Develop an understanding of the fundamentals of carpentry as a foundation to working with wood in landscaping, building construction, furniture making, fencing or any other application.
This course is not a substitute for the practical instruction one might obtain over a long apprenticeship, internship or other such experience; but it does provide a balanced and broad understanding of wood work; exploring the broad range of applications; and in doing so, complements and enhances the development of your knowledge about carpentry.
Before the introduction of mechanical sawmills in the eighteenth century, this was quite an onerous task. At this time, some timbers were obtained from splitting logs with wedges. These would mainly have been for laths, pegs, poles - uses where the timber didn't need to be especially straight. Larger timbers such as beams and joists would often have been hand cut using trestles to support them, or cut over a saw pit. It took two men to do this, each holding one end of the saw. One man would stand over the timber and the other stood beneath.
Ways of Cutting Timber
During these early times a log was usually cut in one of three ways:
- Boxed heart - this is where just one large beam of a roughly squared section was cut from the centre of the log.
- Halved - the log would be split or sawn down the centre and two rectangular beams produced. Sometimes the halves would be split again to form four posts.
- Slabbed - this is where a log was sawn through in sections to form planks and thin studs. Also known as through and through cut.
The way in which you saw a log can impact greatly on whether the timber warps or not.
If you cut this timber along the dotted lines, it is likely to shrink and have a final shape that is closer to the full lines.
Shrinkage occurs when timber is dried or seasoned because wood naturally holds water, and this water is lost during these processes. As water is lost, the timber shrinks in both thickness (depth) and width. Timber only shrinks nominally across it length and so this is not an issue.
Timber is seasoned (ie. dried) so that shrinkage takes place before the timber is used in carpentry and joinery. Splits, shakes, warps and twists can be removed or cut out before the timber is used during machine cutting.
When a log is converted to timber it is known as 'green wood' to begin with. As it seasons, the timber loses moisture until it eventually reaches a state of equilibrium with the moisture in the air. This is known as equilibrium moisture content (EMC). This value is higher in humid areas and lower in dryer regions. If timber is used in building construction, for example, it will swell less (due to moisture uptake) or shrink less (due to moisture loss) if it has a similar EMC to the local climate.
The moisture content of a given timber is denoted as a percentage. For most joinery work, timber will have a moisture content of between 10 and 20%. Timber with low moisture content (nearer 10%) is preferred for internal work and furniture since it will be in a relatively dry environment and will be less likely to shrink due to moisture loss. Timber with high moisture content (nearer 20%) is better suited to outdoor projects since it will be less likely to swell.
Moisture content for a timber can be read using a moisture meter which provides an instant reading. Otherwise, a sample of the timber can be weighed, then dried in a oven, and reweighed until the weight remains stable.
Stress Grading of Timber
The stress grade or strength of timber is generally classified according to either visual inspection or machine testing. Visual inspection is used to ascertain things like knots, the position or size of shakes or splits, the closeness of growth rings, the slope of the grain, insect (e.g. borer) damage, any fissures or distortions in the timber, and so on.
Machine testing is used to determine the strength and stiffness of a piece of timber. Bending machines are most commonly used where a load is applied to the timber to bend or deflect it.
Species may be grouped according to grades so that different species can be interchanged which have the same strength. Different countries employ different grading systems. Many systems involve grading hardwoods, softwoods and joints - and these may each be graded as unseasoned and seasoned. Timber may be marked with its denoted grade. In some countries these marks are in different colours to make it easier to identify the grade.
Grading systems allow the user to select a timber which will withstand the load it is intended to bear, or to choose a suitable alternative if the preferred timber is unavailable.
This course helps you understand everything from selecting appropriate timber and handling that timber, through to working with appropriate tools and equipment to create things from that timber; whether structures in the garde3n, buildings, furniture or anything else.
WHY SHOULD YOU STUDY THIS COURSE?
Whatever your situation and skills this course will help you to develop and enhance them to enable you to tackle those special carpentry projects.
Anyone working in landscaping or gardening is bound to be dealing with timber construction, in at least some parts of their job. Whether fencing, garden sheds, pergolas, timber furniture or something else; wood constructions do occur in gardens, and landscape professionals need to understand how they are build and maintained.
You may well build things out of timber yourself. You might not. Either way though; you need to know what you learn in this course if you are to make appropriate decisions about what is put into a garden, and/or how it is used and cared for.
Some students may use the knowledge from this course well beyond the outdoors.
What you learn here will make you more able to repair things inside buildings as well: furniture, building interiors or anything else.
Carpentry skills, like many trades, are not as easy to come by in today's world. If you want a good carpenter to do a job for you; it may be difficult to find one, and even if you can, you may be waiting a long time for them to do the job. If you learn carpentry for yourself, you can save on both time and money; not to mention the self satisfaction that comes from doing a job yourself.