Grbl Controller Options

Grbl Controller 3.2 Options

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:

Grbl Controller - Grbl Settings

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.

Z-Rate Limiting

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.

Z-Rate Limit

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.

XY Rate

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.

11 thoughts on “Grbl Controller Options

  1. After I changed the seconds to wait for response on the controller the grbl lags and hangs. But when I use the serial monitor from the arduino there is no lag and no hang ups. I tried uninstalling the controller and then when I reinstall the same number of seconds appears. The uninstall removes the directory. Is there a settings file that is stored elsewhere that I can wipe? I’m using Windows 7.

  2. how do i increase the speed … i have tried different feed and seek rates and there is no change… speed changes by ch????anging steps/mm… but changing that changes the distance covered….

  3. how do i increase the speed???? … i have tried different feed and seek rates and there is no change… speed changes by changing steps/mm… but changing that changes the distance covered….

    • First off, you must properly set the steps/mm. Then, you can set the feed/seek rates in grbl with the $(value) commands, but that will only work for manual control. If you are running a file, most programs generate gcode with the feed rates overriden from the default. If manually controlling, the F command added to another command can be used to adjust the feed rate. I believe it will keep that rate until changed. I am interested in hearing what you discover – I would like to help you solve the problem.

  4. I received this error message after installing two limit switches on the z-axis and setting $16=1. (Arduino Uno/gShield 11 and 14)
    ALARM: Hard Limit. MPos?
    Is there any remedy for this situation? Thank you!

    • I haven’t worked with limit switches yet. The alarm should be resetable by clicking on the Advanced tab on the main window and clicking Unlock Grbl. If that doesn’t work, try Soft Reset Grbl followed by Unlock Grbl.

      Another possibility is that the machine and work coordinates need to be reset to 0 before the limit switches engage, but I would have to test. This can be done by closing and opening the port.

  5. What are the keyboard shortcuts for the jogging/axis control buttons?
    ….or are there any?

    If not, could this be easily added? :) It would definitely make adding a home-brew pendant a lot easier (or just a keyboard)

  6. Grbl settings in which each function is, what should I do to decrease the speed of each axis and z independent? Thank you.

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