Best Mortisers

Buying guide for Best mortisers

It’s possible to cut mortises by hand, and, in fact, doing so was once considered a test of a woodworking apprentice’s skill. If you’ve only got a few mortises to cut, then doing so with a chisel and mallet is far and away the cheapest way to do it, too! But if you cut mortises on a regular basis for furniture or construction, a good mortiser soon becomes invaluable.

A mortiser is easy to learn how to use, it can be set up quickly, and a good one produces precise mortises time after time, all day long. You’ll find plenty of choice, too, from lightweight models for the home shop to those for the full-time pro. While they all follow similar principles, there are important differences that you’ll want to consider as you shop.

Here at BestReviews, we’ve been researching all the latest models so we can help you with your decision. Our picks provide an excellent example of the variety on offer, and we look at specifications and features in more detail in the following buying guide.

Precision comes from taking your time and setting up the machine carefully. Remember the woodworker’s adage: Measure twice, cut once.

How a mortiser works

Benchtop mortiser

It’s a basic but efficient design.

• A motor, much like that found on a drill press, drives a chuck or spindle fitted with a hollow mortising chisel. The hollow part houses a drill bit, also called an auger. The four sides of the chisel are sharpened to provide cutting edges.
• As the motor rotates the spindle, a handle plunges the chisel into the wood. The drill bit removes most of the waste, making a circular hole.
• The square sides of the chisel then remove the rest, so with one plunge motion you make a perfectly square hole.
• Guides allow you to move the workpiece horizontally, so you can make further cuts to get a rectangular hole of whatever size you need.

Chain mortiser

This is a portable device used for large pieces of lumber like you find in timber-frame construction. They are too big to fit under a machine, and, in fact, they may not fit inside a woodworking shop! The tool is clamped to the outside of the lumber to be mortised. It still has a plunge action, but instead of a mortising chisel, it uses what is effectively a chainsaw blade. The bottom of the hole is semicircular, but that doesn’t matter.

Door mortiser

The other tool that’s called a mortiser is a door mortiser. It’s a carpenter’s jig designed specifically for cutting lock mortises. Like the chain mortiser, it’s clamped to the door, and a cutter is fitted to a handheld drill.

The base of a benchtop mortiser has holes for a very good reason. Any movement means your mortises won’t be accurate, and if you’re using long pieces of timber, it could be dangerously unstable. Bolt it down!

Features

We’ll assume those who are shopping for chain and door mortisers already know what they’re looking for — both are very function-specific tools — so we’ll concentrate on the shop models, which are much more common and have much greater variety. The things you want to consider as you shop include power, construction, capacities, and clamping.

Power

Horsepower: Motors are rated in either amps or horsepower. While direct comparisons aren’t very accurate unless you know the efficiency of the motor, we can assume that 5 amps (A) equals 1/2 horsepower (hp). It’s the most common size you’ll find on benchtop mortisers. They are 120-volt (V) single-phase mortisers, so you can run one from any standard household outlet.

Professional-grade machines have 3/4- to 1 1/2- horsepower motors, the latter being something of a beast! Despite the increased power, all the machines we looked at still run off 120-volt single-phase. A big motor doesn’t necessarily mean the tool can make mortises more quickly, but it will be able to accept larger chisels (and hence make bigger mortises). It will also handle high workloads.

Speed: The motor’s revolutions per minute (sometimes given as spindle speed) are usually provided, but because these tools rely more on power than speed, it doesn’t make a great deal of difference. Almost all are somewhere between 1,700 and 1,800 revolutions per minute, regardless of size.

Construction

As with all woodworking machines, the more rigid it is, the more repeatable accuracy you’ll have. It should also be more durable.

Cheap mortisers are frequently based on drill presses, with a modest diameter support column, usually made of steel. A rack-and-pinion drive is better than one that’s just clamped. These aren’t bad tools — if you make furniture at home, they can be a great solution — but they do require more attention if you want to maintain accuracy.

Floor-standing models invariably have a steel cabinet as the base, which gives proper support for a heavy machine and provides useful storage, too. These things can weigh several hundred pounds, so it’s a good idea to plan its position carefully, You won’t want to be moving it often!

Heavier-duty models use cast iron, and the columns may be square section with precisely machined dovetail keyways, plus a rack-and-pinion drive for the head. A cast iron base is another advantage, not only providing solid support but also helping dampen any vibration from the motor.

Capacities

Chisels: A standard set of mortising chisels for the home shop usually includes 1/4, 3/8, and 1/2 inch. Many (though not all) of these machines include them. The machine itself may be able to take bigger or smaller chisels even if they aren’t part of the package. Minimum is usually 1/4 inch, maximum is 1 1/2 inches, though the latter would require a large and powerful machine.

Depth: Spindle travel (or head stroke) — in other words, the thickness of material it can take — is also important. Entry-level machines offer around 4 1/2 inches and large mortisers can exceed 9 inches. A depth stop should be fitted and indexed for easier setting. There is also a maximum workpiece width.

Tilt: Several high-end mortisers offer a  tilting head, meaning you can cut angled or even compound mortises (ones that tilt through both X and Y axes).

Clamping

How the workpiece is held and guided varies considerably. On cheap mortisers, there is usually a vertical clamp you adjust so it just touches the top of the work, but otherwise, it’s up to you to hold it in place against the back fence or rig up your own clamps.

Some offer rollers that clamp the opposite side to the fence, so the workpiece can run smoothly left or right as you extend the cut.

The best have tables that can be wound in and out and left or right. The workpiece is clamped firmly in place, and hand wheels guide it with great accuracy. If you’re choosing the latter, you want to check the amount of cross travel (in and out) and longitudinal travel.

Sometimes you want to cut mortises that are thicker (front to back) than the biggest chisel you have. If you have no fence adjustment, as on cheap mortisers, you’ll have to rig up padding by perhaps clamping a piece of accurately dimensioned scrap to the fence.

Better models have a movable fence with a rack-and-pinion guide and quick-release clamps. This gives more precision in setting, resulting in greater accuracy and repeatability. Those that have movable tables controlled by hand wheels are far and away the best for this kind of work. Once the workpiece is fixed, it’s a simple job to move it around and cut any size mortise you like.

Some mortisers store the chisels on the machine. It’s a minor detail, but it’s very convenient. You’ll be amazed how often you lose a chisel in piles of sawdust!

Mortiser prices

Inexpensive

The cheapest bench mortisers are basically a drill press motor adapted to take mortising chisels. They run from $250 to $320. For those with modest demands, one of these offers good value.

Mid-range

Reliable equipment from known brands starts at about $350. Benchtop mortisers of a professional standard with the kind of power for high-output shops cost from $450 to $700.

Expensive

Heavy-duty floor-standing mortisers can cost anywhere from $1,000 to $2,000. Chain mortisers are also high-priced tools, and you can expect to pay upwards of $1,500.

The mortising chisels themselves may not be included in your purchase. Be sure to check, or you could end up with a powerful machine but without the tools you need to start working!

FAQ

Q. Can an ordinary drill press be used as a mortiser?

A. It’s possible, and there are mortising kits that fit many drill presses. It’s worth thinking about as a low-cost alternative, but you need to be careful. We’ve seen a few cheap mortising attachments for drill presses that are very poor quality.

There are a few other things to consider, too. Although a quality attachment will do a perfectly good job, many drill presses don’t have the power of a dedicated mortiser, so productivity may suffer. Also, be sure to check the mortise chisel size and depth capacity. Finally, you want to plan your work carefully. These kits take 20 to 30 minutes to fit or remove, and you can’t use your drill press as a drill while one is attached.

Q. Can I use a router to cut mortises?

A. The simple answer is yes, but it depends on the depth you need. Jigs are available to suit routers, but sizes are limited and they can cost as much as a stand-alone mortiser! Really, it’s about having the right tool for the job. Those we feature can be set up more quickly and will get the work done more quickly, too.

Q. How do I sharpen a mortising chisel?

A. The central drill bit (auger) doesn’t really need sharpening because it’s only roughly removing waste. It’s the chisel edges that need the work. The outsides can be honed by rubbing gently against a flat oil or diamond stone. It’s important to keep them horizontal so you don’t change the shape. The inner edges can be done with a special hand tool for hollow chisels.