JOINTS

TOPIC 3

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INDUSTRIAL TECHNOLOGY-INDUSTRIAL TECHNOLOGY-TIMBERTIMBER

ASSOCIATED THEORYASSOCIATED THEORY

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INTRODUCTIONINTRODUCTION

THE ROLE OF ADHESIVES

THE ROLE OF ADHESIVES

CARCASE JOINTSCARCASE JOINTS

DOVETAIL JOINTSDOVETAIL JOINTS

HOUSING JOINTSHOUSING JOINTS

FRAMING JOINTSFRAMING JOINTS

MORTISE & TENON JOINTS

MORTISE & TENON JOINTS

WIDENING JOINTS

WIDENING JOINTS

BISCUIT JOINTSBISCUIT JOINTS

KNOCK DOWN FITTINGS

KNOCK DOWN FITTINGS

Click on a topic or press Enter Click on a topic or press Enter to commence.to commence.

In the process of making useful articles from lengths of timber it becomes necessary to join the lengths in a number of ways. This may involve joining timber side by side, at a right angle, or even to meet a curved surface.

Carpenters and woodworkers have always sought ways to achieve this in the most efficient manner without compromising strength or appearance.

Whilst nails and screws can be used to join timber their appearance is often unsightly, and is usually nowhere near the strength of the original material.

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With the advent of modern adhesives, with their

increased ………………………..and

…………………………there is less dependence upon strength from the joint itself. This has led to an increase in simpler joints being used more frequently, or the greater use of machines to produce the joints.

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strength

ease of application

THE ROLE OF ADHESIVESTHE ROLE OF ADHESIVES

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Many joints achieve their strength simply through the

increase in ……………………

However the choice of a joint will always rely on the

balance between ……………,

……………………… & complexity to produce the joint.

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surface area

appearance,

strength,

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Carcass joints are associated with ……….. like

constructions and have members joining usually at

……………… angles. The two types of carcass joints

are ……………. and …………………..carcass joints.

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box

right

corner

CARCASE JOINTSCARCASE JOINTS

divisional

The following slides illustrate the most The following slides illustrate the most common joints and their typical common joints and their typical

applicationsapplications

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CARCASE JOINTSCARCASE JOINTS

Butt JointButt Joint

Can be strengthened with nails or screws

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CARCASE JOINTSCARCASE JOINTS

Butt JointButt Joint

Can be strengthened with nails or screws

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CARCASE JOINTSCARCASE JOINTS

Rebate & Rebate & butt jointbutt joint

Reduced end grain showing

Increased surface area for gluing

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CARCASE JOINTSCARCASE JOINTS

Mitre JointMitre Joint

CanCan be strengthened by nails, or screws or……

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CARCASE JOINTSCARCASE JOINTS

A A splinespline may be added to strengthen the joint.

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CARCASE JOINTSCARCASE JOINTS

Mitre JointsMitre Joints are typically used in picture framing

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CARCASE JOINTSCARCASE JOINTS

Dowel Joint.Dowel Joint. It is another way to strengthen the simple butt joint.

The pinsThe pins, or dowels should be approx 1/3 of the thickness of the timber

The numberThe number of pins depends on the width of the timber.

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CARCASE JOINTS-Dovetail JointsCARCASE JOINTS-Dovetail Joints

These areThese are the strongest of all carcase joints and are used in the manufacture of high quality furniture. They can be time-consuming and difficult to make, but can be manufactured en masse with the use of a special ………………………..jig. dovetailing

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CARCASE JOINTS-Dovetail JointsCARCASE JOINTS-Dovetail Joints

Single Dovetail.Single Dovetail.

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CARCASE JOINTS-Dovetail JointsCARCASE JOINTS-Dovetail Joints

Common or Common or through dovetail through dovetail joint.joint.

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CARCASE JOINTS-Dovetail JointsCARCASE JOINTS-Dovetail Joints

Lapped dovetail Lapped dovetail joint.joint.

End grain only shows from one direction

Advantage Advantage over through over through dovetaildovetail

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Dovetail joint applicationsDovetail joint applications

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Dovetail joint applicationsDovetail joint applications

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Housing JointsHousing Joints

These joints consist of one member fitting into a trench on the face of the second member. The depth of the trench is equal to………Approximately 1/3 the depth of the timber

Through housingThrough housing

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Housing JointsHousing Joints

Stopped housingStopped housing

Advantage:-Advantage:-

The joint cannot be seen when it has been assembled.

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Housing JointsHousing Joints

The stopped housing joint is typically used in bookcase bookcase constructioconstructionn, and can be strengthened with dowels or screws.

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Framing JointsFraming Joints

Tee Halving Tee Halving JointJoint

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Framing JointsFraming Joints

Cross Cross Halving Halving JointJoint

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Framing JointsFraming Joints

Corner Corner HalvingHalving Joint

This joint may be strengthened with dowels….

or screws.

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Framing JointsFraming Joints

Which variation of the halving joint is the

 

strongest?……………………………

 

Why?…………………………………

What is the most accurate method for

marking out joints?……………………………..

the dovetail halving

The tail acts as a wedge

With a marking knife

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The unsightly end grain is not seen with a mitre joint

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Mortise & Tenon JointsMortise & Tenon Joints

These are the strongest framing joints and are used where considerable loads are applied. Typical examples include Tables, chairs, beds

and furniture subject to dynamic loads.

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Mortise & Tenon JointsMortise & Tenon Joints

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Mortise & Tenon JointsMortise & Tenon Joints

Joint can be constructed on any angle

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Mortise & Tenon JointsMortise & Tenon Joints

When the mortise is cut right through the timber and the tenon appears on the other side it is known as a Through Mortise & Through Mortise & TenonTenon

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Mortise & Tenon JointsMortise & Tenon Joints

A Haunched Mortise Haunched Mortise & Tenon & Tenon joint does not pass all the way through the timber, (about 2/3), and may have a shoulder if it is at the corner.Advantage:Advantage: After assembly the joint is invisible from the end.

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Widening JointsWidening Joints

Widening jointsWidening joints are used to make slabs of solid timber that are wider than is normally available.

The mostThe most common widening joint is the simple butt joint.

It canIt can be strengthened by using dowels or biscuits.

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Several boards have been joined edge to edge, or “laminated”, to form this table top.Suggest a suitable joining method.

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Butt joint

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dowel joint

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Tongue & groove jointTongue & groove joint is common in flooring, but may also be used as a

widening joint

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These These are some variations of the tongue & groove joint

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Biscuit jointBiscuit joint

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Biscuit jointsBiscuit joints can be used as carcase joints as well and are popular because they are easy to construct with a biscuit joining machine.

TheThe slot is cut on each member with the machine.

TheThe biscuit is inserted with glue.

TheThe joint is clamped together.

Construction Construction StepsSteps

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Knock Down FittingsKnock Down Fittings

TheseThese specialist pieces of hardware have been developed to enable furniture to be assembled on site or by the consumer after purchase of the item in a compact packaged state. What other advantages are there of knock down fittings?

The project can be disassembled for storage or transport.

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Knock Down FittingsKnock Down Fittings

What What are the disadvantages of Knock down furniture?

Specialist tools may be needed to fit them. Sometimes they look unsightly.The following knockdown fittings are readily available from specialist shops, and the list is growing……..

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Cam lock or Pin and cam assembly.

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Connecting block

Threaded insert

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Cross dowels, used in chair construction

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Connector bolt.

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Shelf Support.

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Pin and cam assembly with plastic cap

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The end of Topic 3The end of Topic 3

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