Knockdown Fittings (KD Fittings)

Knockdown (KD) fittings are mainly used to assemble flat pack furniture or for assembly by the user. They are used within kitchen units or self-assembly furniture. Knockdown (KD) fittings are often plastic fittings which can be joined together with one screw or bolt. A simple knock down fitting is a ‘block joint’. Block joints are simply plastic blocks that take screws in different directions.

Knockdown fittings are those that can be put together easily, normally using only a screw driver, a drill, a mallet/hammer and other basic tools. They are temporary joints although many are used to permanently join together items such as cabinets and other pieces of furniture that are purchased in a flat pack from such stores as Argos and Ikea.

PLASTIC CORNER BLOCK (FIX IT BLOCKS)

The corner block is pressed against the two pieces of material (normally timber based). Screws are used to fix the block into position. This type of joint is used to fit modern cabinets such as those found in a kitchen or bathroom. It is a relatively strong joint although it has the advantage that it can be dismantled using a screwdriver.

NATURAL WOOD FITTING (SQUARE SECTION BATTEN)

A piece of material such as softwood or hardwood can be drilled and screws can be passed through these holes. This gives a cost-effective knockdown joint. The screws are normally countersunk into the knockdown fitting.

TWO BLOCK FITTING

These are made from plastic. A bolt passes through the first fitting into the thread of the second. As the bolt is tightened it draws the two fittings together. The pins help keep the fitting straight. This gives a very strong joint and it can be dismantled using a screwdriver.

RIGID JOINT

These are normally moulded in plastic which makes them strong. Screws pass through the four holes which hold the sides at each corner firmly together.

SCAN FITTINGS

These are strong enough to be either permanent or temporary joints. The cylinder is inserted into the first side of a cabinet in a pre-drilled hole. The screw is then pushed through the hole in the second side until it meets the cylinder. It can then be tightened with a screw driver until both sides of the cabinet pull together. These are frequently used for table and bed frames.

CAM LOCKS

The disk fits into a recess in the first side of the cabinet. It rotates by inserting a screwdriver into the slot in its side. The shaft is screwed into the second side of the cabinet.

The collar of the shaft is passed through the hole in the second slot in the disk. When the disk rotates the shaft is locked in position. This keeps both sides of the cabinet locked together.

In order to see how these work you will need to look carefully at the pictures.

If you can use all this then you will be in with a very good chance of getting some excellent marks.

Cutting sheet materials

Cutting large sheet materials is a difficult task even with machinery. Imagine that you are working on a project that is going to use standard size sheet of 18mm coated MDF or chipboard. How are you going to cut it up? (Apart from asking me how would you do it?)

The information below is about CHIPBOARD but the same safety and use rules apply to most other large pieces of material.

Chipboard is made by bonding together wood particles with an adhesive under heat and pressure to form a rigid board with a relatively smooth surface. Chipboard is available in a number of densities; normal, medium and high-density. Normal density is fairly soft and ‘flaky’, high-density is very solid and hard (often used for worktops and fire doors) – medium density is somewhere in between. Veneered Chipboard is widely used for self-assembly furniture, work surfaces, wall linings and partitions. High-density chipboard is often used as a basis for the carcasses of kitchen furniture, worktops, and flooring – this is hardwearing, rigid and heavy.

There are exterior grades of chipboard available but most are only suitable for internal use as all but high-density tend to soak up water like a sponge. Once water logged, chipboard tends to swell and breakdown.

Other grades available are standard, flame-retardant, flooring, and moisture-resistant.

Chipboard is normally available in 2440 x 1220 sheets (or subdivisions), finished veneered sheets are available in smaller sheets so that the four decorated edges do not need to be cut. Thicknesses range from 12 to 25 mm.

Flooring grade chipboard is marked ‘flooring’ and no other should be used. It is normally available in 2440 x 1200 and 610mm sheets and in 18 and 22mm thicknesses with tongued and grooved edges for easy laying and fixing. Before using flooring grade material check it is suitable for your floor joist spacing.

Working with chipboard

Apart from high density chipboard, the finish after cutting is generally poor. As with plywood, veneered chipboard should be cut with the saw blade going into the finish face to prevent the finish veneer chipping. To reduce the amount of damage when cutting chipboard, apply a strip of masking tape along the line of the cut and cut through the tape.

A panel, circular or jig saw can be used. When using these types of tools you should consider the following:

1. Eye protection
2. Protection from dust and particles
3. Protection from noise (prolonged noise)
4. Securing the sheet material to the bench(s)
5. Keep hands/fingers away from the blade
6. Keep blade away from cable
7. Good lighting
8. Clear work area
9. Supporting work either side of the cut

Working with chipboard

Apart from high density chipboard, the finish after cutting is generally poor. As with plywood, veneered chipboard should be cut with the saw blade going into the finish face to prevent the finish veneer chipping. To reduce the amount of damage when cutting chipboard, apply a strip of masking tape along the line of the cut and cut through the tape.

A panel, circular or jig saw can be used.

Fixing

Nails, pins and screws may be used on normal chipboard, but they should always be fixed through the chipboard and into a support. If you pin, nail or screw into chipboard, the fixings may pull out easily. With high density chipboard nails, screws and fixing can be used. The screw-holding power is improved if double-threaded or chipboard screws are used. Follow the manufacturer’s instructions for fixing special purpose boards.

Most furniture is held together with ‘KNOCK DOWN’ Fittings. You will need to know what these are. See the new section on KD fittings.

Any woodworking adhesive may be used with chipboard although when it does fail, normally the outer ‘chips’ separate from the rest of the board. Do not rely on gluing only to support heavy weight.

Finishing

Generally only laminated chipboard will give a satisfactory finish although laminate or self-adhesive decorative film can be applied to the chipboard core. Think of the chipboard as a filling in a sandwich and the laminate is the bread.

Edging (normally self adhesive) strip is available to add laminate type finish to sawn edges of pre-laminated chipboard.

It can be quicker and easier to glue or pin thin strips of real wood to the edges of cut boards. For example the edges of shelves or a desk surface.