In the next chapter you will further develop your drawing skills. You will have to make various drawings of a staircase and wheelchair ramp.
In this chapter, you will make accurate isometric and orthographic drawings with instruments.
Nelson Mandela High School in the Eastern Cape is brand new. It has a beautiful new community hall with a stage. Learners use the stage for dramas, fashion shows, music events and gospel choir performances. The architects designed great lighting and sound systems, but they forgot one very important thing: to provide access for wheelchairs so that disabled people can get onto the stage.
The principal asked the Grade 9 Technology students to design a mobile staircase and a wheelchair ramp that can be put in front of the stage.
Figure 1
Figure 2
Stairs and a ramp
Nelson Mandela High School has a new community hall. A staircase and wheelchair ramp is needed for the stage in the hall. The principal made a list of things that should be kept in mind when designing the staircase and wheelchair ramp.
If you look at the picture on the previous page, you will see what a ramp is.
These are called specifications.
The specifications for the staircase and wheelchair ramp are:
The stairs and ramp must be made in one unit so that it can be moved.
The unit should fit in front of the stage so that people can walk onto the stage and wheelchairs can go up and down.
The stage is 400 mm high.
The stairs should be wide enough for two people, about 1 200 mm.
There should be three steps of the same size.
The flat part of each step is 800 mm long.
The ramp should be wide enough for one wheelchair 1 000 mm.
The slope of the ramp should be 2 433 mm long.
The ramp is at a 10 slope.
The base of the ramp should be 2 400 mm long.
The ramp should have a handrail to prevent wheelchairs from falling off.
To help you imagine what the combined staircase and ramp will look like, you can make a few drawings.
Make a rough drawing to show what you think the combined staircase and ramp should look like. Make your drawing on a clean page, and make it big enough to fill the page.
Dimensions are given in the above specifications. Write the dimensions in the correct places on your drawing.
An isometric drawing can help you to see more clearly what your idea would look like when it is built. To make an isometric drawing, draw all the vertical lines of the object at 90 to the base, and all the horizontal lines at 30 to the base. You can use isometric grid paper to help you do this.
Isometric drawing
In Chapter 1, there is an isometric drawing of a staircase. What do you think an isometric drawing of the ramp would look like? It could look a bit like a slice of birthday cake!
Figure 4
Make a sketch of the wheelchair ramp that looks like the slice of cake above, on the top part of the isometric grid on the next page.
Now make a better sketch on the bottom part of the page.
A sketch is a rough drawing that helps you to quickly put your ideas onto paper. It makes it easier to think about what you are designing.
You do not need to use a ruler or exact measurements.
Look at the list of specifications at the beginning of section 2.1 and write the following on your drawing:
the height of the ramp,
the length of the sloping part of the ramp,in other words the distance from A to B on the drawing on the right,
the length of the base,
the width of the ramp, and
the 10 ° angle
Figure 5
The plan in orthographic drawings
Make a sketch of the staircase on the isometric grid below. Remember it has only three steps. Look at the list of specifications and write the following on your drawing:
