Timber processes Flashcards
Butt joint
A butt joint is the simplest method of joining two pieces of timber together. It relies upon an adhesive such as PVA to make the bond. It is only suitable for very lightweight applications such as modelling. A butt joint is very easy to complete – the pieces to be joined are cut square, PVA is applied and then the joint is clamped until dry.
Dowel joint
Dowels are small round pegs made from a hardwood. They come in a range of diameters for timbers of different thicknesses. Some dowels are machined with grooves that allow wood glue to flow up the dowel when it is hammered into place
Mitre joint
Mitre joints are similar to butt joints in that they rely upon simply gluing and clamping the pieces together. The difference is that the ends of the pieces being joined to make a 90-degree corner are each cut to 45 degrees. They are then glued and clamped, often using a mitre jig to keep the corners straight. Mitre joints are used to make picture frames.
Comb joint
A comb joint is a common joint used to make boxes. It is perfect for this application because the two pieces being joined interlock. The combs also create an increased gluing surface area, which makes a very strong joint. Comb joints can be cut relatively easily using a band saw or laser cut, or with more skill using a tenon saw and wood chisel.
Dovetail joint
Dovetail joints are used in making drawers. They are perfect for this application because they have directional strength. Once glued together, they are impossible to pull apart, so they are excellent for joining the front and back of a drawer to the sides. Dovetail joints can be cut by hand using a dovetail saw or, more commonly, machined with a router and jig that requires much less skill.
They both interlock
Mortise and tenon joint
Mortise and tenon joints are used to make heavy-duty frame constructions for furniture or similar applications.
This particular joint involves making a square or rectangular hole – known as a mortise – in one of the parts to be joined. This might be done with a mortise machine or router, or by simply drilling and cutting using a chisel. The second piece of timber is then cut using a tenon saw or band saw to make the tenon. PVA glue is spread into the mortise and the two parts are clamped together.
Mortise is indented and and the tenon gets in
Housing joint
Housing joints are useful for making framework construction, cabinets and shelving. A groove is cut across one piece, and the end of the second piece is inserted into it. This could be glued in position to make the joint permanent, or left unglued so that it can be taken apart or adjusted. This type of joint is structurally strong, and can be made using a tenon saw and chisel or by using a router.
Timber is indented and you put the timber in
Half lap joint
A half lap joint is used to make simple frames or boxes. It is made by cutting a ‘step’ in the end of each piece. The step is simple to make but it has a larger gluing surface area than a butt joint, making it stronger. Half lap joints are easy to mark out and cut with a tenon saw or band saw.
It’s like two steps that are joined together
Knock down fittings
They are used to manufacture flat-pack furniture. This reduces the making time, and makes it much easier to store the products and transport them. For the customer, KD fittings are relatively easy to use with a limited number of simple tools (sometimes supplied with the product). Flat-pack furniture is often available for customers to buy in a store and take it home with them straight away. It is also easier to carry through doorways and upstairs than fully assembled items.
Modesty block
Modesty blocks are small, rigid, polymer blocks. They have moulded holes that take screws which are used to join the block to panels. Typically, this type of block might be used on cupboards and storage units. It is simple to use but it does not make a particularly strong joint and it is unattractive, so is becoming outdated in mainstream furniture manufacture.
Barrel nut and bolt
A common KD fitting is the barrel nut and bolt. This uses a cross dowel that is fitted into one of the pieces to be joined. The bolt is inserted through the other piece of timber and tightened into the cross dowel (often using an allen key).
Barrel nut and bolt fittings are used to assemble parts of flat-pack furniture such as the frame of a bed or table.
Cam-lock connector
Cam-lock connectors consist of a metal dowel that is screwed into one of the pieces by inserting a screwdriver into the slot on the side. The cam is a disk that fits into a pre-drilled hole in the other piece. When the disk is rotated with a screwdriver, the collar on the dowel locks into the cam and pulls both pieces tightly together.
Wood screws
When joining two pieces of wood together, the top part is drilled with a clearance hole that the screw simply pushes through. The bottom piece of timber has a pilot hole (thinner than the thread) so that the coarse pitch of the thread bites into the timber.
Wood screws can have a countersink (conical head). This allows the screw to fit flush with the surface of the wood providing that a countersunk hole is drilled.
Bolts
Bolts that are used to join wood pieces together – called ‘coach bolts’ – have a thread that runs about two-thirds of the way along the bolt. Under the domed head of the bolt is a square piece that digs into the wood when tightened, preventing the bolt from rotating. This means that when the bolt is tightened, the domed head cannot be undone with a spanner. This is useful in fitting bolts or locks to wooden doors because it makes them secure if the domed part is on the outside.
Turning process
Turning involves machining wood on a wood lathe. There are three methods for doing this: turning between centres, turning on a faceplate or turning in a chuck.
Turning involves machining wood on a wood lathe. There are three methods for doing this: turning between centres, turning on a faceplate or turning in a chuck.
Turning on a faceplate is used to machine items such as domes or bowls.
