Canned cycle cancel (G80) in CNC Programming - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the G80 command do in CNC programming?

G80 cancels any active canned cycle, stopping the machine from repeating the cycle for further holes or cuts.

beginner

Why is it important to use G80 after a canned cycle?

Using G80 ensures the machine stops the canned cycle, preventing unintended repeated operations and potential errors.

intermediate

In a CNC program, where should you place the G80 command?

Place G80 after completing the canned cycle operations, before starting other machining commands.

intermediate

What might happen if you forget to use G80 after a canned cycle?

The machine may continue repeating the canned cycle unintentionally, causing extra holes or cuts and wasting material.

beginner

Example: What does this line do?
G80

This line cancels any active canned cycle, telling the CNC machine to stop repeating the cycle.

What is the purpose of the G80 command in CNC programming?

A Cancel the active canned cycle

B Start a drilling cycle

C Set spindle speed

D Move the tool to home position

G80 cancels any active canned cycle to stop repeated machining operations.

When should you use G80 in your CNC program?

A After completing a canned cycle

B Only during tool changes

C Only at the end of the program

D Before starting a canned cycle

G80 is used after finishing a canned cycle to cancel it.

What could happen if you do NOT use G80 after a canned cycle?

A The machine will stop immediately

B The spindle speed will reset

C The canned cycle will repeat unintentionally

D The tool will change automatically

Without G80, the machine may keep repeating the canned cycle.

Which of these commands cancels a canned cycle?

A G90

B G80

C G81

D G00

G80 is the command to cancel canned cycles.

If you want to stop drilling holes using a canned cycle, which command do you use?

A G81

B G84

C G83

D G80

G80 cancels the drilling canned cycle.

Explain what the G80 command does and why it is important in CNC programming.

Think about what happens after drilling multiple holes.

Describe a situation where forgetting to use G80 could cause problems.

Imagine the machine keeps drilling holes where you don't want them.

Practice

1. What is the main purpose of the G80 command in CNC programming?

easy

A. To start a drilling cycle

B. To set the spindle speed

C. To cancel any active canned cycle

D. To move the tool to the home position

Solution

1. Step 1: Understand what a canned cycle is

   Canned cycles automate repetitive machining tasks like drilling or milling.

2. Step 2: Identify the role of G80

   G80 cancels any active canned cycle to return to normal movement commands.

3. Final Answer:

   To cancel any active canned cycle -> Option C

4. Quick Check:

   G80 cancels canned cycles = B [OK]

Hint: G80 always stops canned cycles safely [OK]

Common Mistakes:

• Thinking G80 starts a cycle
• Confusing G80 with spindle control
• Assuming G80 moves the tool

2. Which of the following is the correct syntax to cancel a canned cycle in CNC code?

easy

A. G81

B. G80

C. M30

D. G90

Solution

1. Step 1: Recall common G-codes for canned cycles

   G81 starts a drilling cycle, G90 sets absolute positioning, M30 ends the program.

2. Step 2: Identify the cancel command

   G80 is the standard code to cancel any active canned cycle.

3. Final Answer:

   G80 -> Option B

4. Quick Check:

   Cancel canned cycle = G80 = A [OK]

Hint: G80 is the cancel code, not G81 or M30 [OK]

Common Mistakes:

• Using G81 instead of G80
• Confusing M30 with cycle cancel
• Mixing positioning codes with cycle cancel

3. Given the CNC program snippet:

G81 X10 Y10 Z-5 R1 F100
G80
G00 X0 Y0

What will the G80 command do here?

medium

A. Cancel the drilling cycle started by G81

B. Move the tool rapidly to X10 Y10

C. Start a drilling cycle at X0 Y0

D. Set feed rate to 80

Solution

1. Step 1: Analyze the G81 command

   G81 starts a drilling canned cycle at X10 Y10 with depth Z-5.

2. Step 2: Understand the effect of G80

   G80 cancels the active canned cycle, stopping the drilling cycle.

3. Final Answer:

   Cancel the drilling cycle started by G81 -> Option A

4. Quick Check:

   G80 cancels G81 cycle = C [OK]

Hint: G80 always cancels previous canned cycles like G81 [OK]

Common Mistakes:

• Thinking G80 starts a cycle
• Confusing G80 with rapid move
• Misreading feed rate as cycle cancel

4. Identify the error in this CNC code snippet:

G81 X20 Y20 Z-10 F150
G00 X0 Y0
G80

medium

A. No error; code is correct

B. G00 cannot be used after G81

C. G80 must be used immediately after G81 to cancel

D. G80 should come before G00 move

Solution

1. Step 1: Understand the order of commands

   G81 starts drilling; G80 cancels it. Moves like G00 should happen after cancel.

2. Step 2: Check the code sequence

   Here, G00 rapid move happens before G80 cancels the cycle, which can cause unexpected behavior.

3. Final Answer:

   G80 should come before G00 move -> Option D

4. Quick Check:

   Cancel cycle before moves = A [OK]

Hint: Always cancel canned cycles before rapid moves [OK]

Common Mistakes:

• Placing G80 after moves
• Assuming G00 cancels cycles
• Ignoring command order importance

5. You have a CNC program that drills multiple holes using G81. After finishing, you want to safely move the tool to a new position without drilling. Which sequence correctly cancels the drilling cycle and moves the tool?

hard

A. G81 X30 Y30 Z-5 F120
G80
G00 X50 Y50

B. G00 X50 Y50
G81 X30 Y30 Z-5 F120
G80

C. G80
G81 X30 Y30 Z-5 F120
G00 X50 Y50

D. G81 X30 Y30 Z-5 F120
G00 X50 Y50
G80

Solution

1. Step 1: Recognize the need to cancel the drilling cycle

   After drilling with G81, G80 must be used to cancel the cycle before moving.

2. Step 2: Check the sequence of commands

   G81 X30 Y30 Z-5 F120 G80 G00 X50 Y50 cancels the cycle with G80 before moving rapidly with G00, which is correct.

3. Final Answer:

   G81 X30 Y30 Z-5 F120 G80 G00 X50 Y50 -> Option A

4. Quick Check:

   Cancel cycle then move = D [OK]

Hint: Cancel cycle (G80) before moving tool (G00) [OK]

Common Mistakes:

• Moving tool before canceling cycle
• Starting new cycle before cancel
• Placing G80 before starting cycle