Making halving joints

A sturdy halving joint is the cornerstone of a simple joinery project
Halving joints, also called lap joints, are made to fit tightly with strength added by using adhesive and having the shoulders prevent twisting.
The construction consists of two pieces of timber of the same thickness. Where they join, both have half the thickness removed so they fit into each other, creating shoulders to align them. The surface area provides long grain, called Ihc cheek, foi applying adhesive.
Good halving joints arc made with accurate measuring, marking, cutting and assembly. Part four of the Handyman Back to Basics series shows how to use a marking gauge, saw and chisel to create different types of halving joints.

USING A CHISEL
It takes practice to master a chisel and keeping it sharp is the key. PARING is a technique for cleaning up the check of a halving joint, normally using the flat base of the chisel to guide the cut.
Paring is often done in a sweeping motion, keeping the shavings thin to avoid gouging. Pare the waste down to the scribed lines, working from the sides to the centre.
Chiselling with a mallet can give more power and accurate control. TIP If using with the bevel facing down lift the chisel handle for better access.

CHOOSING CHISELS
Chisels are used for carving, cutting, notching and preparing joints. They range from 3mm to 50mm wide with curved, straight or bevelled blade with handles of timber or plastic. FIRMER has a strong, square edge for chopping out joints. BEVEL - EDGE has a bevelled blade for easier cleaning up and working into tight corners. A paring chisel is long and slender for extra control. MORTICE has a thick, tapered blade that can be levered to remove waste when cutting mortice joints.
For lap joints, use bevel - edge chisels. A set of three costs about $35 but if the budget is limited buy a 6mm and 18mm for maximum versatility.
TO PARE BY HAND hold the chisel handle with your stronger hand and direct the blade with the other.
TO USE A MALLET hold the chisel up about 45° and tap the end gently, with the beve. facing up or down.

GLUING END GRAIN
Adhesive doesnt bond well to end grain, which becomes the shoulder, because its unable to grip into the fibres that run lengthways along the timber. Gluing together the long grain areas, called the cheeks, ensures a lot of surface for the adhesive to bond, creating a strong joint.

Types of halving joints

Halving joints are most often cut at 90° although they can be cut at different angles, such as 45° for setting out diagonal bracing. A dovetail joint cut in a trapezoid shape is one of the strongest halving joints.
CORNER HALVING is used at corners as the name suggests. Its quick to cut but should be screwed or pegged to reduce the risk of it failing.
CROSS HALVING is strong and can be cut to fit tightly - The shoulders prevent twisting but there is little margin for error when cutting.
T HALVING has one piece ending in the housing, making it an end lap for one part and a cross joinl for the other.
SCARF HALVING makes a continuous leng:h from two pieces joined end to end, with the shoulders resisting lateral tension.
DOVETAIL HALVING is a variant of the T joint, with the parts cut into a dovetail shape. It can only be separated in one direction due to the wedging effect, making it one of the strongest types of halving joint. Astcpped dovetail joint hides the end grain.

MARKUP THE JOINT
The quickest, most accurate way to mark up a halving joint is to position one piece over the other to mark the outside of the joint and where the shoulders are to be cut on the inside.
CUT THE PIECES using a handsaw, leaving them slightly overlength to allow a margin for error.

MARK UP THE SHOULDER by using one piece as a template for the width and scoring with a u:ility knife.
MARKAROUNDTHE BOARD using a utility knife with a combination or try square then mark with a pencil.

A try square is used to mark lines or check frames for square. The stock, traditionally made from timber, is positioned against an edge with the blade extending at 90° to mark an accurate line.
Check a try square is set precisely at 90° with this 30 - secondtest.

POSITION THE STOCK of the try square against a true edge then mark a line across the board.
FLIP THE SQUARE OVER to check the blade against the marked tine. An accurate square lines up exactly.

MARK THE DEPTH
A marking gauge is used to mark the depth of a joint on all pieces. The stock is set and the same setting is used for all the markings, with the pin used to score the lines.
To use, hold the gauge against the timber to set the stock about half the thickness away from the pin. Tighten the locking nut to hold it.
Make a light puncture then move the marking gauge to repeat from the other side. Adjust the stock so the pin is exactly halfway between the holes, checking from both sides again.
Clamp the pieces then hold the stock, positioning it against the timber. Break the surface with the pin then push or pull the gauge around the timber to score a line.
MOVE THE PIN to halfway across the timber, make a mark then check from the other side, adjusting the stock so the pin is the same distance from both.
SCORE A LINE across the end grain of the joint with the pin. holding the stock between the thumb and index finger to keep it against the timber.
WORK ALONG THE GRAIN to score a line on both sides of the joint then use a pencil to highlight the lines on both sides for visibility.

CUT THE JOINT
The initial steps are the same for all halving joints. The shoulders are cut with a saw then a chisel is used to remove the waste and clean up the long grain area called the cheek and shoulder for an accurate join.
CUT THE SHOULDERS to the depth mark using a handsaw on the waste side, following the lines squared around the sides and across the top.
TO CUT AN END LAP use a chisel to remove the waste along the grain, working in layers to avoid splitting below the depth mark.
CLEAN THE CHEEK then position the chisel against the shoulder and use the bevelled corner to cut through the shavings and clean the corner.
CUT ACROSS THE GRAIN to remove the waste for a cross lap or T lap joint. Cut the shoulders and clean up the cheeks, working from both sides.
The secret to this magazine rack is accurate cutting of two sides to fit snugly using cross halving joints held with PVA adhesive on all interlocking surfaces.
A cutout at the centre adds a feature and makes the rack lighter.
The 400 x 450mm sides are cut from 1800 x 450 x 18mm laminated pine panel, about $25 from a hardware store. To ensure theyre identical, clamp them together on a workbench and use a jigsaw to cut.

Finishing the rack

After cutting and before assembly use a detail sander with 80 grit abrasive paper to smooth all surfacesand round over the edges except those of the halving joint.
Wipe away the dust, assemble. TIP The detail sander can get into Ihe corners of the cutout.

Mark the cutouts

On the sides mark 100mm wide and 198mm long legs, shading the waste. Mark the notches for the half lap joints 50mm long and 18mm wide then mark Ihe ZOO x SOmni cutout.
Cut out the waste Use a jigsaw to cut out the leg waste then cut the notches, leaving about 2mm waste at the slot end to be removed accurately with a 12mm chisel to make them 60mm deep.
Маке the cutout Use a drill with a 16mm spade bit to make a hole in the centre of the cutout then position a jigsaw in the hole to make the cutout, finishing squarely in each corner.