PG.562-674Sketching-etc

Why are assembly drawings frequently shown with parts cut in section?

Answer: To clearly show the internal function of the machine and to help locate parts and fasteners inside the assembly.

To clearly show the internal function of the machine and to help locate parts and fasteners inside the assembly.

When parts in a sectional view are too thin to show proper hatching (such as sheet metal, gaskets, packing, or joints), how are they represented?

They are shown as a thick solid line.

When two thin adjacent parts (such as sheet metal and a gasket) appear next to each other in a sectional view, how should they be drawn for clarity?

A small space should be left between them.

In a sectional view of an assembly, why do adjacent parts usually have hatching that changes direction?

To clearly show where one part ends and the next part begins.

What does the cutting-plane line on any sectional view indicate?

Exactly where the imaginary cut through the object has been made.

True or False: In a full sectional view, hidden lines inside the object become visible as solid object lines.

True

True or False: The main purpose of any sectional view is to hide internal features so the drawing stays simple.

False

When creating a sectional view of a part that has slanted or angled surfaces, how should the angle of the hatching lines be chosen?

The angle of the cross-hatching lines should be adjusted to fit the shape of the part.

In assembly drawings, what is the recommended practice for choosing cross-hatching patterns for different materials such as steel, aluminum, copper alloys, or friction material?

Each material has its own distinct recommended pattern so parts can be easily identified.

What is the recommended cross-hatching pattern for steel and cast iron (cast iron only in the U.S.) in assembly drawings?

Evenly spaced 45-degree lines.

What is the recommended cross-hatching pattern for aluminum and aluminum alloys (or steel in the U.S.) in assembly drawings?

Evenly spaced lines at a different angle or spacing than steel or cast iron.

What is the recommended cross-hatching pattern for copper and copper alloys (brass and bronze) in assembly drawings?

Evenly spaced lines in a distinct direction or spacing.

What is the recommended cross-hatching pattern for friction material in assembly drawings?

A dense, closely spaced cross-hatch or special pattern to indicate friction material.

How is various wood shown in a sectional view on general construction drawings?

With wavy grain lines or a wood-grain symbol.

How is concrete represented in a sectional view?

With small circles, triangles, and dots to show the aggregate.

How is glass or any transparent material shown in a sectional view?

With short diagonal lines or a light hatching pattern.

What is a full section?

A view obtained by passing a cutting plane completely through the object so that internal features become visible as solid object lines.

When is a half section typically used?

On symmetrical objects, where one half is shown cut in section and the other half is shown as an exterior view.

True or False: The cutting-plane line for a half section is identical to the one used for a full section.

True

True or False: A half section is only used on asymmetrical parts.

False

Consider a symmetrical round part shown with one half cut away to reveal the inside while the other half shows the outside shape. What type of section is this?

Half section.

What is an offset section?

A section in which the cutting plane is bent or offset at 90-degree angles to capture features that do not lie in a single straight line.

In an offset section, are the bends or offsets of the cutting plane shown as lines in the final view?

No – the offsets are imaginary and features are aligned as if they all lie on one flat plane

What is an aligned section?

A section view in which the cutting plane is bent to pass through angled features, and those features are revolved or aligned into a flat plane so their true shape is shown.

Why is an aligned section often preferred over a true full section for parts that have angled spokes or ribs?

It shows the true shape and location of the angled features clearly without distortion.

Consider an irregular part where the cutting plane must bend at right angles to reach several important features that are not in a straight line. What type of section is used?

Offset section.

When a cutting plane passes directly through a web or rib on a part, should the web or rib be cross-hatched?

No – webs and ribs are left unhatched.

True or False: Leaving a web or rib unhatched prevents the drawing from looking as if the part is solid.

True

What is the difference between true projection and preferred (conventional) representation in sectional views?

True projection follows exact geometric rules; preferred (conventional) representation simplifies or aligns features for clarity and is the standard used in industry.

True or False: Industry drawings usually follow preferred (conventional) representation rather than strict true projection.

True