim. They’re mostly made for bits which are 1” or smaller, since the surface area will result in less friction and a smaller chance of overheating.
Wavy edges have small serrations and a little better heat dissipation. They don’t cut quite as quickly but the way the edge is made has less constant contact with the edges. They also don’t make holes as cleanly at angles, so keep that in mind.
Sawtooth bits can handle higher speeds but have some serious disadvantages. Simply put, they don’t function very well at angles and will induce a bunch of tearout. If you’re going into the wood at 90° however they’re almost ideal.
Which bit is the most advantageous for your project mostly depends on what you plan on doing and your budget. If you’re doing big pieces of joinery then wavy or sawtooth bits made of carbide steel are your best bet, but for smaller, precise projects a knife edge made of HSS should be sufficient. Don’t cheap out on your Forstners and they’ll treat you well.