Why G-code is the language of CNC machines in CNC Programming - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to move the CNC machine to the origin point.

CNC Programming

G0 X[1] Y0 Z0

Drag options to blanks, or click blank then click option'

A0

B-10

C100

D10

Attempts:

3 left

💡 Hint

Common Mistakes

Using a non-zero value moves the machine away from the origin.

Confusing G0 with G1 which is for controlled feed movement.

G0 command moves the machine quickly to the specified coordinates. To move to the origin, X must be 0.

2fill in blank

medium

Complete the code to set the feed rate to 150 mm/min.

CNC Programming

F[1]

Drag options to blanks, or click blank then click option'

A200

B50

C150

D100

Attempts:

3 left

💡 Hint

Common Mistakes

Using a feed rate too high or too low for the material.

Confusing feed rate with spindle speed.

F command sets the feed rate. To set it to 150 mm/min, use F150.

3fill in blank

hard

Fix the error in the code to perform a linear cut to X=50, Y=25 at feed rate 100.

CNC Programming

G1 X[1] Y25 F100

Drag options to blanks, or click blank then click option'

A50

B25

C75

D100

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong X coordinate causes the tool to cut in the wrong place.

Omitting feed rate or using wrong command.

The code moves linearly to X=50, Y=25 at feed rate 100. X must be 50 to match the instruction.

4fill in blank

hard

Fill both blanks to define a clockwise circular move with radius 10 starting at current position.

CNC Programming

G2 I[1] J[2]

Drag options to blanks, or click blank then click option'

A10

B-10

C0

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Using negative radius when positive is needed.

Swapping I and J values.

G2 is clockwise arc move. I and J define the center offset from start. Radius 10 on X (I=10), no offset on Y (J=0).

5fill in blank

hard

Fill all three blanks to create a dictionary that maps axis names to their zero positions.

CNC Programming

{'X': [1], 'Y': [2], 'Z': [3]

Drag options to blanks, or click blank then click option'

A0

B1

C-1

DNone

Attempts:

3 left

💡 Hint

Common Mistakes

Using different values for axes when zero is expected.

Using None or negative values incorrectly.

The zero position for all axes is 0, so all values should be 0.

Practice

1. Why is G-code considered the language of CNC machines?

easy

A. Because it provides step-by-step instructions for machine movements

B. Because it is a programming language for web development

C. Because it controls the color of the machine

D. Because it is used to write emails

Solution

1. Step 1: Understand the role of G-code in CNC machines

   G-code gives clear instructions on how the machine should move and operate.

2. Step 2: Compare options to the role of G-code

   Only Because it provides step-by-step instructions for machine movements correctly describes G-code as step-by-step machine instructions.

3. Final Answer:

   Because it provides step-by-step instructions for machine movements -> Option A

4. Quick Check:

   G-code = step-by-step instructions [OK]

Hint: G-code tells machines what to do step-by-step [OK]

Common Mistakes:

• Confusing G-code with general programming languages
• Thinking G-code controls colors or emails
• Assuming G-code is for software development

2. Which of the following is a correct G-code command to move the tool in a straight line?

easy

A. T01 M06

B. M03 S1000

C. G28

D. G01 X10 Y20

Solution

1. Step 1: Identify the command for linear movement

   G01 is the G-code command for linear interpolation (straight line move).

2. Step 2: Check other commands for their functions

   M03 S1000 starts the spindle, G28 moves to home, T01 M06 changes tool; none move in a straight line.

3. Final Answer:

   G01 X10 Y20 -> Option D

4. Quick Check:

   G01 = straight line move [OK]

Hint: G01 means move straight to coordinates [OK]

Common Mistakes:

• Confusing spindle commands with movement commands
• Using tool change commands as movement
• Mixing up G28 (home) with G01 (linear move)

3. What will be the result of this G-code snippet?

G00 X0 Y0
G01 X10 Y0 F100
G01 X10 Y10 F100

medium

A. The tool moves slowly to (0,0), then moves quickly to (10,0), then stops

B. The tool changes tools twice

C. The tool moves quickly to (0,0), then cuts a line to (10,0), then cuts a line to (10,10)

D. The machine will produce an error

Solution

1. Step 1: Analyze each G-code line

   G00 moves fast to (0,0). G01 moves linearly to (10,0) at feed rate 100. Next G01 moves linearly to (10,10) at feed rate 100.

2. Step 2: Understand the overall tool path

   The tool first quickly moves to start, then cuts two straight lines forming an L shape.

3. Final Answer:

   The tool moves quickly to (0,0), then cuts a line to (10,0), then cuts a line to (10,10) -> Option C

4. Quick Check:

   G00 = fast move, G01 = cut move [OK]

Hint: G00 = fast move, G01 = cutting move [OK]

Common Mistakes:

• Thinking G00 is a cutting move
• Assuming tool changes happen here
• Believing the code causes errors

4. Identify the error in this G-code snippet:

G01 X20 Y20 F150
G02 X30 Y30 R10

medium

A. Missing feed rate (F) in the second line

B. G02 cannot be used with radius (R)

C. Coordinates X30 Y30 are invalid

D. G01 should be G00 for cutting

Solution

1. Step 1: Check feed rate usage in G-code lines

   First line has feed rate F150, second line with G02 (arc move) lacks feed rate.

2. Step 2: Understand feed rate necessity for cutting moves

   Feed rate is required for cutting moves like G02 to control speed; missing F causes error.

3. Final Answer:

   Missing feed rate (F) in the second line -> Option A

4. Quick Check:

   Cutting moves need feed rate F [OK]

Hint: Cutting moves must include feed rate F [OK]

Common Mistakes:

• Thinking G02 can't use radius R
• Assuming coordinates are invalid
• Confusing G00 and G01 commands

5. You want to automate a CNC machine to cut a square of 20mm sides starting at (0,0). Which G-code sequence correctly achieves this?

hard

A. G01 X0 Y0 F100
G02 X20 Y0 R20
G02 X20 Y20 R20
G02 X0 Y20 R20
G02 X0 Y0 R20

B. G00 X0 Y0
G01 X20 Y0 F100
G01 X20 Y20 F100
G01 X0 Y20 F100
G01 X0 Y0 F100

C. G00 X0 Y0
M03 S500
G01 X10 Y10 F50
G01 X20 Y20 F50

D. G28 X0 Y0
G01 X20 Y20 F100
G01 X0 Y0 F100

Solution

1. Step 1: Understand the task to cut a square starting at (0,0)

   The tool must move to start, then cut four straight sides of 20mm each.

2. Step 2: Analyze each option for correct moves and feed rates

   G00 X0 Y0 G01 X20 Y0 F100 G01 X20 Y20 F100 G01 X0 Y20 F100 G01 X0 Y0 F100 moves fast to start (G00), then cuts four straight lines with G01 and feed rate F100, forming a square.

3. Step 3: Check other options for errors

   G01 X0 Y0 F100 G02 X20 Y0 R20 G02 X20 Y20 R20 G02 X0 Y20 R20 G02 X0 Y0 R20 uses arcs (G02) which do not form a square. G00 X0 Y0 M03 S500 G01 X10 Y10 F50 G01 X20 Y20 F50 cuts only partial lines and starts spindle without full square. G28 X0 Y0 G01 X20 Y20 F100 G01 X0 Y0 F100 moves home then cuts diagonally, not square sides.

4. Final Answer:

   G00 X0 Y0 G01 X20 Y0 F100 G01 X20 Y20 F100 G01 X0 Y20 F100 G01 X0 Y0 F100 -> Option B

5. Quick Check:

   Square cut = straight lines with G01 [OK]

Hint: Cut squares with four G01 lines and feed rates [OK]

Common Mistakes:

• Using arcs instead of straight lines for squares
• Missing feed rates on cutting moves
• Not returning to start point