GRBL is the CNC controller firmware most widely used by DIY enthusiasts and hobbyists in the CNC machining world. It is free, easy to set up, and can even run on an Arduino board.
However, it requires you to have a computer to control most GRBL-based controllers. But there are some controllers that allow you to run your CNC without a computer.
In this article, I have reviewed some of the best GRBL offline CNC controllers available in the market. Most of these offline controllers allow you to run G-code off a memory stick.
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Best Offline GRBL Controllers for CNC
I have evaluated some of the best offline GRBL CNC controllers for their ease of use, build quality, capabilities, and support.
1. OpenBuilds INTERFACE CNC Touch
INTERFACE CNC Touch is a product by OpenBuilds, it’s the best quality controller on this list and is used by a lot of people.
The interface comes with a surge suppressor board, a 2.5m connection cable, a USB drive, and a USB-C cable.
It’s a human-machine interface that puts machine control directly into your hands. You can jog, zero, home, and run your CNC machine all from the Interface CNC Touch.
CNC Touch can work in standalone mode by accepting G-code directly through a FAT32 USB flash drive.
It also can be interfaced with any controller flashed with GRBL 1.1 firmware (GRBL offline controller firmware) that has RX/TX/GND/5V pins. Some may require you to make custom cabling for it to operate.
The flash drive only accepts FAT32 formatted drives which can also be used to update the firmware. The file names in the drive are shown in 8.3 formats and it doesn’t support long filenames.
It uses a 32-bit 250MHz Xtensa dual-core microprocessor with 520Kb of SRAM. It has a USB-C port that can be used to connect to a computer and update the firmware.
CNC Touch uses a high-contrast Thin-Film-Transistor (TFT) LCD to clearly show the control interface. Its interface display has a status bar that shows the GRBL status.
It has LED-lit capacitative touch buttons for you to interact with the machine, it also uses a beeper, and a vibration motor to give feedback to the user.
The status LEDs on its front panel show the status of USB, AUX, drive, and WiFi through green/red color as and when they and receiving/transmitting data.
Interface CNC Touch has a reset button for you to use, this restarts the firmware and in most cases solves most of its working issues.
All these parts are enclosed in a high-end metal enclosure. The enclosure is also made to be mounted with the OpenBuilds Interface Mounting Kit.
2. Genmitsu GRBL Offline Controller V2
Genmitsu has recently released the Genmitsu V2 offline controller, it’s an upgraded version of one of their previous offline controller.
It’s compatible with Genmitsu CNC Router 3018-PROVer, Laser Engraving Machine LE5040, Jinsoku LE-1620, Jinsoku LC-60A, and other generic 3018 CNC routers that run on a GRBL firmware.
You won’t be able to make use of this controller when a computer is already connected to the CNC machine. To take over the machine control, you’ll have to disconnect the computer and then plug in Genmitsu offline controller.
The major upgrade for the Offline V2 (Version 2) controller is, it can handle more file types than its earlier version.
Make sure your file names are not too long, it won’t display file names with more than 19 characters (including the file extension).
You should convert your G-codes to standard format using a CR/LF sequence to separate each line for the controller to run.
Some software only uses a single line feed character to separate the G-code lines, avoiding such programs is the best option. Else you’ll have to go in and edit it all by yourself.
With the offline controller, you’ll get an SD card and a 10-pin ISP cable which is used to interface with the CNC machine.
The SD card comes loaded with two separate .txt files having commands for the controller to interface with the spindle and laser. This should never be deleted as they are essential for its operation.
You can easily load your G-code to the SD card. Once it’s loaded, you can install the SD card on the controller and choose the file to run.
While running a G-code, you’ll also be able to see the name of the file you are running, its status, and the work progress in percentage.
You can pause and resume your work through the offline controller by pressing the “enter” button. When paused, it stops the online controller from sending G-codes to the CNC machine.
Genmitsu v2 GRBL offline controller has a 1.8″ display through which you’ll be able to see and guide through its menu.
It has 6 buttons to jog the X, Y, and Z-axis just like any other offline controller out there. To guide through the controller you have separate “select” and “enter” buttons.
You can zero and home all three axes directly from the controller. To change the steps, you can use the step button to adjust how many axes movement it achieves in one button click.
3. Rattm Motor 3 Axis CNC Offline Controller
Rattm Motor has released the 3-axis GRBL CNC controller that helps you control your CNC router without a computer.
The offline controller comes with a 10P ISP cable and an SD card. The 10P cable is used to interface the controller with the CNC machine.
It supports SD and TF cards through which you can input 3-axis G-codes for the controller to run.
If needed you can connect to the computer using its micro USB cable to run files directly from it. It supports .nc, .tex, .tap file formats.
The controller is enclosed in an injection-molded plastic case. Though not a rigid option to have, it gives you an economical controller.
It has a set of push-button switches, the six black switches are to control X, Y, and Z axes. Each axis control has two buttons to control +/- axis movements.
The two yellow buttons with the Y+ and Y- black buttons are used to navigate to and fro through the controller’s user interface which is shown through a small LCD.
While you press and hold the “Ok/Spindle” button at the center of XY controls, you can use Z+ and Z- buttons to increase or decrease the speed of the spindle. It can also be used with a motor or a laser.
Rattm Motor 3-axis CNC offline controller is quite easy to operate and is a pretty beginner-friendly product.
- The injection molded case is beautiful and formal; the integral button and the key cap are not easy to fall off.
- Support SD card and TF card at the same time, standard capacity 1G.
4. LEKN G-Sender Offline Controller
LEKN GRBL CNC offline controller (smart controller) comes with an SD card, 5P-cable, and the 3-axis G-Sender module (LCD control board). Unlike other controllers we discussed above, this one comes with only two switches.
The rotary encoder switch is the major feature, it is used to guide through the controller menu and perform different operations.
You can rotate the encoder switch left and right to move to different menu options. For choosing an option you’ll have to press the same switch. It’s just like how a scroll button on a computer mouse would work.
Another button you have is the “stop” button, which uses a 4-pin push button that can be pressed to halt the machine’s operation.
You can easily connect the smart controller to the GRBL controller board using the 5V/GND/TX/RX ports. It can be wired using the 5P cable that you get with the offline smart controller.
Each wire in the 5P cable is color-coded for the ease of connecting it with the controller board. It makes DIY CNC machinists’ jobs easy.
Using the smart controller you can control all three axes and you can choose step sizes of 0.1mm, 1mm, and 10mm.
By enabling the GRBL homing function you can home your CNC from its control menu.
The controller also has options like spindle speed, zero position, set origin, GRBl mode, etc.
From the settings menu, you can access the baud rate, buzzer, and memory menu.
The buzzer is by default active and will make a sound with each keypress, it can be turned off from the settings menu.
Files stored in the SD card can be accessed from the card menu on the main screen of the LCD menu. It shows you the files on the SD card but doesn’t show those that are saved inside folders.
This smart controller is simple, you can learn its workflow by using it for a couple of sample projects.
If you are not comfortable working with the open circuitry board, you can get the protective bezel kit for the LEKN G-Sender or you can make one by yourself.
5. Grbl Controller
“Grbl Controller” developed by Silicon Circuits is an Android mobile app used to control CNC machines running on GRBL 1.1 firmware. It’s compact and at the same time has some advanced features.
Though not technically an offline controller, I’m including it in this article because it’s used by a lot of people for controlling their CNC remotely and I thought it may be an option some readers might find interesting.
Grbl Controller application has all the features of a standard GRBL CNC offline controller and helps you stream G-code to your CNC machine using a smartphone or a tablet running on Android KitKat or above.
You can interface your CNC machine with the Grbl Control application via Bluetooth or OTG.
If you are planning to control via Bluetooth, make sure the baud rate set in the GRBL firmware matches the Bluetooth module you are using. The most common baud rate used by Bluetooth manufacturers is 9600.
You can have a look at their Bluetooth setup guide to properly set it up.
I suggest you go with the OTG connection as it’s simple and anyone can do it right on the first go. All you have to do is connect the CNC and your android phone with a USB OTG cable.
Once you connect, it’ll show a connection prompt if the firmware matches. If not, you’ll have to update the serial firmware/bootloader.
When you open the application, the app-front panel shows the machine state, machine position, work position, axis labels, G-code parser state, buffer state, and the current feed rate.
All these small details help you keep a watch on the machine’s performance and status.
You can select and load the G-code files by using the stock file manager. It supports .tap, .gcode, .nc, and .ngc file formats.
From its jogging control panel, you can jog, home, and zero your CNC machine. Jogging step size and feed rates can also be adjusted from here.
You can’t pause and run the job using the standard version of the application, for that you need to use “Grbl Control +” which is a paid application.
The Grbl Controller + also has many features like job history, in-app documentation, jog pad rotation, haptic feedback, additional A, and B axes support, and much more.
Grbl Controller from Silicon Circuits brings a great deal of flexibility in controlling your CNC machine if you have an Android phone to put into use.
Frequently Asked Questions (FAQs)
What does an offline CNC controller do?
Offline controllers can take over and control the motion of your CNC machine without the need of using a computer. It’s useful when you are running long and repeating jobs as you don’t have to keep your computer busy and awake. It’ll be having memory card slots through which you can load G-codes necessary to run the job and you can also jog, home, and probe your CNC machine directly from the controller.
What does GRBL run on?
GRBL software is widely run on Arduino boards which use an ATmega328 microcontroller. It also runs on a variety of microcontrollers. It is used to achieve machine movement in many different applications and is mainly used in operating CNC machines.
Is GRBL good for CNC?
GRBL is a good option for CNC as it is open-source software that has become an industry standard for 3-axis CNC motion control. It’s supported by many CNC software like MasterCAM and Fusion 360 which can run in combination with GRBL. It also doesn’t need a parallel port and works using a USB connection allowing you to run your CNC with a computer without parallel ports.
