# LinuxCNC G74 Left-hand Tapping Cycle with Dwell

Instructions · `G74` · verification: source checked

G74 is a LinuxCNC G-code cycle for left-hand tapping with a floating chuck. It moves the Z axis at the programmed feed rate to the Z position, stops the selected spindle, starts clockwise spindle rotation, dwells for P seconds, and feeds back to clear Z. The document states that G74 does not use synchronized motion.

## Specification

| Property | Value |
|---|---|
| Language | gcode |
| Code | G74 |
| Syntax | G74 (X- Y- Z-) or (U- V- W-) R- L- P- $- F- |
| Dialect | LinuxCNC |

### Parameters

| Name | Description |
|---|---|
| X |  |
| Y |  |
| Z |  |
| U |  |
| V |  |
| W |  |
| R | Retract position along the Z axis. |
| L | Used in incremental mode; number of times to repeat the cycle. See G81 for examples. |
| P | Dwell time (seconds). |
| $ | Selected spindle. |
| F | Feed rate (spindle speed multiplied by distance traveled per revolution (thread pitch)). |

## Safety

- Warning: G74 does not use synchronized motion.
- Feed and speed overrides are disabled during the G74 cycle and restored after it finishes.

## Study notes

- The feed rate F is spindle speed multiplied by distance per revolution (thread pitch); the document gives S100 with 1.25 mm per revolution as F125.
- The L word is used in incremental mode to repeat the cycle; the document refers to G81 for examples.
- The G74 cycle uses preliminary and in-between motion from the canned cycle motion section.

## Sources

1. [G-Codes](https://linuxcnc.org/docs/html/gcode/g-code.html#gcode:g74) (accessed 2026-10-26)

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Source page: https://machineschema.com/instruction/gcode-g74  
JSON: https://machineschema.com/instruction/gcode-g74.json  
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite Machine Schema and the original sources.