Title: Joining Techniques Wood, Metal and Plastic
1Joining TechniquesWood, Metal and Plastic
2How to join Wood.
- There are 4 main ways to join wood an adhesive,
a joint, a nail or screw or using a knockdown
fitting. Common wooden products that you use
every day will incorporate some of the joining
techniques above.
3Gluing
- The majority of the time Polyvinyl acetate (PVA)
wood glue will be used to join wood. PVA glue is
used in the workshop every day and is the glue
you would use to make paper Mache.
4Nails and screws
- There are many types of nails and screws to fit
your needs. Some common ones are below.
Round head
Oval head
Countersink or flathead
5Knock-down fittings
- Knock-down 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.
6- Other glues that could be used would be
Superglue, epoxy resin, Hot glue, and a number of
different resin glues Phenol formaldehyde resin,
Urea-formaldehyde resin. - Before these modern glues the glue of choice was
animal glue or hide glue. It is manufactured from
rendered collagen from the skins (hides) of
animals. It is chemically similar to edible
gelatine and is non-toxic if ingested. Hide glue
is still used today in specialized applications
musical instruments (lutherie), for replica
furniture, and for conservational-grade repairs
to antique woodwork.
7Wood joints
- Butt Joint
- The most simple and easiest to make wood joint is
the Butt joint. The joint relies solely on the
strength of the glue to hold it together.
8Housing Joints
- Â What is a Housing joint?
- Housing joints are used when two pieces meet at
right angles on their narrow face. A shallow
trench is cut across the grain of the vertical
member, the shelf or panel is then glued into a
simple straightforward housing and all the loads
are transferred to the sides of the unit. Pins
can further strengthen the joint. - Â
- What are the advantages of this type of joint?
-       Simple to make.
- Â Â Â Â Â Â Strong.
- Â Â Â Â Â Â In its basic form only one component has
to be shaped. - Â
- What are the applications for this type of joint?
- Used for fixing shelves to vertical panels in
deep cabinets, bookcases, storage units and
boxes, or for drawer fronts and carcase/frame
construction.
9Types of Housing Joints
- Â Through housing joint
- The trench of the though housing goes fully
across the piece of wood so the joint can be seen.
10- Stopped housing joint
- For decorative effect, the trench of the housing
is often stopped short of the front edge of the
side panel by some 9 - 12 mm. No part of the
joint is visible from the front because the joint
is completely concealed. This is particularly
important where a high quality finish is required.
11Mortise and tenon jointsÂ
-  What is a Mortise and tenon joint?
- The mortise and tenon is one of the most common
joints used by woodworkers and is the traditional
corner joint for sturdy frames. - Â
- What are the advantages of this type of joint?
- Â Â Â Â Â Â Neat and very strong.
- Â Â Â Â Â Â Large surface area for gluing.
- Â Â Â Â Â Â It cannot wobble.
- Â Â Â Â Â Â Is difficult to pull out.
- Â Â Â Â Â Â Most of the joint is hidden in the
timber. - Â
- What are the disadvantages of this type of joint?
- Â Â Â Â Â Â Can be fairly difficult to mark out and
cut. - Â Â Â Â Â Â Poor resistance to tension, especially if
badly fitted. - Â
- What are the applications for this type of joint?
- Used where maximum strength is important in
window, door, chair, mirror, bed and table frames
and frame-and-panel cabinets or external work
like garden or street furniture (seats, tables
etc)
12Through mortise and tenon joint
In a through mortise and tenon joint the end
grain is visible and the joint needs accurate
cutting for good appearance.
13Haunched mortised and tenon joint
In order to include a strong joint at the frame,
a haunch is introduced to the joint. The haunch
prevents the frame from twisting and makes it
firmer, giving it added strength. It also
increases the gluing area.
14Stopped mortise and tenon joint
This is the best joint for external work as most
of the joint is protected from the weather by
tenon shoulders. The joint is strong and
concealed and used in furniture construction
where a high- quality finish is required. The
stopped mortise and tenon joint is a good looking
joint because the tenon of this joint does not
show on the outside face. The depth of the
mortise should be three-quarters of the thickness
of the wood being joined.
15Dovetail
- What is a Dovetail joint?
- Dovetails are the strongest of all joints. The
joint is made up of interlocking wedge-shaped
elements called pins and tails that resist the
forces applied to the joint. This joint looks
attractive and, if well made, the decorative
quality can be used to enhance projects. In other
projects the joint can be hidden completely.
Dovetail joints work best when in tension. For
example, the most common application of the
dovetail joint is in drawer making as the
strength of the joints tails and pins resist the
pulling forces applied to the drawer. Dovetails
are so strong it is rare to see a drawer that has
broken as a result of joint failure, even when
put under frequent stresses.
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17Finger joint
A finger joint or comb joint is a woodworking
joint made by cutting a set of complementary
rectangular cuts in two pieces of wood, which are
then glued. To visualize a finger joint simply
interlock the fingers of your hands at a ninety
degree angle hence the name "finger joint." It
is stronger than a butt or lap joint, and often
contributes to the aesthetics of the piece.
18Other common wood joints
Lap joint
Dowel joints
19How to join Metal.
- There are a number of ways to join Metals. Some
common joining techniques are, rivets, adhesives
and thermal joining.
Women riveting the side of an airplane panel at
Ford Motor Companys Willow Run bomber assembly
plant in Ypsilanti, Michigan, August 23, 1944.
20Riveting
                                                                                                                     Â
- Rivets are used to join plates together and they
have been used for hundreds of years. Before the
widespread use of welding, rivets were used in
heavy industries such as ship building. The steel
plates used to build ships such as the Titanic
and the naval Dreadnaughts of World War One were
held together by steel rivets. Rivets have
largely being replaced by techniques such as
welding and brazing. However, joining plates
together with rivets is still a useful technique
especially if the plates to be joined are quite
small. Cold rivets are still used in school
workshops although the modern pop-riveting
technique is more popular.
Riveting video
21Adhesives
- Glues like in wood can also be used with metals.
Glues like the epoxy resin can also be used to
glue together sections of metal.
22Thermal joining
- Thermal joining means using heat in order to join
metal together. Some methods of joining metal
together using heat are welding, soldering and
brazing.
23Arc Welding
Arc welding is a type of welding that uses a
welding power supply to create an electric arc
between an electrode and the base material to
melt the metals at the welding point to create a
permanent joint.
24Brazing
- Brazing is a metal-joining process whereby a
filler metal is heated above melting point and
distributed between two or more close-fitting
parts by capillary action. The filler metal is
brought slightly above its melting temperature
while protected by a suitable atmosphere, usually
a flux. It then flows over the base metal (known
as wetting) and is then cooled to join the work
pieces together. It is similar to soldering,
except the temperatures used to melt the filler
metal are higher for brazing.
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26Soldering
- Soldering is a process in which two or more metal
items are joined together by melting and flowing
a filler metal (solder) into the joint, the
filler metal having a lower melting point than
the adjoining metal. Soldering differs from
welding in that soldering does not involve
melting the work pieces. Soldering is commonly
used in electronics to create circuits.
Soldering video