Mr Dowling is here to help Revise in the comfort of your home

Remember You need to use the table of information I gave you previously to add to your subject knowledge.

Not just glue. Adhesives PVA (wood), contact adhesive (almost everything), epoxy resin (everything pretty much) and Tensol Cement (joining acrylic) PVA – Very strong, as long as it is a good fit. Held under pressure. Most types are not waterproof. Contact Adhesive – Large sheets materials, thin layer on both sides, left to dry for 15mins. Once together no repositioning. Epoxy Resin – versatile but expensive. Dry and clean surfaces. Two parts, a resin and a hardener. Takes 2 or 3 days to reach full strength. Roughen smooth surfaces Tensol Cement – Clear and evaporates easily. Not very strong so try larger area as possible. Remember – Solvent based adhesives give off harmful fumes.

Joining Methods Two main types – Temporary Permanent Tapping and threading, Nuts, bolts and washers Screws Knock-down fittings Permanent Nails Halving joint Butt joint Rebate joints Housing joints Mortise and tenon joints Dowel joints Brazing Welding Rivets – snap and pop

Join stuff Tapping and treading – Both on metal and plastic. Tapping is the process of cutting an internal (female) screw thread. Drill hole, smaller than the tread and use a tap to cut the thread, Three stages, taper, second and plug. This gradually cuts a tread – 1/2 turn clockwise followed by a ¼ turn anti-clockwise to release swarf. Threading is an external screw (male) – uses a split die held in die stock. Same cutting action as a tap. Nuts, bolts and washers – a collar with a threaded hole. Generally hexagonal but also wing and square. A locking nut has a nylon insert which stops it working loose. Bolts are often made from high-tensile steel. Use a washer between the head and the nut to spread the load.

More joining Screws – Wood screws are a neat and reliable method of joining wood. Screws are classified by length, gauge, type of head & materials. Brass or steel. Two head types – countersink and round head. You need to follow a three stage process – Clearance hole, a pilot hole and a countersunk to the clearance hole. Knock-down fittings – allow joints to be made quickly and easily. Taken apart easily to allow flat-packed furniture. Used in kitchens and furniture. Nails – Quick method of joining wood. Grip by forcing the fibres of the wood away from the head. Should be three times longer than width of the wood. Metal Joining – Soft soldering – for brass, copper and tinplate. Flux is used to aid flow of solder. Brazing – gas torch – flux (borax) is mixed with water and spread around the joint. Only mild steel as it is too hot at 875C.

More Joining together Welding – melts two pieces of metal – as strong as the original material. MIG and Arc welders. Uses flux and amps to heat the metal to join two pieces together. Rivets – sheet metal, soft iron with a range of head shape. Pop rivet uses a gun. Drill a hole, and using a snap & a hammer – shape the head on the other side – look it up on youtube if I am confusing you. Look up pop riveting as well.

Material processing and forming Two types – deforming and reforming. Deforming – such as laminating and vacuum forming to change the shape without changing the state. Reforming – casting – goes from solid to liquid or plasticised state. Sand casting, injection moulding, drilling, turning (wood and metal), blow moulding, vacuum forming, extrusion (plastic and metals) and wood laminating. Know these and be able to talk about steps.

Sand Casting Complex shapes, car engine parts and kitchen and bathroom taps. Casting aluminium in sand moulds is cheap and simple. 1: Make a pattern of the required product (a mould) 2: Encase the pattern in moulding sand 3: Split the sand box and remove the pattern to leave an empty cavity 4: Pour molten metal into the mould 5: When the metal solidified and cooled, remove the product. Outcome is dependent on quality of mould. You will need a runner and a riser to allow air to escape. Look on video sites.

Drilling Very common process – know the difference between hand, pillar and cordless. Most need a chuck key to tighten or loosen the drill bit. Wood turning – Make wood circular – fruit bowls & Spindles. Preparation is essential – never turn wood that has not had the corners planes off. Make sure the work is centred and that the tool rest is not very far from the work. Metal Turning – on a centre lathe – know the different processes. Used for turning metal. Plastic moulding can be split into Blow Moulding, extrusion and injection moulding and Vacuum forming. Heat is used to change thermoplastic into a new shape. I would suggest you understand Injection moulding first and then blow moulding and extrusion is only slightly different. Be able to draw the injection moulding machine

Diagram This changes from a mould to a die, to a hollow mould for the three different types. The difference between the three are injection moulding is for solid shapes, Extrusion is for uniform shapes such as Rainwater pipes and run continuously Blow moulding is for hollow product like bottles All heat plastic to molten and then forced in to another shape. Metal extrusion is done with Aluminium and copper

Vacuum Forming Packaging items, Easter-egg containers, yoghurt pot, trays etc. PVS, HIPS, acrylic. Know the process of mould, plattern, heater etc. Rules for a good mould – all vertical surfaces are slightly tapered (5 degrees), round off sharp corners, vent holes to avoid pockets of air. Internal edges rounded off and avoid sharp corners. No cut-in as the mould can not be removed. Wood laminating – thin sheets of wood, with glue in between are formed using a jig and pressure (can be a big bag or a mould. It industry the same process but on a much bigger scale.

Scale of production Three types – one-off, batch and mass. Look at the table but generally the difference are the type and size of machinery used. The level of skills required get less as the amount is produced. More computers and more robots are used as the amount are being produced. Wasting – Not your time Produces waste or unusable material by either cutting bits out or cutting bits off. Saws, planes, chisels, files, drills and abrading tools. Planes are used for smoothing wood flat and to size. Chisels – know the four types and what they are for. Firmer, bevel-edge, mortise and gouge. Cold chisels are used to cut sheet materials, by shearing across it. Abrading tools – such as rasp and surform for moving big stuff. Files – cross-filling and draw-filling, Cross for removing waste rapidly and draw for removing marks.

Marking out and measuring Know the different types as this may well be in the first part (i.e. The easy stuff). Rules for measuring Squares for marking (mitre for 45 or 135 degree), try square for right angles (perpendicular) Engineer’s square for metal and plastic. Gauges - Marking, mortise and cutting gauge. Used to mark lines parallel to the face edge. A stock that slides up and down depending on the measurement. A cutting gauge is used to cut across the grain and has a blade instead of a pin (as a Marking Gauge does) Scribers – scratch the surface of metal and plastic. Engineers blue on metal used to help see the marking. Punches – Centre are used to make an indent on the surface where holes are to be drilled in metal. Dot punches are used for centres and differ on the angle of the tip.

Honestly nearly there Templates – used when a number of identical shapes need to be marked out. Micrometers – specialised instrument used to take a very accurate measurement. Metals – two types – ferrous contains iron and and non-ferrous that does not contain iron. One rusts the other doesn’t, one is magnetic the other one isn’t.