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You’ve probably heard of mortise chisels, but what are they and how do they work? A good mortise chisel should be sharpened to a 35 to 40 degree bevel angle, depending on the type of wood you’re working with. This is because hardwoods place enormous stress on their edges. A shallow or blunt bevel angle will result in edge chipping, excessive fibre crushing, or even tear-out along the mortise edge. A sharp, razor-sharp edge will allow you to increase your bevel angle and create a more efficient mortise.
Lie-Nielsen’s mortise chisels
Lie-Nielsen mortise chisels are not the same as bevel-edged chisels. They are rectangular in shape, with a narrower width than depth. Despite the name, mortising chisels are a powerful tool that you will need to sharpen properly. Here are some helpful tips for sharpening them.
Mortising chisels come in a variety of sizes and are generally used in traditional European wooden woodworking planes. There are sizes as small as 1/10”, which are meant for use in smaller-scale pieces and as component parts of full-sized woodwork. While using a power tool is certainly not essential, every woodworker should at least learn how to create a mortise and tenon frame with hand tools. Focusing on mortise and tenon joints will give you a skill that can be transferred to future projects.
Lie-Nielsen’s honing guides are solid stainless steel with a bronze bearing. They come with a set of removable jaws that can be adjusted to fit any length of mortice chisel. Additional jaws are available separately. These are ideal for mortice chisels, while angled jaws are perfect for skew blades.
Ionut, a longtime member of the LMCA, sharpened a 1/2 inch (12mm) mortise chisel. The set came with a quick-change handle with magnetic chuck and two diamond abrasive cones (600 and 220 grit).
Lie-Nielsen’s chisels are made from A-2 tool steel
Lie-Nielsen’s chisels are made from A-2 Tool Steel, and feature Maine harvested Hornbeam handles. Unlike other chisels, these are socket-style and have a friction fit. They can be seated with a simple rap against a bench or other surface. Some people prefer to use glue, but some find hairspray to be a good middle-ground solution.
Lie-Nielsen’s Mortise Chisels are designed with cabinetry in mind. They are ground with parallel sides and are slightly thicker than wide to help keep their straightness in a cut. They are constructed of A-2 Tool Steel and have Maine Hornbeam handles. These chisels are recommended for light cuts in hard woods.
A-2 tool steel is made of a unique molecular structure. It hardens slowly but consistently, and the resulting carbides form during the process. However, A-2 requires long heat soaks to sharpen properly, so the chisel’s edge will become prone to slipping if the bevel angle is less than 35 degrees.
Lie-Nielsen’s Mortise Chisels are available in a wide variety of sizes, which are generally used for traditional European wooden woodworking planes. One tenth’s inch mortise is used for small pieces or parts of full-sized pieces. In fact, all woodworkers should learn to make their mortise and tenon frame by hand, as this skill will transfer to future builds.
Using a hatchet to sharpen a mortise chisel
Keeping the bevel angle on a mortise chiseling tool between 35 and 40 degrees is essential. This angle depends on the type of wood being worked. For hardwoods, a shallow bevel angle can lead to edge chipping or excessive fibre crushing. A shallow bevel angle also encourages tear-out along the mortise edge. Razor-sharp edges allow you to increase the bevel angle and reduce the chance of chipping.
When using a hatchet to sharpen grained mortise chisels, it is important to hold them in the proper orientation. You can use a bench hook, a vise, or a workbench to hold the chisel. Remember that if you hold it vertically, you are risking a breakage. Always hold the chisel with the bevel facing you. This will ensure the blade is stable when striking the wood with a mallet.
One of the most common mistakes that beginners make is trying to sharpen a mortise chimsel using a bench chisel. In fact, bench chisels can be sharpened more easily than mortise chisels. The blade of the bench chisel should be at least three times as thick and rigid as the mortise chisel. The blade should be sharpened by hand with medium-light taps, as a big whack can quickly dull the edge of the chisel.
The second mistake is using a hatchet to sharpen chisels. Using a hatchet to sharpen a mortise chisel is not recommended. This is not only unsafe, but also causes the chisel to mushroom and break. A mushroomed chisel is likely to break or damage a woodworker’s project.
Removing burrs from a mortise chisel
If you are trying to remove burrs from a mortise-chisel, you have many options. Typically, you can simply file them off. However, removing burrs from a mortise-chisel requires some additional steps. First, you should check the sharpening cone angle. It should match the bevel angle on all sides.
To begin, raise the stone to about a 30 degree angle with the cutting edge. With the chisel positioned at this angle, rub back and forth in a figure-eight pattern across the stone. Repeat the process until you have removed all burrs. After removing the burr, you should wipe the stone with an oilstone. Once it is clean and dry, place the stone in the vice. Then, gently stroke the gouge against it with a rag or piece of cotton wool to prevent rusting.
Using a sharpening stone is another way to remove burrs from a mortise-chisel. Using a fine grit of stone, you should be able to find a small burr on the blade before you even see it. You can also rub a fine abrasive on the chisel before mortising. This will prevent the burr from becoming too large.
To remove burrs from a mortise-chisel, follow the same process that you would for any other tools. A sharp mortising chisel is more likely to cut quickly and easily. It is also worth buying a mortising attachment kit to sharpen your chisel. If you do not have a mortising attachment kit, you can purchase a Mortising Chisel & Bit Set that includes a 1/4″-, 5/16″-, and 1/2″-sized chisels.
Using a narrower chisel
Using a narrower chisels for sharpening a mortise hammer can be a great way to clean out the waste that a primary chimel leaves behind. A primary chisel tends to get jammed along the walls as the mortise becomes deeper. The narrow chisel is also useful for cleaning out parings. It fits into the mortise easily, which makes it a useful tool for cleaning out parings.
While a narrower chimsel isn’t essential for sharpening a mortise hammer, it can help you to work with precision. Sharpened chisels make smaller chips, which makes them easier to plunge into work. Sharp chisels also run cooler, which helps you save on energy.
Before sharpening a mortise hammer, flatten the face of the chisel with a grinder. You can use a flat stone or a steel plate coated with silicon carbon powder. Place the chisel face on the grinding surface, and slowly move the chisel blade over it until it is flat. Avoid grinding too much of the face of a hammer as this may reduce the hollow and make later honing more difficult.
When sharpening a mortise hammer, be sure to set the chisel to reference the bevel square and set it in the correct position. Then, lift and sharpen the hammer until it achieves the desired edge. As long as the bevel square is square, you should be able to finish sharpening a mortise hammer.
If the hammer is not sharp enough, use a narrower chisel. The edge should be half-way through the thickness of the mortise hammer to be removed. Then, you should align the cutting edge with the dark scribe line on the end grain. After that, you should start the second stroke, and you should align the first stroke with the second one. Then, you can watch the chisel closely as it splits the end grain scribe line on the side.
