Best square hole mortising drill bits | For drilling quick square holes

Delta 17-924 vs. Powermatic 1791096

The Delta 17-924 and the Powermatic 1791096 are the two best options if you need a premium quality set of square hole drill bits. Both offer excellent bang-for-the-buck, and you really can’t go wrong regardless of which one you choose.

The 17-924 set is the one to go for if versatility is your main priority. The different sizes span a broad range and will let you cut mortises in various widths. 

The Powermatic 1791096 is no slouch, either. Boasting premium quality carbon steel, these are some of the most durable square drill bits for wood. Their ability to make clean cuts is impressive, and I recommend having a pack of these handy when doing a lot of mortise work, and you need to drill square holes in wood quickly. 

Picking out the best square hole drill bits

#1 Best square hole mortising chisel attachment set

The Delta 17-924 kit provides almost everything you need to cut clean and smooth mortises. With the right drill press, these square hole cutters can create pro-looking square holes with minimal effort. 

The kit comes with four chisels and bits in the following sizes: ¼”, ⁵⁄₁₆,” ⅜,” and ½.” These bits are ideal for the Delta 18-900L drill press, but they will work just as well with the 21313 and 21317 drill presses.

You get a smart-looking carrying case for easy storage and transport of your square drill bits for the price. Unless you make furniture full time–in which case you would probably need a dedicated mortising machine–the Delta 17-924 kit is an excellent addition to your toolbox. 

#1 Best value square hole mortising drill bit set

If you’re looking for a lower-priced alternative that doesn’t compromise quality and performance, the ArtisanShow 6pcs, HSS, Mortising chisel bits are for you. These bits are made to work with almost any brand of a mortising machine on the market, and they can turn any drill press into a very capable mortise cutter. 

The ArtisanShow set comes in a variety of diameters, from 6.5 mm to 19 mm. Each bit is made from heat-treated steel for maximum durability and tested to the most rigorous quality control standards.

If you need a fairly cheap but dependable set of drill bits for construction, renovation, and DIY work, the ArtisanShow set is worth looking into. 

The strongest material for square hole drill bits

The best square hole drill bits are made of tough high-grade steel. Some bits are made from cold-forged steel combined with a black oxide finish that prevents corrosion, resulting in longer usable life. 

There are also square hole drill bits for metal that are made of tungsten carbide steel. This material is supposedly three times more durable than carbide steel. 

How do square hole drill bits work?

Square hole drill bits are used with mortising machines and drill presses. They allow you to cut square holes into wood. 

Square hole drill bits consist of an auger-style bit housed in a hollow square with sharp chisel edges. The auger bit first cuts a round hole into the workpiece, and then the chisel edge cuts out the sides of the hole to make it square. 

For information on how to cut circular holes in wood click here.

Tips for handling square hole drill bits

1. Before you begin drilling a square hole, decide how wide you want your square hole or mortise. You should select a drill bit with a diameter equal to the intended width of your desired hole size. 
2. Once you have selected the proper drill bit and mounted it to your drill press or mortising machine, set the depth stop to your desired depth. It’s always a good idea to mark the mortise position on the workpiece with a pencil before you begin drilling.
3. It is important to use the right amount of pressure according to the material you are drilling into. If you don’t press down hard enough, the drill bit won’t bite into the material. It is better to press down just a little bit too hard instead of not pressing down hard enough.

What other tools can cut square holes?

You can also cut square holes into wood using a jigsaw and a router or drill with beveled chisels. To do this, you will need to drill a hole into the inner side of the square you mark off for the hole. You then use a jigsaw tool to cut away at the hole you’ve just drilled to make it square. You can finish off with a sander to smooth out the edges of the hole. 

For information on the best cordless jigsaws see what I have to say here.  

If all you have is a drill and a chisel, you can cut out a square hole with a bit of work. Again, this requires drilling a pilot hole into the workpiece with your cordless drill. Afterward, you can carve out the sides of the hole to make it square. 

You can also use a rasp, although this is considerably more difficult compared to using other tools. Using a rasp also requires that you have access to both sides of the workpiece, which isn’t always feasible. 

How fast can you drill with a square hole drill bit?

Probably the most time-consuming part of using a square hole drill bit is setting it up for the first time. After you get used to doing it, though, you can attach your drill bit to your drill press in only a few minutes.

After you have it set up, drilling a square hole will only take you as much time as drilling any other hole. 

Comparison of square hole mortising drill bits

Conclusion

The Delta 17-924 offers professional quality mortising features at a very reasonable price. It mounts easily on benchtop drill presses and can be dismounted quickly as well. They are an excellent accessory for cutting out square holes in hardwood, as a cheaper alternative to a dedicated mortising machine while still giving you quality results.

Now that you’ve found out the best way to drill a square hole using a square hole drill bit, you might want to check out the best drill bits for drilling circle holes.