tech 104 – technical graphics communication week 4: multiview drawings - 2

TECH 104 – Technical Graphics Communication

Week 4:

Multiview Drawings - 2


Week 4: Multiview Drawings 2

Here’s what we talked about last time…..



Here we can see all the principle views of an object as the glass box is unfolded.

It is easy to see that some of the principle views have more detail through the use of object (visible) lines than others.

Always choose views that have the least amount of hidden lines in them and show the most detail.



Surfaces will appear as edges at times. Edges may be foreshortened (shorter than normal), or “True Length” (TL).



Oblique edge lines are created by oblique surfaces.

These are surfaces that are neither true shape or true size in any principle view.



Holes and cylinders may appear “True Shape and Size” (TSS), or foreshortened depending on the view in which they appear. (Foreshortened circles will appear as ellipses.)



Let’s now take another look at multiview drawings in more detail…..



We place hidden lines in a drawing to do the following things:

1. Show hidden features

2. Clarify the position and shape of features

3. Make the “plate” more readable

(NOTE: The term “plate” refers to a finished drawing.)



Depending on the application, hidden lines will either touch other hidden lines, or pass over them

Note how hidden lines follow specific rules as to how they are to be laid out.



Center lines are used to show the theoretically perfect center of holes, arcs, cylinders and bolt circles*.

*A “bolt circle” is used to position holes or cylinders in a circular pattern.



Center lines extend past the objects they are used to describe.



Center lines will break their normal shape of a long dash interrupted by a short dash if an object or hidden line needs to take precedence.

In these examples, only a short dash is used to show the center line.



When only a short dash is used to represent a center line, there must be some space shown between the object and the short dash.



Machined Holes:

Here, we can see many examples of the different styles of holes that are used in manufacturing.

Each has a specific layout when it comes to displaying them with hidden lines.



Rounds and Fillets are used to relieve stress and finish edges on manufactured goods.



“Runouts” are used to show the topology of cast parts.



More examples of runouts.



“Intersections” are used to show the union of two or more cylinders. Several types of examples are shown here.



Intersections between cylinders and prisms.



Partial views are often used to simply symmetrical objects. or to........



…focus on only part of the object.



“Revolved” views are used to give a clearer representation of an object. We actually “draw the object incorrectly to make it easier to understand”. Here, webs have revolved to 12, 3 and 6 o’clock positions to make the view easier to visualize.



Here, the correct view of the object will appear to be a mass of hidden lines in the right side view.

By representing only the 12 & 6 o’clock positions, we create a view that is easier to understand.

Further notes would be added to the front view during dimensioning.



Arms and spokes are often revolved to create a view of the object that is easier for the human brain to visualize.

CAD Commands used to create “protos” A, B & C:

LIMITSGRIDSNAP LAYER



Sketching Assignments

Given two orthographic views of an object, your task is to create the missing view. The given views may also have some missing lines that need to be added.




#27




#40


#41



#48


Week 5:

Auxiliary Views


tech 104 – technical graphics communication week 4: multiview drawings - 2

Documents

multiview drawings

hidden lines

center lines

hidden features

oblique edge lines

short dash

use of object visible

true shape