South Grafton High School

Year 10- General Wood

Core Module 2

Name:

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Timber JointsThe majority of joints in cabinet work are very old, and were designed years ago to perform certain duties. From experience, properties have become standard in order to maintain a maximum of strength with pieces they connect.

Joints used in cabinet work may be classified into three main groups;

a) Widening jointsb) Angle jointsc) Framing joints

Widening jointsThese joints are used to produce wide boards from a number of narrow boards by joining them edge to edge.

Butt Joint; A simple joint where the edges of the timber are held together by glue or fasteners. This process makes a weak joint and thus is not generally used for cabinet work or construction.

Dowelled Joint: Similar to a butt joint, added strength being supplied by the addition of dowels glued and inserted into holes in each edge and the boards cramped up. It is important that holes line up as dowels leave no room for error.

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Tongued and Grooved (Tongue and Groove): A common form of widening joint used in flooring boards. Glue can be added to give extra strength. The use of a router with a tongue and grove router bits ensures that making this joint is much easier.

Router bits used for tongue and groove.

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Biscuit Joint: Biscuits joints are secured with pieces of timber that are in the shape of a biscuit and these pieces of timber help to prevent movement and add strength. Unlike dowel joints, some leeway is allowed.

It requires the use of a biscuit joiner which cuts a slot into the mating parts. Biscuits are generally made of beechwood or white birch. When this timber comes into contact with moisture (glue), the biscuit expands, creating a snug fit and tight joint. Biscuits come in three standard sizes No. 0, No. 10 and No.20. with the biscuit joiner being adjustable to cater for the various sizes.

Splined Joint: The spline serves to reinforce the joint and help keep the two sections aligned with each other. This small enhancement adds considerable strength to whatever joint it's applied to. It is created when a wooden spline is inserted and glued into a slot or groove. The slot can be cut on the table saw or through the use of a router. As the spline can be seen, it is desirable to use a timber that blends in or has a contrast in colour.

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Stopped Splined Joint: Similar to a splined joint, in a stopped spline joint the spline is stopped short of the end of the board on both ends to conceal the spline. A plywood spline can be used in this case without it effecting the appearance of the joint.

Angle JointsAngle joints represent joints generally used in box-like construction. The members are joined end to face or have their faces at right angles and have their edges flush.

Housing joint: Housing joints are used when two pieces meet at right angles on their narrow face. A shallow trench is cut across the grain of the vertical member, the shelf or panel is then glued into a simple straightforward housing and all the loads are transferred to the sides of the unit. Pins can further strengthen the joint. Used for fixing shelves to vertical panels in deep cabinets, bookcases, storage units and boxes, or for drawer fronts and carcase/frame construction. Types of housing joints include; through housing (pictured), stopped housing, tapered housing (dovetail housing) and tapered stopped housing.

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Finger joint: A finger joint or comb joint is a woodworking joint made by cutting a set of complementary rectangular cuts in two pieces of wood, which are then glued. It is stronger than a butt or lap joint, and often contributes to the aesthetics of the piece.

Doweled joint: A dowel joint is a butt joint reinforced with wooden pegs. They are commonly used in joining frames, boxes, cabinets and carcases. Dowel holes must be a perfect 90 degrees to the face of the work or the dowel will twist when it is assembled.

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Dovetail joint: Dovetails are the strongest of all joints. The joint is made up of interlocking wedge-shaped elements called pins and tails that resist the forces applied to the joint. This joint looks attractive and, if well made, the decorative quality can be used to enhance projects. In other projects the joint can be hidden completely. Dovetail joints work best when in tension. For example, the most common application of the dovetail joint is in drawer making as the strength of the joints tails and pins resist the pulling forces applied to the drawer.

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Rebate joint (Rabbet joint): a rebate joint is where a rectangular recess is cut along the edge or across the end of timber and joined to another using screws or nails and glue.

Framing JointsThe members are joined end to edge, with their edges at right angles. They are used in frame-like construction such as panelled doors, tables, chairs, picture frames and window sashes

Halving joint: also known as a half lap joint, half the thickness of the wood is cut from each piece, forming one unit. This gives a flush surface with the pieces locked together for strength. There are many types of half lap joints including; cross halving joint, corner halving joint, tee halving joint and dovetail halving.

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Bridle joint: This grouping of joints is stronger than the halving or housing joints because they have a larger gluing area, which gives similar appearance to the mortise and tenon joint, though in most circumstances would not have the same strength.

Mortise and Tenon Joint: the mortice and tenon joint consists of two basic parts; a mortise (a recess cut into a piece of wood that accepts a tenon) and a tenon (a tongue at the end of a board that fits into a mortise).The mortise and tenon joint has been used in the timber framing industry for over 2000 years with many variations;

Haunched Tenon, Concealed Tenon, Mitred Tenon, Bare Faced Tenon, Through Tenon, Blind-edged Tenon, Tusk Tenon, Open Mortise and Tenon, Stub Tenon.

Mortice and Tenon Joint Tusk (Peg) mortice and tenon joint

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Mitre joint: a corner joint formed between two pieces of material, by cutting bevels of equal angles usually (90o) at the ends of each piece. This is a fairly weak joint however, can be strengthened through the use of dowels, biscuits or a spline.

Miter Spline: The miter spline is great for reinforcing picture frames, mirror frames and even cabinet face frames that utiise mitered corners. Small decorative boxes can use contrasting coloured splines with mitered corners for visual effect, as well as reinforcing the joints.

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QuestionsAnswer the following questions in relation to timber joints.

1. What are the three types of joints used in cabinet work?a) __________________________________________________b) __________________________________________________c) __________________________________________________

2. What are widening joints?

3. Name three types of widening joints.a) ___________________________________________________b) ___________________________________________________c) ___________________________________________________

4. Sketch two different types of widening joints.a)

b)

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5. Write in the missing words from the word bank.

A butt joint is where the edges of the timber are joined together using ________ or fasteners. Another version of the butt joint that is reinforced with dowels is the ___________________. It is important that the dowel holes line up as dowels leave no room for _________.Tongue and _____________ joints are commonly used in ______________. Although it can be made using various methods, the easiest method is through the use of a __________ with appropriate router bits.A common form of widening joint used in the school workshop is a biscuit joint. Through the use of a biscuit _________, slots are cut into ______________ parts. Unlike dowel joints, some leeway is allowed. Splined and stop splined joints are used to _____________ the joint and help keep the two sections ________________. The slot can be cut using a table saw or router.

6. Outline how a biscuit joint works.

7. Explain the difference between a splined joint and a stopped spline joint.

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flooring dowel joint aligned

mating groove glue joiner

router reinforce error

8. Describe what an angle joint is and where it is generally used.

9. List three different ways you can use a housing joint.

10. What are the common uses for dowel joints?

11. Label the parts of a dove tail joint

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12. Where would you be most likely to find framing joints?

13. From the description of a halving joint, suggest why is would be called a halving or half lap joint.

14. Sketch a picture of a bridle joint.

15. Label the components of a mortise and tenon joint

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16. Complete the following table;

Name of joint Description Diagram

Butt

Dowelled

Tongue-groove

Spline Joint

Mortise and Tenon Joint

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