JSS 3 / Basic 9
SIMPLE WOODWORK PROJECTS
Previous lesson :
The pupils have previous knowledge of
in Basic Science in their previous lesson
Behavoiural Objectives : At the end of the lesson , pupils should be able to
- define common joints
- say the classification: framing, widening, etc.
- list the uses of joints
- complete woodwork projects
- give examples of adhesives and abrasives
Instructional Materials :
- Wall charts
- Related Online Video
- Flash Cards
Methods of Teaching :
- Class Discussion
- Group Discussion
- Asking Questions
- Role Modelling
- Role Delegation
Reference Materials :
- Scheme of Work
- Online Information
- 9 Year Basic Education Curriculum
Topic: SIMPLE WOODWORK PROJECTS
Wood can used to fabricate many items that are used in homes, offices and industries. There are certain operations that must take place in the process of constructing or fabricating items for domestic use. These operations include cutting, joining and finishing.
There are five sections in to be examined here:
- Common joints
- Classification: framing, widening, etc.
- Uses of joints
- Woodwork projects
- Adhesives and abrasives
Section 1: Common Joints
Rebated Butt or Plain Lap Joint
This joint is also called angle-lap joint. The end of one piece is lifted into a rebate worked across the end of another piece. It is an improvement on the butt joint as it provides two nailing faces and more gluing areas.
It is used in the construction of boxes, cheap cabinets, book shelves, cheap drawers, carcasses for veneer work. It is used mainly where the strength of joint is not important.
Halving or Half Lap Joint
- Halving Joint
This name is given to joints, where the pieces of wood to be joined are to be halved in their thickness or width so that the faces of the assembled members are flushed. These members, joined end to edge, usually meet at a slope or right angles. There are several examples of halving joint, e.g. corner, cross, and tee joints. They are frequently used for paneled doors, tables, chairs, pictures, frames, etc.
- Corner Halving Joint
This has other names, e.g. edge lap. In corner halving joint, the end and the edge of the pieces to be joined usually meet to form an angle, often at right angles. It is used for the construction of small cabinet doors, frames for cores of cheap flush doors.
The Halving Joint
This name is given to a joint where the end of one of the pieces of wood to be joined or assembled is fixed or mortised to the middle of the other piece. The joint may be right across the wood or stop halfway. It is used for frames and can be nailed to the stile away from the end.
Tee halving joint
Dovetail Tee Halving Joint
When the parts of a frame have to be made in such a way that they do not pull apart, that is, where outside strain occurs, sometimes the socket is stopped to hide the end of the pin. The joint is sometimes slope on one side only, and is called bare face tee halving joint. (This joint can only be separated in one direction).
Face and Side of wood
Every piece of wood has two faces, sides and ends, the faces are wider than the sides while the ends are at the extremes. Once the face side has been selected a face mark is marked on it, pointing to the face edge.
The bridles are simplified forms of mortise and tenon joints with increased bearing surfaces. The joints are sometimes used in place or mortise and tenon joints where a stronger joint than halving joint is required.
Plain Tee Bridle Joint
This sis used in place of common mortise and tenon joint. It is used principally for bracing rails of skeleton framing, gallows and brackets and so on. Dowels can be used to strengthen the joint. This joint is used between rail and leg runs through a decorative end treatment.
Corner Bridle Joint
This joint is often referred to asopen mortise and tenon joint. It can be used in corners of frame construction work. It is used in place of haunched mortise and tenon. Care must be taken to see that the tenon fits the socket without splitting apart the cheeks of the socket, thus causing loosening of the joint.
Mitre Corner Bridle Joint
It is also called mitred mortise and tenon joint. One or both sides of the groove may be mitred as required. It is used when a stronger joint than mitre half joint is required, e.g. mirror frames for decorative appearance.
Haunched Mortise and Tenon Joint
Haunched mortise and tenon joint is usedon corners of stool, and in the construction of frames, such as paneled doors, cases and some table leg framimg. When the tenon is made, a small portion at the base tenon is left to form a haunch. This fits into the groove called haunchingon the end of the stile. The length of the haunch is usually the thickness of the tenon. The main use of the haunch is to prevent movement of the tenon and to strengthen the joint when shrinkage takes place. Wedge may be used to strengthen the joint.
Bare face Mortise and Tenon Joint
This joint is used when the rail is of thinner materials than the stile of legs of ordinary tables.Thetenon has only one shoulder, which is usually ¼ to ½ the thickness of the rail. It can be haunched or it may be full width. It is necessary to mitre the ends of the tenons if the two rails meet at opposite faces of the leg of a table. The bare face mortise and teneon is commonly used where the leg and rail faces are flushed when assembled.
The dovetail joint is possibly the best joint that you can use to join two pieces of wood together at a right angle. Not only is it a very strong joint, but it also adds to the appeal of the woodworking project. Even better; everyone “knows” that a dovetail joint is hard to do, and so people will be even more impressed with your handiwork!
While creating a traditional dovetail joint is not too difficult, it does take quite a long time; using a router speeds up this process considerably.
The simplest way to create dovetail joints is to use a router and a dovetail template jig. The latter is available from any good home improvement store and can cost as little as $70. It’s well worth the investment if you plan on doing many dovetail joints in the future.
Arrange the three pieces of the drawer or box as shown in the first diagram and mark the inside and outside of each piece. In addition, mark the ends of each piece as it is imperative that when cutting the dovetails the correct two ends are cut at one go.
Clamp the front of the drawer and one side into the dovetail machine as follows: the left side of the drawer should be clamped under the front clamp (pointing upwards towards the template) with the inside of the drawer pointing out; the front of the drawer – again with the inside pointing out -should be clamped under the top clamp so that it butts up against the left drawer.
These two pieces should be staggered slightly, rather than being aligned exactly. The precise measurement will depend upon the particular dovetail machine that you are using, and this distance will be supplied with its manual. However, it should be roughly in the region of 7/16 inch.
Once everything is tightly clamped in place, use the router to cut around the template, following the direction of the arrows in diagram two.
Once this is complete, the end result should look like diagram three. Dovetail A should be matched with slot B and so on.
It is well worth practicing with scrap wood before trying the above procedure on any project as it will take a while to get the exact measurements (such as the depth of the router cut) perfect.
f the joint is too loose, slightly increase the depth of the router cut. If the joint is too tight (remember that you still have to squeeze some glue into the joint), slightly decrease the depth of the cut.
Classification of Joints
Joints used in cabinet work may be classified into three main groups.
- Widening joints
- Angle or box joints
- Framing joints
Widening Joints: This includes butt joints, dowelled joint, tougued joint, tongued and grooved, rebated as well as slot-screwed joint. We have discussed three of these above.
Angle or Box Joints: These are joints generally used for fixing together pieces which have their faces at right angle and edges flushed. Examples are simple butt, rebated butt, tongued or dado joint, dovetailed joints, plain mitred joints, etc.
Framing Joints: Framing joints are those used in frame-like constructions where the members are usually are usually jointed end to edge with their edges at right angles. Examples are halving or or half-lap joints, mortise and tenon joints, bridle joints, dowelled joints.
Maintenance Basic Science and Technology 2nd Term Primary 6 Week 10
SSS 2 (BASIC 11) Technical Drawing FIRST TERM e – LEARNING NOTES
The topic is presented step by step
The class teacher revises the previous topics
He introduces the new topic
The class teacher allows the pupils to give their own examples and he corrects them when the needs arise
The class teacher wraps up or conclude the lesson by giving out short note to summarize the topic that he or she has just taught.
The class teacher also goes round to make sure that the notes are well copied or well written by the pupils.
He or she does the necessary corrections when and where the needs arise.
- State the classification of joints
- List the type of joints