2.6 Efficient Drawing Layout and Sequencing

Page 36

equal parts and from this find

points 2 to 6 and draw the

perpendiculars to the base line.

Lay off 600mm from point s

to point p, which may be

inside or outside the

semicircle, and draw the

perpendicular at p and lay off

the respective value of x found

in the chart and place at point

Q.

From point Q draw the

connecting line S intersecting

the perpendiculars of the

semicircle at points A to G.

The line segments aA, bB, etc.

are the parts needed for the

development in figure 2.

In figure 2 the allowances for

the male/female seam and for

the overlap are already added.

The allowances for the beaded

pieces in the elevation can be

added at the base line or better

still at the mitre lines as done

here.

2.6 Efficient Drawing

Layout and Sequencing

of Layouts

Today it is customary in the

insulating industry to develop

fittings according to section

2.5 above. When cutting the

plates to size, metal waste and

cutting can be reduced by

alternatively laying the various

segments one under the other.

It is very important to nest the

various patterns together to

maximise economy of

materials. Also the connection

of the individual segments is

almost only made with a

beaded piece and counter

piece as shown under the arc

in figure 1. The average

allowance for the beaded

pieces is 8 mm, in other words

4 mm for half the

development. For smaller

pipes and small beaded pieces

3mm is enough of an

allowance.

Refer to Module 1 – Unit 9 –

Metal cladding assembly

work.

Refer to Module 1 – unit 5 –

General allowances for

insulation and

cladding.

Refer to module 1 – unit 4 –

Notching, folding and

joining.