Lecture Notes on Canned Cycles in G-Code Programming

Introduction to Canned Cycles

• Presenter: Mark from G Code Cheetah
• Objective: Discuss the use of canned cycles in G-Code programming.

What are Canned Cycles?

• Canned cycles are used to:
  • Speed up programming with G-Code.
  • Simplify code readability by reducing the amount of code.
• Examples of canned cycles include:
  • G81: Drilling cycle
  • G82: Countersink cycle
  • G83: Peck drilling cycle
  • G84: Tapping cycle
  • G85 & G86: Boring cycles
• Canceling Canned Cycles:
  • Canned cycles need to be canceled with G80 after completion.

Multiple Repetitive Cycles

• Used more on lathes than mills.
• Examples include:
  • G70: Finishing cycle
  • G71: Roughing cycle
  • G72: Facing cycle
  • G74: Face grooving cycle
  • G76: Screw cutting cycle
• No need to cancel these cycles with G80.

Canned Cycles vs. CAD/CAM Output

• Canned cycles condense code compared to CAD/CAM outputs which may have pages of code.
• Modern CAD/CAM software increasingly incorporates cycles, reducing code complexity.

Example of G81 Drilling Cycle

• Basic Structure:
  • Start with G81 and end with G80.
• Cycle Line Information:
  • Z-depth: Default depth; can be overridden on a per-hole basis.
  • R value: Retract value; sets tool retraction position.
  • Feed Rate: Specifies material removal speed.
• Programming Flexibility:
  • Position before cycle or within cycle using X and Y coordinates.
• Incremental vs. Absolute Movements:
  • Incremental moves are relative to the last known position.
  • Some machines auto-switch to incremental in G81 mode, others require manual switch with G91.
  • Switch back to absolute with G90.

Other Canned Cycles

• G82 (Countersink/Spot Drill):
  • Use P value to add dwell time (e.g., P500 for half a second).
• G83 (Peck Drilling):
  • Use Q value to set peck depth (e.g., Q3 for 3mm cuts).
• G84 (Tapping):
  • Alter feed rate to match the pitch of the tap/thread.
  • Switches machine to feed per revolution.

Conclusion

• Canned cycles offer a simplified, efficient approach to G-Code programming.
• Different cycles provide different functionalities tailored to specific machining tasks.
• Understanding machine-specific configurations is crucial for effective cycle programming.