WORKSHOP PICS - PUTTING THE CABINETS TOGETHER

SCREWING THE PLATES TOGETHER USING A DRILL AND GLUE. SHOWING EACH PLATE AND THE PLATES ASSEMBLED TO CREATE CABINETS

1.3

We are making a pair of speakers that must be constructed out of a material that is recycled or being used for a purpose that it was not originally intended for. For this we are mostly using MDF which is a type of recycled wood and we are using carpet underlay which is usually intended to line the floor beneath carpets. However, we will use it to line the insides of our speakers to insulate it against the unwanted frequinceis that cancel out.Envoronmental hazards that relate to these materials include the harmful gases produced by MDF when it is burnt or cut. This releases deadly chemicals that is in the carcenogenic glue of MDF and can cause damage to the atmosphere. Also, Carpet underlay is highly flammable and when ignited can cause physical harm and will also release large amounts of CO2 into the air.To protect against these environmental and physical hazards we are required to wear a mask that will prevent inhalation of the carcenogenic gas. Also, we use large extraction fans and open windows to remove the fumes from the work area.

2.2

2.2 Recycling options are identified for the materials to meet the requirements of the design brief.My first recycled material is MDF. MDF is an engineeredwood product made by breaking down softwood into wood fibres, combining it with wax and a resin binder, and forming panels by applying high temperature and pressure. I am reprocessing it to form a speaker by following my engineering drawing. I mark the wood and cut out the parts I need from it to create a speaker.My other recycled material is carpet underlay. Carpet underlay is used in the speaker to absorb unwanted frequencies, to stop phase cancellation which makes the speakers sound tinny. I cut it into the shape of my front and back plates and it is stapled onto the inside.

2.1

2.1 Alternative uses are identified for the materials to meet the requirements of the design brief.Carpet underlay is mainly used under carpets. It extends the life of the carpet, reduces wear on the backing, adds to the carpet's insulating qualities, and gives a softer, more luxurious feel. A good quality underlay will help maintain your carpet's appearance and greatly improve comfort underfoot. There are two widely available types of underlay - Waffle rubber and recycled polyurethane foam chip - with satisfactory qualities available in both types.In my speaker design it will be used to line the inside of my speakers. This is so it will absorb the unwanted frequencies that cancel out the good sound. It can do this because it is a soft, squishy material and it will channel the sound in a single direction out the speakers.MDF is a type of hardboard, which is made from wood fibres glued under heat and pressure. It is dense, flat, stiff, has no knots and is easily machined. Because it is made up of fine particles it does not have an easily recognisable surface grain. It may be used to make display cabinets, wall-panels, storage units, bathroom cabinets, office furniture, kitchen cabinets, panel mouldings, dining sets, fire surrounds and many more.I am using MDF because it is very dense and easy to work with. The density is important because it can insulate against unwanted frequencies and produce better sound. It will also add to the lifetime of the speakers, making them stronger and more durable.

1.2

1.2 Materials causing environmental concern are identified in relation to the task.MDF releases an odor which can irritate the eyes and nose. These compounds include aldehydes, terpenes and methanol. MDF also contains Formaldehyde. Formaldehyde is classified as a human carcinogen and has been linked to nasal and lung cancer, with possible links to brain cancer and leukaemia. Short-term exposure to formaldehyde can be fatal. Long-term exposure to low levels of formaldehyde may cause respiratory difficulty, eczema, and sensitization.MDF produces very fine dust during processing and the dust particles act as a carrier of absorbed formaldehyde to the lower airways of lungs. Wood dust and formaldehyde together have been reported to cause respiratory irritation with symptoms of dryness of throat, rhinitis and eye irritation as well as occupational skin disease. To avoid harm from the MDF keep the workshop well ventilated. When MDF is burned it can release emissions that can be harmful to the environment. The best way to reduce emissions is to carefully control combustion temperature - keep it below 800°C - and avoid using fuel with chlorine in it. Foam carpet underlay is highly flammable. It has a high fire growth rate and is also very sensitive to ignition. This could produce a problem if the speakers become overheated or the underlay is near to something hot in the workshop.

1.1

1.1 Environmental hazards are identified in relation to the task.MDF is full of Formaldehyde which can be harmful to humans and the environment. It can cause headaches, watery eyes and eventually cancer. MDF also releases other toxins into the environment. In some countries, such as Australia, wood from native forests is used to make the chips that go into MDF. This is a danger to the environment as native forests are becoming rarer and rarer. Luckily a lot of MDF manufacturers are beginning to use recycled materials, such as straw and bamboo, as sustainable alternatives to native wood.

STANDING WAVE/PHASE CANCELLATION NOTES

Standing waves are wave forms that 'stand' on the edge of the front plate, lingering around not dispersing properly. As they linger they interfere with other waveforms coming through, cancelling out waves that you want to reproduce. It produces a baseless speaker response.This is easily fixed by rounding the edges of the front plate. The standing waves will disperse outwards as they hit the edge, stopping any wave cancellation.

CARPET UNDERLAY NOTES

Carpet underlay is an absorber of unwanted frequencies inside the box. Low frequencies inside the box bounce of the wall of the box, hitting other frequencies that need to be reproduced, cancelling out the bass. The speakers sound tinny. The carpet underlay absorbs any unwanted frequencies.

BRACING NOTES

Bracing is an acoustic treatment of the box. It allows the box to stop the flexing waves forms that are reproduced inside it. The port is the 'interface' between the box and the outside. It counterbalances the moving of the voice coil by pushing out when the coil is moving in (through magnetism) and vice versa.

TOOLS LIST

TOOLS LIST
Hand Drill
Drill Press
Palm Sander
Belt Sander
Circle Cutter
Soldering Iron
RaspScissors
MalletWire
StripperCutters
PliersDrill pieces
Soldering Iron

SOLIDWORKS DESIGN JPEGS

SOLIDWORKS DESIGN TO SHOW THE SHAPE AND FORM OF MY SPEAKER CABINETS. THE RANGE OF SCREENSHOTS SHOW MY PROGRESS TO MAKING THE CABINETS IN SOLIDWORKS.

WORKSHOP PICS - TOP AND BOTTOM PLATES + BACK HOLES

CUTTING OUT THE CABINET PLATES. SHOWING THE PLATES DRAWN FIRST ON MDF THEN CUT OUT USING THE BANSAW. THE CIRCULAR HOLES ARE CUT USING A CIRCLE CUTTER.