Invert X/Y/Z Axis
These checkboxes are provided in the event you want to quickly invert a specific axis. It is recommended that you use the “step port invert mask” in the Grbl Settings instead:
Seconds to Wait for Response
A file send will be aborted if Grbl doesn’t respond after this number of seconds. Normally you want this number to be fairly high, over 60 seconds. One specific case where you may want to increase this number is if you have a Shapeoko with meter rails and are doing a slow traverse from one end to the other.
Z-Jog Rate (inches or mm/min)
This is the feed rate used when you click on the up or down buttons to jog the Z axis.
260 mm/min is a good default rate. This field is converted automatically if you change into “inches” mode.
This only affects the Z-jog controls. It does not affect the manual GCode entry.
Use millimeters when sending manual commands (v0.8c+ only)
If you are using an earlier version of Grbl such as v0.8a, leave this checked. Otherwise, if you are running 0.8c or above, you can choose to uncheck this and then all measurements will be in inches.
This includes the LCD displays, the commands given, the jog step sizes, etc.
Note: If a file is specified in inches and you have mm as your mode, Grbl Controller will automatically revert you back to mm after the file is complete. The opposite is also true.
When sending a file, if Z-Rate Limiting is enabled, any commands in the file for the Z axis are assigned a feed rate (or the rate is modified). The assignment occurs at runtime; the actual file is not affected.
If Z-Rate limiting is enabled, this value modifies any Z axis command from the file if the file’s Z rate is greater than the limit. If no rate is specified, this rate will be assigned. If the Z-axis command is a G0, it is converted to a G1.
If a Z rate is specified on the same line with X and/or Y rates, the command is split into the Z command and the X/Y command. The Z command gets the Z rate while the XY gets this XY rate value. Since the feed rate command is modal, if an XY command follows a Z command without a feed rate, this XY rate value is added to that command.
It is recommended that you set this value to the nominal XY feed rate that is found in the file. This can usually be found in the XY command immediately following a Z command containing a feed rate. It is not required, but a lower rate will result in slower completion of the job and a faster rate could be detrimental to the cut.
Use aggressive preload strategy for Grbl
If unchecked, Grbl Controller will wait for a response after each command from the file before sending the next command. If checked, it will send as many commands as fit into the Grbl buffer, then wait for an ok/error response, after which additional commands will be put into the buffer, ensuring that the buffer is always at maximum possible capacity.
Enabling aggressive preload effectively engages Grbl’s “acceleration management” feature to optimize speeds between each command to ensure smooth inter-command transitions. I have observed speed gains of 400-600% with this feature enabled because accelerations and decelerations that take place with normal mode effectively no longer exist in the X-Y axis.
It is highly recommended that you perform a dry run first with this feature enabled to ensure that the speeds are within expected values for the bit, motor speed and material being milled. This is because speeds tend to average higher than with the feature disabled, resulting in greater average load on the bit.
If you were to try to hit the stop button, you will not see immediate response because normally up to 7 or 8 commands are already in the buffer. It is recommended that you use the Close / Reset button if you want to quickly stop operation. It is also recommended that you install limit switches.
Write debugging log to home folder (requires restart)
Enabling this feature will send all status messages and diagnostics to a log file called GrblController.log in the user’s home folder. The file is cleared whenever Grbl Controller is restarted.
The feature does not take effect immediately. If you change this value, you must click OK and then exit Grbl Controller and start it again. This is due to an anomaly with reinitializing Log4Qt.
If you are using a release build, you will see warning and error messages appear in the console (if one is visible, such as in Qt Creator). For debug builds you will see all messages in the console.
Regardless of build, all messages are sent to the log file if the feature is enabled.