© Boardworks Ltd 20051 of 23 Resistant Materials Components These icons indicate that teacher’s notes or useful web addresses are available in the Notes

© Boardworks Ltd 20051 of 23

Resistant MaterialsComponents

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Learning objectives


Lea

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es To understand how fixings are used to join materials, and to be able to select an appropriate fixing for a given task.

To understand how different nails and screws are used.

To understand how rivets and bolts are used.

To understand why and how hinges and handles are used.


It is unusual for a product to be made from only one piece of material.

Usually you will have to join several components together to make a product.

A range of fixings are available to complete a product, such as fasteners, fixings, hinges, springs, etc.

What components do you think have been used to make this office table and chair?

Components


They are used because they are:

Nails are the most common forms of fixing used with wood.

Nails are sold in standard forms by length and type.

inexpensivequick to useeasy to put indifficult to extract.

round wire oval wire lost head

panel pinclout upholstery nail

Nails


Types of nails


More grip is possible if the nails are hammered in at an angle – this is called dovetail nailing.

When a nail is hammered into a piece of wood:

the nail forces the fibres of the wood apartthe lines of grain move and grip the nailif the nail is pulled, the fibres of wood grip the nail more firmly.

Nails


If a nail is placed too close to the edge of a piece of wood, it will split.

Oval nails should be used with the oval running along the grain to prevent splitting.

Too many nails along the line of grain will also cause splitting.

Problems with nails


gauge length type of head material.

Screws are commonly used where the fixing may need to be temporary. They are used because they are:

Screws are sold in standard forms by:

strong easy to use easy to remove.

twinfast screw

countersunk

round head

raised head

slotted

phillips

pozidrive

Screws


Types of screw heads


1) Drill a clearance hole through the top piece of wood.

2) Drill a pilot hole in the other (or use a bradawl).

3) Countersink if appropriate.

Joining two pieces of wood:

Pilot and clearance holes


Brass screws are not as strong as steel and can break when being tightened.

If joining hardwood, create the thread by using a steel screw first, take it out and then put in the brass screw.

Chipboard screws are designed for joining fibrous chipboard and have a very coarse thread.

Special screws


quick inexpensive traditional.

snap head

countersunk head

flat head

bifurcated rivet

Rivets are used to join metal together permanently.

Rivets are:

Rivets


Pop rivets, also known as blind rivets, were designed to overcome the problem of riveting two pieces of material together when access was only possible from one side.

Pop rivets are hollow with a steel pin through the centre. A hole is drilled through both pieces. The rivet is placed in a pop rivet gun and pushed through the two materials.

The handle is pulled and the steel pin is pulled through the hollow rivet until it deforms the rivet and eventually snaps.

steel pin

rivet

Pop rivets


Metals are often joined temporarily using nuts and bolts.

Nuts and bolts allow you to assemble your product quickly and easily.

They also allow for disassembly for maintenance and repair.

Nut, bolt and washers

The usual head for a bolt is a hexagon.

This is tightened using a spanner, which may be open ended or ring.

Nuts and bolts


There are many different types of nuts available.

Hexagonal nuts can be tightened with normal spanners.

Wing nuts can be tightened by hand.

To prevent nuts from coming undone you may choose a nylock (a nylon insert inside a nut grips the thread) or a castellated nut with a split pin to prevent it coming undone.

wing square hexagonal castle nylock

Nuts


Tightening hexagonal nuts and bolts against any surface will cause damage. Washers are used to protect the surfaces being clamped.

Plain washers are inexpensive.

Locking washers prevent nuts from coming undone in service.

Tab washers ‘lock’ a nut in place to prevent it from coming loose.

Spring washers are able to withstand vibrations.

plain lock tab spring

Washers


Large wooden structures may need strengthening.

An inexpensive and convenient way of adding strength to the joints is to screw a metal plate to the wood.

Angle plates and tee plates are made from mild steel.

Strengthening plates


Knock-down fittings (KDF) create strong joints easily and quickly. They use temporary joints that can be taken apart and the furniture ‘knocked down’.

Knock-down fittings

A simple means of assembling knock-down furniture is to use nylon blocks with holes drilled in them.


Knock-down fittings using allen screws or threaded machine screws, which connect with threaded metal dowels, are used in assembling flat pack furniture such as bed frames and desks.

Knock-down fittings


Many different types of hinges are available.

Hinges allow doors to open and close easily, and support the door as it opens. One side of the hinge is screwed onto the door frame while the other is screwed to the door itself.

Where would you expect to see hinges like the two pictured here?

Hinges


Handles allow doors to be opened easily. There are many different types of knobs, pulls and handles. The handle you choose may depend on who the user is, and how much weight they will need to use the handle, as well as what the handle looks like.

Where would you expect to see handles like the ones pictured here?

Knobs, pulls, handles


Components quiz


Key points


Key

po

ints

Fixings are used to join different parts of a product.

Nails are used to permanently join pieces of wood.

Screws are used when fixings may need to be temporary.

Rivets are used to join metals permanently.

Nuts and bolts are used to temporarily join metals.

Knock-down fittings create strong joints which can be easily taken apart.

Hinges and handles come in many different types, and allow doors to open easily.

Documents

© Boardworks Ltd 20051 of 23 Resistant Materials Components These icons indicate that teacher’s notes or useful web addresses are available in the Notes