Last Updated on 2021-03-23 by Harry Masterton
Overlapping two pieces of wood is a popular form of joinery that connects two pieces of your project. Fastening the face of one component on another is referred to as a lap joint. Removing material from both pieces, so the thickness is no greater than the thickest member when connected, is called a half lap joint and is a step up above the butt joint.
Learning how to make a half lap joint or halving joint provides you with woodworking joints with lots of gluing surfaces. The joint exceeds the mortise and tenon when resisting shear force (the force that pushes the pieces of wood in opposite directions) on the middle or ends of your lumber pieces.
A similar process is used to make a scarf joint but discussing that is for another article.
The half lap joint has been a popular choice among woodworkers for centuries. Traditionalists still use hand tools and glue to make the joinery, while modern wood shops use powered routers and saws to remove the material that creates it.
How To make A Half Lap Joint
You can even add an angle to create a better-looking wood joint on the corners of your projects to create a mitre joint at a right angle for frames.
This is also know as a corner joint. Using a drill jig, dowel and wood glue you can then create a much stronger dowel joint.
How is a Half Lap Joint Made?
The first step in learning how to make a half lap joint is deciding what woodworking method you will use. In this section, we will take a look at how to cut lap joints by hand.
How to cut a half lap joint by hand: Hand saw method
Joint location is a factor when you are learning how to make lap joints by hand. Using a hand saw for cutting in a lap joint on the end of two connecting boards is fast and easy. The layout is how to make a half lap joint work here.
Two cuts are required here. One is a crosscut that forms the joint shoulder, and a rip cut removes a predetermined amount of the joint's face. Learning how to cut lap joints by hand requires a saw that can reach across the entire face.
Clean-up is required when learning how to make a half lap joint that fits together snuggly. Filing is how to make lap joints by hand with no gap between the shoulder seam and faces. Gaps between the lumber make a weaker joint and are the only problem when learning how to cut a half lap joint by hand.
You might want to use a marking gauge and marking knife when laying out your cut lines. A marking gauge works better for cutting along the grain, while the marking knife works when cutting across wood fibers. The grooves serve as a guide for the saw blade and are how to cut a half lap joint by hand without your saw drifting.
If you are wondering how is a half lap joint made away from the ends when using hand saws, you can always make several crosscuts along the face and then use the saw to cut out the material. That will require a lot of filing and sanding to create smooth surfaces that sit flush against each other.
Another method that can save you time is learning how to cut a half lap joint with a saw and chisel.
How to cut a half lap joint with a saw and chisel
The method most woodworkers use when learning how to make a half lap joint with traditional hand tools is the saw and chisel method. It works well on the end of lumber as well as in the middle of your boards.
You start with a crosscut at the shoulder of the joint. Additional crosscuts on the board's face create rows of material that you remove with a chisel and hammer. The key when learning how to cut a half lap joint with a saw and chisel is making sure these crosscuts do not remove wood beyond your desired depth.
Once you remove the wood with a chisel, you can clean up the face with a file, sandpaper, and even a small block plane. That is how to make a half lap joint anywhere on your work piece by hand with minimal effort.
How To Make A Lap Joint On A Router Table
If you are a power tool user and just learning how to make a half lap joint, you might consider using a router. Making a half lap joint with router bits produces a clean shoulder and face. You will have minimal cleanup on half lap jointer router projects, usually just light sanding.
The trick for making a half lap joint with router bits is finding the actual center of your wood. A center gauge is fast, but you can also use a square to draw a 90-degree line across the edge. Mark an X on the board's edge (between the 90-degree line and the end) to determine the center. The half lap joint router depth should be set to this mark, as it shows the true center.
Learning how to make a lap joint on a router table requires that you use the miter gauge. It will hold your workpiece in place as you remove the excess wood. That will create clean shoulders for the joint, providing you with a snug fit.
Once you make a pass across the half lap joint with router bits, you will reposition the piece for another swipe. It should not take long to learn how to make a half lap joint quickly if you take the maximum amount of material off with each pass. The best half lap joint router bits you select will leave a smooth face that requires only a bit of fine sanding.
Learning how to make a lap joint on a router table will make the cleanest joinery in the shortest amount of time. It should be the go-to for how to make a half lap joint in a production setting.
How To Cut A Half Lap Joint With A Mitre Saw Or Circular Saw
Cutting half lap joints with circular saw
Another power tool for how to make a half lap joint easy would be the circular saw. The trick for cutting half lap joints with a circular saw will be the guide that you use. A mobile guide that you can clamp lets you safely make a lap joint with circular saw.
A depth gauge that provides fine-adjustments is another advantage when cutting half lap joints with circular saw. It allows you to avoid cutting grooves deeper than your desired depth, a common mistake when making a lap joint with circular saw.
How to cut a half lap joint with a mitre saw
A half lap joint miter saw cut eliminates the need for a tool guide. You want a miter saw that uses an arm extension so that you can cut through the entire face evenly. If you are learning how to make a half lap joint with power tools, choosing a half lap joint miter saw project is safer since the power tool is secure.
As you learn how to make a half lap joint with your miter saw, you will appreciate the ability to move the work piece instead of the blade. It can be quicker to cut a half lap joint miter saw project than a lap joint circular saw project. That allows you to finish more joinery and get to assembly more quickly.
Close passes are how to make a half lap joint as clean as possible with either circular saw power tool. You will need more clean-up with chisels, files, planes, and sanders than you do when making half lap joints with other power tools.
How To Cut a Half Lap Joint With a Table Saw
Even if you already know how to make a half lap joint with your table saw, testing with scrap wood will allow you to get a snug fit with your workpieces. Use scrap wood with the same dimensions so that you can make similar cuts for test fits.
Begin with your layout, marking the shoulders and depth of all cuts used to make the half lap joint. Mark your test pieces as well. You can set your blade height using the depth mark on your wood; raise the blade to where the teeth contact the depth line.
You will want to use a dado stack, and it is worth pointing out that these are the types of joinery cuts that these blades excel in making. You will use your miter gauge for the crosscuts, so adding a disposable fence will support the back of your workpieces as the dado blade cuts a wide groove.
You should also set-up a step-off board on your fence. You can butt your workpiece against it to line the cut up. The work piece will move away from the board as it nears the saw blade, providing space between it and the fence (preventing binds that will create kickback).
You can make the first cut to establish one side of the wall on all pieces. For the second wall, cut the test pieces and confirm a tight fit. If it is too snug, you can move the fence away (or loose, move it closer). Learning how to make a half lap joint with your table saw is another way to make this joint with little clean-up needed after the cut.
Half Lap Miter Joint
What is a mitred half-lap joint used for?
These types of joints work well for projects that require a mitered corner. Picture frames are a popular woodworking project that uses mitered joints on the corners, and they are a beginner-friendly project to learn how to cut a mitered half lap joint.
Half Lap Joint Image curtsey of Rockler
The mitered surface offers less gluing surface, so these will be weaker than a standard half-lap joint. Woodworkers reinforce these joints with dowels, splines, or metal fasteners.
What is a mitred half-lap joint used for besides picture frames? You can make mitered half-lap joints around the base or top of cabinets or bookshelves. It works well for joinery on tabletop edges.
How to cut a mitered half lap joint
If you are learning how to make a half lap joint with a mitered angle, you need a guide to align the blade. Hand tool users can build a saw guide that keeps the saw blade at the proper cutting angle (miter gauges and presets do this on power tools). You can use a marking knife to make a groove for the saw blade to sit in as you begin to saw.
Establishing the angled shoulder is the only difference when learning how to cut a mitered joint versus a standard design. Removal of waste is similar to previous methods.
Half-Laps Are Not Half-Measures
Many woodworkers, especially beginners, assume that learning how to make a half lap joint is a waste of time. They mistakenly believe it is a weak joint that serves no purpose beyond picture frames. Lap joints are one of the oldest forms of wood joinery still in use for a good reason.
You will be hard-pressed to find a joint this simple to make that has the shearing resistance of a half-lap joint. It can be reinforced with fasteners to add strength against twisting forces. You can angle the joint to give a more appealing mitered look by sacrificing some of the gluing surfaces.
Learning how to make a half lap joint with hand tools or power tools involves many of the same cuts. Router tables and table saws with dado blades provide the cleanest joints, but you can make a half-lap joint with a hand saw, a chisel, and some extra clean-up.
Give the half-lap joint a try if you have never used it, or revisit it to add strength to your next framing project.
As we progress through this series we will be learning how to make a dovetail joint, a rabbet joint, tenon joint, bridle joint, and dado joint. In later articles we will also cover the box joint, finger joint and groove joint.
If you want to learn how to make butt joints and a mitered butt joint click over to our article here and Woodworking Joints and When To Use Them.
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