Best GRBL Controllers

GRBL is the most widely used CNC controller among hobbyists and DIYers. Beginner CNCs like Shapeoko, Sainsmart, and OpenBuilds all use GRBL CNC controllers, as well as entry-level lasers since GRBL is also compatible with Lightburn.

However, making the wrong selection could lead to numerous issues.

You might find your Z-axis rendered immovable if your GRBL controller was designed specifically for lasers – or worse, you risk frying your power supply or new controller board!

So, how do you avoid these pitfalls? By choosing one of the best CNC GRBL controllers on the market, which I’ve curated in this article to help you make the right choice.

The RATTMMOTOR CNC 3018 PRO is my top choice for budget-conscious beginners seeking a CNC GRBL Controller. It’s great value for money – perfectly capable of good performance on hobbyist low-powered spindles and lasers.

Meanwhile, the SainSmart Genmitsu CNC Controller Board caters to more powerful stepper motors and spindles, while the premium BlackBox Motion Control System stands out with superior features and advanced cooling capabilities (and a steeper price tag!).

09/29/2023 02:56 pm GMT

Buying a GRBL controller saves you from electronic hassles and flashing firmware, and since the firmware is open source, GRBL controllers are very affordable.

In this guide, I’ll share my hands-on experience with the best GRBL controllers I’ve tested, comparing them across important features – like spindle and access support, power supply, and operating system compatibility – so you can make the right choice for your device.

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Best GRBL Controller Boards

You can use any GRBL control software to control these boards. I recommend UGS for CNCs, and LaserGRBL for lasers. However, there are other good options too, and I’ve also written about them in my guide to the best GRBL control software.

Best Budget CNC Controller: Rattm Motor/CNCTOPBAOS/Sainsmart

Rattm Motor/CNC TOPBAOS/SainSmart


Supports spindle and laser.

Air fan.

Wide spindle speed range.

Supports offline controller.

ABS protective shell.


Soldered drivers.

Direct switching (low-powered) 24v spindles only.

Most people know Rattm Motor GRBL controller as one of the lowest price GRBL boards on the market. But we’re not talking about that board here – we’re discussing the Sainsmart 3018 controller.

I’m almost certain that Sainsmart 3018’s controller is made by Rattm Motor (although Sainsmart only says that the country of origin is China). CNCTOPBAOS’s GRBL controller is the same rebranded board. These boards are probably the same.

Although this GRBL controller board is not perfect, it gets many things right. It has a built-in fan to cool down the stepper motor drivers, so you can draw a little more current from this GRBL board versus worse-designed boards with similar drivers. However, avoid exceeding 1.5-1.6A per stepper motor.

Another cool thing is that you can also buy an offline controller to jog the CNC (and send some commands) without a computer. You can check out the offline controller here. Since this GRBL controller is compatible with Sainsmart 3018, Sainsmart’s offline controllers also work with this board.

Another plus is the enhanced GRBL controller’s spindle PWM generation. While some GRBL controllers can only speed a spindle up to about 10000 RPM, this GRBL controller board can go to higher speeds. 

However, it can only switch low-powered spindles up to 240W. For example, you can’t use the 300W 20000RPM spindle that Sainsmart users buy from the company.

The design is also good. The board has a power button, and an outer glass case to protect the GRBL controller. Also, 6 limit switch ports are a must for suitable CNC GRBL controllers.

On the downside, the stepper motor drivers are soldered to the GRBL controller board, so you may have to replace the whole board if you burn one of them. Also, this GRBL controller can only switch spindles weaker than 240W directly. 

Finally, this GRBL controller board runs on 24V only, so you can’t vary the supply voltage.

Best Budget Pick
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09/29/2023 02:36 pm GMT
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09/29/2023 02:51 pm GMT
SainSmart Genmitsu 3018-PROVer Desktop CNC Router Machine with GRBL Offline Control

It's cheap, and not super powerful, but with a few upgrades it can cut into thin aluminum.

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09/29/2023 03:01 pm GMT

Best Electronics at a Budget: Sainsmart Genmitsu CNC Controller Board

SainSmart Genmitsu CNC Controller Board


Anti-interference electronics.


Switches more powerful spindles.

Full spindle speed range.

High stepper motor current.


Poor documentation: can cause problems for DIYers.

No air fan.

Possible problems adjusting stepper motor current (but we cannot verify this information).

This is Sainsmart’s controller board for 3018 PROver and 3018 MX3 CNCs. Sainsmart is really hush-hush about this board’s electronics and capabilities, but I have uncovered some information about it. But don’t take this info as fact, or any kind of Sainsmart formal statement!

This is a GRBL CNC controller that’s compatible with both CNCs and lasers. This board is slightly more expensive than the GRBL controller board mentioned above. 

Sainsmart says the board has 8GB of memory, and is compatible with Genmitsu’s Upgraded Offline Controller V2. The CNC controller board also has optocouplers on inputs for isolation, giving it a robust anti-interference layer.

This Genmitsu GRBL controller board supports emergency stop buttons and limit switches. It also supports setting the tool to Z=0, so you can set the zero to the material’s surface or the clearance plane if you want.

Now, let’s see the informal info:

We know that this board has enhanced electronics. Users have reported that Sainsmart gives them this board if they choose a 300W 20000 RPM spindle, proving the board can switch more powerful spindles above 240W. It also controls the spindle’s full speed range.

Another user reports that this board uses tb67s109afng stepper motor drivers. This is a huge improvement over all the budget GRBL controllers, as this driver can run much more powerful stepper motors. 

Based on this info, you can provide NEMA 23 stepper motors with 3A using this GRBL controller. However, the same user reportedly had problems adjusting the stepper motor current. So, this board is adjusted for Sainsmart machines and doesn’t care about other users. 

We can also see this in the lack of an air fan, because the heat sink is enough for Sainsmart machines. But, if you’re a DIYer using this board for a more powerful machine, you may need an air fan.

On the downside, Sainsmart’s secrecy about the Genmitsu controller has resulted in poor documentation. This can cause DIYers to have to test parts of the electronics on their own.

Best Electronics
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09/29/2023 02:56 pm GMT

Best High-End GRBL Controller: OpenBuilds BlackBox Motion Control

OpenBuilds BlackBox Motion Control


Modular design

High stepper current.

Powerful spindle switching.

Full spindle speed control.

Powerful pump and coolant control.

Air fan.

Power input polarity protection

Flexible input range.



Expensive GRBL board.

BlackBox Motion Control is the best GRBL controller board with unique capabilities. However, it’s also the priciest GRBL controller I’ve come across: it costs $219.99

Firstly, BlackBox Motion control can power stronger stepper motors. While other GRBL controllers claim to deliver 2A per stepper motor, it’s best to stay about 1.5A to avoid damaging them.

However, this BlackBox CNC GRBL controller can generate 3A per stepper motor. So, you can even control NEMA 23 or NEMA 34 motors that require up to 4A of peak current.

It also has a configurable relay that you can adjust for various spindles or lasers. Plus, it offers additional relays for controlling other motors like pumps and coolants (up to 120W motors).

It has an analog output for sending speed signals to spindle VFDs. It covers the whole voltage range required for all spindle speeds (0 to 20000 RPM).

There are two large heat sinks and a fan. Another great advantage is its excellent modular design: it’s ease to disassemble, including the casing, outer shell, connectors, and fan.

Even its end-stops inputs are compatible with a range of voltages (5-24V). So, almost all end-stop inputs are compatible with BlackBox Motion. Additionally, BlackBox Motion Control supports probes for all axes (XYZ).

What happens if you mistakenly connect the power supply to the BlackBox Motion with the wrong polarity? While many GRBL controllers will burn, this expensive board won’t – it has polarity protection and LED indicators to tell you about the correct polarity input.

In fact, BlackBox Motion has LEDs to show the spindle state, stepper motor, coolant, and laser. It even has RGB LEDs to brighten the logo.

Best High-end GRBL Controller
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Things to Consider When Buying a GRBL Controller

Laser or CNC Support

You should specifically check whether the GRBL controller board supports your machine type (laser or CNC). Some GRBL controllers only support CNCs, while others only support lasers.

Some GRBL controller boards for lasers support only 12V input and output. Plus, some of them don’t even have a Z-axis for CNCs. 

Spindle Capabilities

Many hobbyist CNCs switch the spindle directly with the GRBL controller board (although I advise against this). So, if you plan on doing this, you’ll need a GRBL board that can switch your spindle.

Some GRBL CNC controllers can only switch 24V spindles, while more powerful GRBL controllers can switch up to 48V spindles. Some GRBL boards can switch low-powered spindles (under 240W), so ensure you check the spindle switch’s wattage rating. 

Spindle VFD and Speed Control

If you’re using a VFD to control your spindle, you need a GRBL controller board with 0-10V analog output. This also depends on your VFD, but most require a 0-10V input.

Ordinary GRBL controllers only have up to 5V PWM for speed control. Therefore, they can only send commands to turn the spindle at half its full speed. However, with the correct electronics, your GRBL CNC controller can use the spindle’s full speed.

Dual Motor Axis Support + Number of Axis

If your machine has three stepper motors for X, Y, and Z, or two stepper motors (for X and Y), you don’t need to worry about this. However, some machines have two stepper motors on the Y-axis.

In this case, you should choose a GRBL CNC controller that supports dual axis. Some GRBL controller boards support an XYY configuration for lasers or plasma cutters.

Additionally, if you have a CNC machine with a dual axis, you’ll need a GRBL controller board that supports 4 stepper motors for an XYYZ configuration.

Stepper Motor Compatibility

Your stepper motors can fry the GRBL board if they draw excessive currents from it. So, your GRBL CNC controller board should be compatible with your stepper motors’ current ratings.

Most GRBL controller boards employ A4988 or DRV8825 stepper motor drivers, and can generate 2A per stepper motor. However, it’s best to only use them up to 1.5A, though with a proper air fan, you can draw up to 1.75A. These are good for some NEMA 17 stepper motors. 

However, some GRBL controller boards are more powerful. For example, you can easily use BlackBox Motion for most NEMA 23 stepper motors, as it can generate up to 3A per stepper motor.

Power Supply Compatibility

Some GRBL CNC controllers accept only a specific voltage input (for example, 12V or 24V), while others accept a range of voltages. If you’re buying a GRBL controller for a CNC, buy one that accepts at least 24V. However, 12V is adequate for a laser cutter/engraver.

Lower voltages result in weaker stepper motor performance in CNCs, especially if the CNC has more powerful stepper motors.

Accessory Support

The accessories include limit switches, offline controllers, probes, and motors. All GRBL controllers support at least one limit switch per axis. However, most GRBL controllers support two limit switches per axis (6 total limit switches).

Having a Z-probe also helps to find the material’s surface coordinate. Some GRBL controllers like BlackBox Motion control support probes on all axes.

Offline control allows you to connect to the GRBL controller with an offline controller. You can jog the machine or switch the spindle with an offline controller.

Finally, if you want to switch coolants or pumps directly with the GRBL CNC controller, make sure the board supports these. 

Replaceable Stepper Motor Drivers

Some GRBL controller boards have a replaceable stick driver design. 

Let’s say you have jammed the Z-axis stepper motor driver: you can just take it out of the GRBL board and replace it. 

However, most ready GRBL controllers have soldered drivers (unlike most DIY shields). With these GRBL boards, you may have to replace the whole board after burning a driver (if it’s inexpensive). 


Generally, documentation is essential for easy wiring. For example, Shapeoko makes decent GRBL CNC controllers, however, there is no documentation on them. So, they’re only really appropriate for Shapeoko CNCs because Shapeoko users can just plug in the sockets, whereas other users will run into trouble finding the spindle and other pins on the board.

Read more:

You can build or buy a GRBL controller board; I’ve previously covered this extensively. My previous GRBL builds (and other Arduino CNC controllers) were because I needed special things that normal GRBL controller boards couldn’t do, but you might not need these uses. You can read this and this article on building G2Core controllers and on connecting stepper motors to an Arduino if you want to get your hands dirty.

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Leo Watts

Leo is a head writer and editor for CNCSourced, having been an engineer for a number of years. I have an MS in Control Engineering and have designed and built several automation systems for PLCs. I built my own CNC machine from scratch a few years back, welding metals to make a rigid CNC body, and making CNC control systems for powerful motors. I gained unique experiences both building and working with that DIY CNC machine, and I’ve figured out ways to cheaply cut granite and stone with a unique trick (check my guide for this). If you have any questions, you can reach me at [email protected]

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