Linear dimension in AutoCAD - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a linear dimension in AutoCAD?

A linear dimension measures the straight-line distance between two points, usually horizontally or vertically, to show the exact length or height of an object.

beginner

Which AutoCAD command is used to create a linear dimension?

The DIMLINEAR command is used to create linear dimensions in AutoCAD.

intermediate

How do you ensure a linear dimension is horizontal or vertical in AutoCAD?

AutoCAD automatically aligns the linear dimension horizontally or vertically based on the points you select. You can also specify the dimension line angle manually if needed.

intermediate

What is the purpose of dimension style in linear dimensions?

Dimension styles control the appearance of linear dimensions, including text size, arrowheads, units, and line spacing, ensuring consistency across drawings.

beginner

How can you edit a linear dimension after placing it?

You can select the linear dimension and use grips to move it or double-click to open the properties palette to change text, precision, or other settings.

Which command creates a linear dimension in AutoCAD?

A DIMLINEAR

B DIMANGULAR

C DIMRADIUS

D DIMDIAMETER

DIMLINEAR is the command used to create linear dimensions measuring straight distances.

What does a linear dimension measure?

A Straight-line distance between two points

B Radius of a circle

C Angle between two lines

D Diameter of a circle

Linear dimension measures the straight-line distance, usually horizontal or vertical, between two points.

How can you change the appearance of linear dimensions in AutoCAD?

A Using the Layer Manager

B Using the Move command

C Using Dimension Style Manager

D Using the Zoom command

Dimension Style Manager controls the look of dimensions including text size and arrow styles.

If you want a vertical linear dimension, what should you do?

A Use the DIMRADIUS command

B Use the DIMANGULAR command

C Rotate the drawing

D Select points aligned vertically

Selecting points aligned vertically will create a vertical linear dimension.

How do you edit the text of a linear dimension after placing it?

A Use the Copy command

B Double-click the dimension to open properties

C Use the Erase command

D Use the Zoom command

Double-clicking the dimension opens the properties palette where you can edit text and other settings.

Explain what a linear dimension is and how it is used in AutoCAD drawings.

Think about measuring the length of a table or height of a door in a drawing.

Describe how you can change the look and style of linear dimensions in AutoCAD.

Dimension styles help keep all measurements looking the same.

Practice

1. What does a linear dimension in AutoCAD represent?
DIMLINEAR is used to create it.

easy

A. The straight distance between two points

B. The angle between two lines

C. The radius of a circle

D. The area of a shape

Solution

1. Step 1: Understand the purpose of linear dimension

   Linear dimension measures the straight distance between two points in a drawing.

2. Step 2: Recognize the command used

   DIMLINEAR is the AutoCAD command to create linear dimensions.

3. Final Answer:

   The straight distance between two points -> Option A

4. Quick Check:

   Linear dimension = straight distance [OK]

Hint: Linear dimension always measures straight distance [OK]

Common Mistakes:

• Confusing linear dimension with angular dimension
• Thinking it measures radius or area
• Mixing up commands like DIMANGULAR

2. Which of the following is the correct command to create a linear dimension in AutoCAD?

easy

A. DIMANGULAR

B. DIMDIAMETER

C. DIMRADIUS

D. DIMLINEAR

Solution

1. Step 1: Recall AutoCAD dimension commands

   DIMLINEAR is used for linear dimensions, DIMANGULAR for angles, DIMRADIUS for circle radius, and DIMDIAMETER for circle diameter.

2. Step 2: Match command to linear dimension

   Since linear dimension measures straight distance, the correct command is DIMLINEAR.

3. Final Answer:

   DIMLINEAR -> Option D

4. Quick Check:

   Linear dimension command = DIMLINEAR [OK]

Hint: DIMLINEAR command creates straight distance dimensions [OK]

Common Mistakes:

• Choosing DIMANGULAR which measures angles
• Confusing radius and diameter commands
• Typing commands with typos

3. Given two points at coordinates (2,3) and (8,7), what will the linear dimension show as the distance?

medium

A. 10 units

B. 7 units

C. 6.4 units

D. 5 units

Solution

1. Step 1: Calculate the distance between points (2,3) and (8,7)

   Use the distance formula: sqrt((8-2)^2 + (7-3)^2) = sqrt(6^2 + 4^2) = sqrt(36 + 16) = sqrt(52) ≈ 7.211.

2. Step 2: Check options for closest value

   Compare to ≈7.211: 7 units (closest, diff ≈0.211), 10 units (too high), 6.4 units (diff ≈0.811), 5 units (too low).

3. Step 3: Recalculate carefully

   sqrt(52) ≈ 7.211, so 7 units is closest to actual distance.

4. Final Answer:

   7 units -> Option B

5. Quick Check:

   Distance formula = 7 units [OK]

Hint: Use distance formula sqrt((x2-x1)^2+(y2-y1)^2) [OK]

Common Mistakes:

• Using wrong coordinates order
• Forgetting to square differences
• Choosing approximate values without calculation

4. You used DIMLINEAR but the dimension line is not showing the correct distance. What could be the issue?

medium

A. You selected points that are not aligned horizontally or vertically

B. You used the wrong command; should use DIMANGULAR

C. You forgot to set the scale factor

D. You did not select the dimension style

Solution

1. Step 1: Understand DIMLINEAR behavior

   DIMLINEAR measures horizontal or vertical distance between points. If points are diagonal, it may not show expected distance.

2. Step 2: Identify common mistake

   If points are not aligned horizontally or vertically, the dimension line may appear incorrect or skewed.

3. Final Answer:

   You selected points that are not aligned horizontally or vertically -> Option A

4. Quick Check:

   DIMLINEAR needs horizontal/vertical points [OK]

Hint: DIMLINEAR works best with horizontal or vertical points [OK]

Common Mistakes:

• Using DIMANGULAR instead of DIMLINEAR
• Ignoring scale factor settings
• Not applying dimension style

5. You want to dimension a slanted line between points (1,1) and (4,5) using DIMLINEAR. How do you ensure the dimension line shows the true length of the line?

hard

A. Use DIMLINEAR only between points aligned horizontally

B. Use DIMANGULAR to measure the angle instead

C. Use DIMLINEAR with the rotated option aligned to the line angle

D. Use DIMRADIUS to measure the length

Solution

1. Step 1: Understand limitation of DIMLINEAR

   DIMLINEAR measures horizontal or vertical distances by default, so for slanted lines, it needs rotation.

2. Step 2: Use rotated dimension option

   DIMLINEAR has a rotated option to align the dimension line along the angle of the slanted line, showing true length.

3. Step 3: Confirm other options are incorrect

   DIMANGULAR measures angles, not length; DIMRADIUS measures circle radius; horizontal alignment only works for horizontal lines.

4. Final Answer:

   Use DIMLINEAR with the rotated option aligned to the line angle -> Option C

5. Quick Check:

   Rotated DIMLINEAR shows true length [OK]

Hint: Rotate DIMLINEAR to line angle for true length [OK]

Common Mistakes:

• Using DIMANGULAR instead of linear dimension
• Trying to dimension slanted line without rotation
• Confusing radius with length measurement