Sri Lanka NVQ L3 Carpenter flashcards
Sri Lanka NVQ L3 Carpenter · Build recall with a focused review session.
35 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Wood dust health effect
- Wood dust is a carcinogen causing nasal and sinus cancer, and can cause asthma and dermatitis. Control it with extraction at the machine plus a suitable mask.
- Circular saw kickback control
- Kickback occurs when the blade binds and throws the work back. Prevent it with a correctly set riving knife, a free-closing guard, and support on both sides of the cut.
- Ladder 4:1 rule
- Set the ladder base one unit out for every four units of height, and extend it about one metre above the landing. This keeps the angle safe at roughly 75 degrees.
- Crosscut versus rip teeth
- Crosscut teeth are bevelled to knife through fibres across the grain. Rip teeth are filed square to chisel along the grain and clear waste faster.
- Checking a try square
- Hold the square against a straightedge, mark a line, then flip the square over and compare. Any gap or divergence shows the square is not true.
- Spirit level reversal test
- Place the level on a surface, note the bubble, then rotate it end-for-end. If the bubble reads differently, the vial is out of adjustment.
- Moisture content formula
- Moisture content equals wet mass minus oven-dry mass, divided by oven-dry mass, times 100. Interior joinery is normally specified at 8 to 12 percent.
- Anisotropic shrinkage
- Timber shrinks most around the growth rings (tangential) and about half as much radially, while length change is negligible. Uneven shrinkage causes cupping and twisting.
- Softwood versus hardwood
- The terms are botanical: softwoods are conifers and hardwoods are broadleaved trees. Hardness varies widely, so the label does not guarantee density.
- WBP plywood glue
- Weather-and-boil-proof adhesive makes plywood suitable for exterior use. Interior grades use less durable glue and delaminate when repeatedly wetted.
- Drawing scale 1:50
- One millimetre on the drawing represents fifty millimetres in reality. Multiply a scaled measurement by fifty to obtain the real dimension in millimetres.
- 3-4-5 right angle
- Measure three units along one line and four along the other; the diagonal must be five units for a true right angle. This follows Pythagoras' theorem.
- Rectangle diagonal check
- A true rectangle has equal diagonals. Measure both diagonals during setting out and adjust the corners until the two readings match.
- Datum definition
- A fixed reference level or line from which all heights and settings are taken. It is recorded on drawings and marked physically on site.
- Formwork lateral pressure
- Fresh concrete exerts roughly hydrostatic pressure of about 24 kilonewtons per cubic metre times pour height. Setting time, pour rate and temperature reduce it.
- Formwork striking time
- Vertical faces can often be struck after one to two days. Soffits and props stay until the concrete reaches the strength specified for that element.
- Formwork release agent
- A coating applied to the form face before concreting to prevent adhesion and protect the form surface. It must not stain or weaken the concrete.
- Roof pitch formula
- Pitch is rise divided by run, usually expressed as an angle or ratio. The angle equals arctan of rise over run; 30 degrees is about 0.577.
- Common rafter length
- The rafter length equals the square root of rise squared plus run squared. Add the eaves overhang and allow for ridge thickness when cutting.
- Birdsmouth seat cut limit
- The notch where a rafter sits on the wall plate must not remove more than one third of the rafter depth, or the rafter is weakened.
- Hip and valley rafters
- Hip rafters run from external corners up to the ridge and form a hip roof. Valley rafters sit in the internal intersection where two roof planes meet.
- Standard internal door size
- A common internal door leaf in Sri Lanka and the UK is 762 by 1981 millimetres, or 838 by 1981 millimetres. External doors are usually wider.
- Door leaf clearance
- Allow about three millimetres at each side and top of the leaf. Internal doors need roughly eight to ten millimetres at the floor for clearance and ventilation.
- Fire door swing rule
- Fire doors must swing in the direction of escape and be self-closing. They must be fitted with the tested ironmongery and seals for the rated assembly.
- Mortise and tenon joint
- A projecting tenon on one member fits a mortise cut in the other. It is a strong frame joint used for doors, windows and furniture.
- Floorboard expansion gap
- Leave about one to two millimetres between solid timber floorboards for movement. Secret-nail through the tongue so the fixing is hidden.
- Suspended timber floor ventilation
- Provide air bricks or vents in the external wall so air moves under the floor. This keeps timber dry and prevents rot and fungal growth.
- Stud partition centres
- Timber or metal studs are set at 400 or 600 millimetres centres to suit board widths and provide fixing. Insulation and sealing improve acoustic and fire performance.
- Scribing internal corners
- Cut the moulding to the profile of the adjoining surface so it fits tightly into an internal corner. External corners are mitred at 45 degrees.
- Wastage allowance
- Add a percentage to net quantities to cover cutting loss and damage. Typical allowances are five percent for timber and ten percent for sheet materials.
- Timber volume in cubic metres
- Multiply cross-section area in square metres by length in metres and by the number of pieces. This gives the order quantity for sawn timber.
- Formwork measurement rule
- Formwork is measured as the contact area between concrete and form, including soffits and sides. It is not the total area of plywood purchased.
- Toolbox talk purpose
- A short briefing before a task covering hazards, controls, PPE and responsibilities. Attendance is recorded and understanding is confirmed.
- Method statement content
- It sets out the sequence of work, plant, materials, supervision and safety controls. It is prepared with the risk assessment before work starts.
- Current drawing revision
- Always work from the latest issued revision. Confirm changes in writing and mark up superseded drawings so outdated information is not used on site.