1. INDUSTRIAL TECHNOLOGY-TIMBER
ASSOCIATED THEORY
TOPIC 3
JOINTS
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2. INDEX FRAMING JOINTS INTRODUCTION THE ROLE OF ADHESIVES
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FRAMING JOINTS
INTRODUCTION
THE ROLE OF ADHESIVES
MORTISE & TENON JOINTS
CARCASE JOINTS
WIDENING JOINTS
DOVETAIL JOINTS
BISCUIT JOINTS
HOUSING JOINTS
KNOCK DOWN FITTINGS

3. INDEX
JOINTS
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.

4. JOINTS INDEX THE ROLE OF ADHESIVES
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.
strength
ease of application

5. JOINTS INDEX THE ROLE OF ADHESIVES
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.
surface area
appearance,
strength,

6. JOINTS INDEX CARCASE JOINTS box
Carcass joints are associated with ……….. like
constructions and have members joining usually at
……………… angles. The two types of carcass joints
are ……………. and …………………..carcass joints.
right
corner
divisional
The following slides illustrate the most common joints and their typical applications

7. JOINTS INDEX CARCASE JOINTS Can be strengthened with nails or screws
Butt Joint

8. JOINTS INDEX CARCASE JOINTS Can be strengthened with nails or screws
Butt Joint
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9. JOINTS INDEX CARCASE JOINTS
Butt joints in framing may also be strengthened by fixing a nail plate or corrugated fastener over the outside, or a timber block may be fixed to the inside.

10. JOINTS INDEX CARCASE JOINTS Rebate & butt joint
Increased surface area for gluing
Reduced end grain showing
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11. JOINTS INDEX CARCASE JOINTS
This may also be known as the “rabbit” joint

12. JOINTS INDEX CARCASE JOINTS Mitre Joint
Can be strengthened by nails, or screws or……

13. JOINTS INDEX CARCASE JOINTS
A spline may be added to strengthen the joint.
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14. JOINTS INDEX CARCASE JOINTS
Mitre Joints are typically used in picture framing

15. JOINTS INDEX CARCASE JOINTS
Dowel Joint. It is another way to strengthen the simple butt joint.
The pins, or dowels should be approx 1/3 of the thickness of the timber
The number of pins depends on the width of the timber.

16. CARCASE JOINTS-Dovetail Joints
INDEX
JOINTS
CARCASE JOINTS-Dovetail Joints
These 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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17. INDEX
JOINTS
Dovetail jigs are often used with a router.

18. CARCASE JOINTS-Dovetail Joints
INDEX
JOINTS
CARCASE JOINTS-Dovetail Joints
Single Dovetail.

19. CARCASE JOINTS-Dovetail Joints
INDEX
JOINTS
CARCASE JOINTS-Dovetail Joints
Common or through dovetail joint.

20. CARCASE JOINTS-Dovetail Joints
INDEX
JOINTS
CARCASE JOINTS-Dovetail Joints
Lapped dovetail joint.
Advantage over through dovetail
End grain only shows from one direction

21. Dovetail joint applications
INDEX
JOINTS
Dovetail joint applications

22. Dovetail joint applications
INDEX
JOINTS
Dovetail joint applications

23. INDEX
JOINTS

24. JOINTS INDEX Housing Joints Through housing
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

25. JOINTS INDEX Housing Joints Stopped housing Advantage:-
The joint cannot be seen when it has been assembled.

26. JOINTS INDEX Housing Joints
The stopped housing joint is typically used in bookcase construction, and can be strengthened with dowels or screws.
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27. JOINTS INDEX Housing Joints
A dovetail housing joint is very strong, but may be difficult to construct.

28. INDEX
JOINTS
Framing Joints
Tee Halving Joint

29. INDEX
JOINTS
Framing Joints
Cross Halving Joint

30. JOINTS INDEX Framing Joints
This joint may be strengthened with dowels….
Corner Halving Joint
or screws.

31. JOINTS INDEX Framing 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

32. INDEX
JOINTS
The unsightly end grain is not seen with a mitre joint

33. JOINTS INDEX Mortise & 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.

34. INDEX
JOINTS
Mortise & Tenon Joints

35. JOINTS INDEX Mortise & Tenon Joints
Joint can be constructed on any angle

36. JOINTS INDEX Mortise & 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 & Tenon

37. JOINTS INDEX Mortise & Tenon Joints
A Haunched Mortise & 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: After assembly the joint is invisible from the end.

38. JOINTS INDEX Widening Joints
Widening joints are used to make slabs of solid timber that are wider than is normally available.
The most common widening joint is the simple butt joint.
It can be strengthened by using dowels or biscuits.

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

40. INDEX
JOINTS
Butt joint

41. INDEX
JOINTS
dowel joint

42. INDEX
JOINTS
Tongue & groove joint is common in flooring, but may also be used as a widening joint

43. These are some variations of the tongue & groove joint
INDEX
JOINTS
These are some variations of the tongue & groove joint

44. INDEX
JOINTS
Biscuit joint

45. INDEX
JOINTS
Biscuit joints can be used as carcase joints as well and are popular because they are easy to construct with a biscuit joining machine.
Construction Steps
The slot is cut on each member with the machine.
The biscuit is inserted with glue.
The joint is clamped together.

46. JOINTS INDEX Knock Down Fittings
These 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.

47. JOINTS INDEX Knock Down Fittings
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……..

48. INDEX
JOINTS
Cam lock or Pin and cam assembly.

49. INDEX
JOINTS
Threaded insert
Connecting block

50. INDEX
JOINTS
Cross dowels, used in chair construction

51. INDEX
JOINTS
Connector bolt.

52. INDEX
JOINTS
Shelf Support.

53. INDEX
JOINTS
Pin and cam assembly with plastic cap

54. INDEX
JOINTS
The end of Topic 3