Transcript Slide 1

Level 3 Diploma in Bench Joinery
Unit 309: Manufacture shaped doors and frames
Identify different construction methods for forming
curved components
© 2013 City and Guilds of London Institute. All rights reserved.
1 of 16
Level 3 Diploma in Bench Joinery
Identify different construction methods for forming
curved components
Construction techniques used with curved components
Selecting correct construction techniques when designing shaped
doors and frames
Advantages and disadvantages of the different methods
© 2013 City and Guilds of London Institute. All rights reserved.
2 of 16
Level 3 Diploma in Bench Joinery
Curved heads
The forming of curved head components for doors and frames is
usually carried out in one of the following three methods:
1. solid sections
2. built-up sections
3. laminated sections.
© 2013 City and Guilds of London Institute. All rights reserved.
3 of 16
Level 3 Diploma in Bench Joinery
Grain direction
Whichever construction method is chosen, the direction of the grain
should be a major consideration in your choice.
The grain needs to run along each component instead of across the
component.
Grain that starts to run across the component is referred to as short
grain.
© 2013 City and Guilds of London Institute. All rights reserved.
4 of 16
Level 3 Diploma in Bench Joinery
Problems when using short-grained timber
construction
1. When short grain is present in the component there is an increased
liability that the timber will break very easily across the grain.
2. This risk is increased if loose-grain timber is being used or if slight
splits are present.
3. Machining short-grain on a spindle moulder or router will increase
the risk of timber breakages while machining and thereby increasing
the risk of injury.
4. More complicated joint construction may be required to overcome
short-grain breakages.
© 2013 City and Guilds of London Institute. All rights reserved.
5 of 16
Level 3 Diploma in Bench Joinery
Solid section construction
The shaped section of the frame is constructed using solid timber
sections that are butt-jointed together.
This form of joint is call a heading joint.
The more individual sections there are, the more joints there are, but
less short grain in each section.
© 2013 City and Guilds of London Institute. All rights reserved.
6 of 16
Level 3 Diploma in Bench Joinery
Solid section
Advantages
The easiest form of construction
to use
Short construction time
Less material required
© 2013 City and Guilds of London Institute. All rights reserved.
Disadvantages
Can have lots of short grain
Forms a weaker joint than other
methods
Often requires a more
complicated and time-consuming
joint to be produced
7 of 16
Level 3 Diploma in Bench Joinery
Grain direction
The direction of the grain is vital to ensure strong doors and frames are
produced.
Short grain is more liable to break apart when it comes into contact with
machine tooling.
Poor choice in timber selection and grain direction could result in an
increased risk of injury and damaged components.
The grain should run down the length of the timber section as much as
possible.
The tighter the curve, the more sections are required to prevent
excessive short grain.
© 2013 City and Guilds of London Institute. All rights reserved.
8 of 16
Level 3 Diploma in Bench Joinery
Positioning templates for correct grain direction
Correct grain
direction running
down the length of
the template
Templates laid
on timber
© 2013 City and Guilds of London Institute. All rights reserved.
Incorrect grain
direction running
across the template
9 of 16
Level 3 Diploma in Bench Joinery
Solid timber joints
Short grain could cause timber to break,
Butt joint or heading joint used to join
giving a poor finish.
sections together.
Increased risk of injury while profiling
This is a weak joint but simple to produce.
short-grained sections.
© 2013 City and Guilds of London Institute. All rights reserved.
10 of 16
Level 3 Diploma in Bench Joinery
Staggered heading joint
Advantages
Shaped components built up in
layers gives increased strength
Disadvantages
More difficult to produce
More time-consuming to produce
No single joint line giving
additional strength
More timber required to produce
finished frame
Less short grain
Less risk of injury
More difficult to get all joints tight
together
Less likely to break along the
short grain
© 2013 City and Guilds of London Institute. All rights reserved.
11 of 16
Level 3 Diploma in Bench Joinery
Staggered heading joint
Staggered heading joint built up in three layers
If possible, have each layer the appropriate thickness to correspond
with profile positions.
Always ensure joints for each layer do not line up.
© 2013 City and Guilds of London Institute. All rights reserved.
12 of 16
Level 3 Diploma in Bench Joinery
Laminated or glulam construction
Laminated construction requires the gluing of multiple thin layers of
timber, each about 3–5mm thick, to build up to the required thickness.
These laminates are glued together and cramped around a jig to the
required shape.
Try to gauge the thickness so some of the joints fall in line with the
moulding profiles, if possible.
In reality, this will prove quite difficult as you will be working with
multiple and more layers than the profile is likely to have.
© 2013 City and Guilds of London Institute. All rights reserved.
13 of 16
Level 3 Diploma in Bench Joinery
Laminated construction
Advantages
Disadvantages
Strong
Requires the construction of a jig
The grain will always run along
the curve
Requires the need for a
substantial amount of cramps
No heading joints so less likely to
have joints
Very time-consuming
No short grain
Difficult to get good quality timber,
without knots and holes, down to
required thickness
Thin laminated timber is more
likely to split while bending,
unless good quality
© 2013 City and Guilds of London Institute. All rights reserved.
14 of 16
Level 3 Diploma in Bench Joinery
Laminating jig
© 2013 City and Guilds of London Institute. All rights reserved.
15 of 16
Level 3 Diploma in Bench Joinery
Any questions?
© 2013 City and Guilds of London Institute. All rights reserved.
16 of 16