G-code program structure in CNC Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start a G-code program with the correct program number.

CNC Programming

O[1] (Start of program)

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

A1001

BG01

CM30

DG90

Attempts:

3 left

💡 Hint

Common Mistakes

Using G-codes or M-codes instead of a program number.

Omitting the program number after 'O'.

The program number starts with 'O' followed by a number, like 1001.

2fill in blank

medium

Complete the code to set the machine to absolute positioning mode.

CNC Programming

[1] (Set absolute positioning)

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

AG91

BG90

CM03

DG00

Attempts:

3 left

💡 Hint

Common Mistakes

Using G91 which is relative positioning.

Confusing spindle start codes with positioning codes.

G90 sets the machine to absolute positioning mode.

3fill in blank

hard

Fix the error in the code to properly end the program.

CNC Programming

M[1] (End of program)

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

A00

B03

C30

D05

Attempts:

3 left

💡 Hint

Common Mistakes

Using M00 which pauses but does not end the program.

Using spindle start codes like M03 instead of end codes.

M30 is the standard code to end and rewind the program.

4fill in blank

hard

Fill both blanks to move the tool rapidly to X=50 and Y=25.

CNC Programming

G[1] X[2] Y25

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

A00

B01

C50

D25

Attempts:

3 left

💡 Hint

Common Mistakes

Using G01 which is linear feed move instead of rapid.

Mixing up coordinate values for X and Y.

G00 is rapid move, and X coordinate is 50.

5fill in blank

hard

Fill all three blanks to set spindle speed to 1200 RPM and start clockwise rotation.

CNC Programming

S[1] M[2]

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

AM03

B1200

C30

DM05

Attempts:

3 left

💡 Hint

Common Mistakes

Using M05 which stops spindle instead of starting it.

Confusing spindle speed with feed rate codes.

S1200 sets spindle speed to 1200 RPM, M03 starts spindle clockwise.

Practice

1. What is the correct way to start a G-code program?

easy

A. Write G90 as the first line

B. Start with the command M30

C. Use G01 to start the program

D. Begin with a program number like O1000

Solution

1. Step 1: Identify the program start syntax

   G-code programs start with a program number, usually written as O1000 or similar.

2. Step 2: Understand the role of other commands

   M30 ends the program, G01 and G90 are motion and positioning commands, not start markers.

3. Final Answer:

   Begin with a program number like O1000 -> Option D

4. Quick Check:

   Program start = O1000 [OK]

Hint: Program always starts with O-number like O1000 [OK]

Common Mistakes:

• Confusing M30 as start instead of end
• Using motion commands as start
• Skipping program number line

2. Which of the following lines correctly ends a G-code program?

easy

A. G00 X0 Y0

B. O1000

C. M30

D. G90

Solution

1. Step 1: Identify the program end command

   The command M30 is used to stop and end a G-code program.

2. Step 2: Differentiate from other commands

   G00 moves the tool, G90 sets positioning mode, and O1000 is a program number, not an end command.

3. Final Answer:

   M30 -> Option C

4. Quick Check:

   Program end = M30 [OK]

Hint: Program ends with M30 command [OK]

Common Mistakes:

• Using motion commands as program end
• Confusing program number with end command
• Omitting M30 at program end

3. Given the following G-code snippet, what is the tool's final position?

O1000
G90
G00 X10 Y5
G01 X20 Y15 F100
M30

medium

A. X20 Y15

B. X10 Y5

C. X0 Y0

D. X100 Y100

Solution

1. Step 1: Trace the tool movements

   G00 X10 Y5 moves the tool rapidly to X=10, Y=5. Then G01 X20 Y15 F100 moves it linearly to X=20, Y=15.

2. Step 2: Identify final position before program end

   The last position command is G01 X20 Y15, so the tool ends at X=20, Y=15.

3. Final Answer:

   X20 Y15 -> Option A

4. Quick Check:

   Last move = X20 Y15 [OK]

Hint: Final position is last coordinate command before M30 [OK]

Common Mistakes:

• Confusing rapid move (G00) as final position
• Ignoring linear move (G01)
• Assuming start position is final

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

O2000
G01 X10 Y10
G90
M30

medium

A. G90 should come before G01 for positioning mode

B. M30 is used incorrectly

C. Missing program start number

D. No error, program is correct

Solution

1. Step 1: Check command order for positioning

   G90 sets absolute positioning and should be set before any move commands like G01.

2. Step 2: Analyze the given order

   The program moves with G01 before setting G90, which can cause unexpected positioning behavior.

3. Final Answer:

   G90 should come before G01 for positioning mode -> Option A

4. Quick Check:

   Set positioning mode before moves [OK]

Hint: Set G90 before moves to avoid positioning errors [OK]

Common Mistakes:

• Placing G90 after move commands
• Ignoring command order importance
• Assuming M30 ends program incorrectly

5. You want to write a G-code program that sets absolute positioning, moves the tool to X=50 Y=50 at feed rate 200, then ends the program. Which is the correct structure?

hard

A. O3000
G01 X50 Y50 F200
G90
M30

B. O3000
G90
G01 X50 Y50 F200
M30

C. G90
O3000
G01 X50 Y50 F200
M30

D. O3000
M30
G90
G01 X50 Y50 F200

Solution

1. Step 1: Confirm program start and positioning

   The program must start with a program number O3000 and set absolute positioning G90 before moves.

2. Step 2: Check move command and program end

   G01 X50 Y50 F200 moves the tool at feed rate 200, and M30 ends the program properly.

3. Final Answer:

   O3000 G90 G01 X50 Y50 F200 M30 -> Option B

4. Quick Check:

   Start with O-number, set G90, move, then M30 [OK]

Hint: Start with O-number, set G90, move, then M30 to end [OK]

Common Mistakes:

• Placing M30 before moves
• Setting G90 after moves
• Starting without program number