G-Code & M-Code Programming Flashcards

What G-code activates the peck drilling canned cycle?

Answer: G83

G83 is the deep hole peck drilling cycle that retracts the drill fully to the R-plane between each peck to clear chips.

Which address letter is used to call a tool offset register when programming tool length compensation?

Answer: H

The H-word specifies which tool length offset register number is applied when G43 or G44 is active.

What is the function of M30 in a CNC program?

Answer: End program and return to start

M30 ends the program, rewinds to the beginning, and resets all modal states, readying the machine for the next run.

In a right-hand coordinate system on a vertical machining center, which direction is positive Z?

Answer: Away from the table (spindle retracting upward)

Positive Z moves the spindle away from the workpiece (upward on a VMC), following the right-hand rule.

What does the 'R' value represent in a G81 drilling canned cycle?

Answer: The retract plane height above the work surface

In canned cycles, R specifies the retract (reference) plane — the Z-height where the drill stops before the next hole.

Which G-code establishes a fixed cycle for tapping?

Answer: G84

G84 is the right-hand tapping canned cycle, which reverses the spindle at the bottom of the hole to retract the tap.

What is the effect of programming 'G00 Z0.1' before a drilling canned cycle?

Answer: Positions the tool at the Z rapid approach height above the part

A G00 Z move before a canned cycle rapid-positions the tool to the approach height (clearance plane) above the workpiece.