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OpenBuilds BlackBox Review [2022]-Best GRBL Controller?



John Abraham
Hey I'm John. I write about Manufacturing, Metalworking, CNCs and Lasers at Mellowpine. If you have any questions related to CNCs or Lasers, I'd be happy to answer them. Reach me at mail@mellowpine.com


BlackBox mounted

The Openbuilds BlackBox is a plug-and-play GRBL based CNC motion control system that’s highly popular among CNC hobbyists.

An all-in-one plug-and-play control system takes away the need for wiring up your controller, and stepper drivers from scratch.

The BlackBox controller is capable of running CNC routers, plasma cutters, laser cutters, and CNC milling machines for hobbyist applications.

In this review, I discuss in detail what this controller can do for your CNC application.

OpenBuilds BlackBox Controller Review

OpenBuilds came out with the BlackBox controller in the year 2019, since then it has become one of the most popular controllers for CNC applications.

BlackBox controller has an open-source design. The makers, Openbuilds host a large community of CNC hobbyists and the community help can be invaluable while using the controller.

All the parts list, designs, and drawings of the controller are available on their website and if you want to do it yourself you can build your own BlackBox motion controller.

I evaluated the BlackBox for its price, axis support, build, external device support, connectivity, tool-head support, stepper drivers, and much more.

MellowPine is reader-supported. When you buy through links on my site, I may earn an affiliate commission at no extra cost to you.


BlackBox controller costs around $200 and is sold directly from Openbuild’s part store website. This price doesn’t include shipping charges and it will differ for different countries.

For $200 you’ll get a fully assembled BlackBox controller with a USB cable and Xtension connectors.

The price charged for Blackbox is comparable to that of other alternatives like xPro V5 controller.

Stepper Motor Capability

OpenBuilds BlackBox controller can drive four stepper motors with its high-powered 4.0A (peak current) Toshiba stepper drivers.

These Toshiba stepper drivers help you run high-torque stepper motors and allow up to 1/32 micro-stepping.

The front panel of the BlackBox has four current adjustment tuners through which you can adjust the stepper driver current.

Through the tuners, you can adjust the current of the X, Y, Z, and Y2 (slave) axis stepper motor individually.

Pushing the current too high can overheat the stepper driver. Only turn the tuner till where your motor doesn’t stall anymore under a normal operational environment.

Axis Support

BlackBox controller has three-axis support and can run all three axes independently.

However, you can make use of the slave driver to control an additional stepper motor for dual driving the Y-axis.

GRBL inherently has a limitation of being able to support only up to 3 axes, and this holds true for Blackbox as well.

There are, however, ports of GRBL that let you run 4 axis systems, like the xPRO v5 that runs on GRBL_ESP32.

External Device Support

BlackBox right side
BlackBox Controller – right side

Limit Switches

BlackBox has X, Y, and Z limit switch ports on its right side. All three end-stop ports are of the Xtension model, which means you can simply plug in the connectors without worrying about connecting them wrongly.

Your limit switch can be connected to the BlackBox with a 3-core cable. The limit switch can be mechanical or a powered one like a proximity sensor.

Height Probe

You can connect OpenBuilds XYZ Probe Plus and OpenBuilds Z Touch Plate to the BlackBox through a 3-core Xtension cable.

The OpenBuilds Z Touch Plate helps you zero the Z-axis while OpenBuilds XYZ Probe Plus helps you zero all three axes for proper operation of the CNC machine.


Though the controller doesn’t have a standard E-stop switch to halt the machine operation, it has a power switch.

You can use the power switch to bring the machine to an immediate stop. If you still want a dedicated E-stop button, you’ll have to wire one by yourself.

An E-stop switch can be wired between the power supply unit and the controller. OpenBuilds forum has a detailed community discussion on “E-stop wiring for BlackBox” that you can refer.

0-10 V Spindle

BlackBox controller provides 0-10 V output. It can be used to control common DC spindles which are used for engraving operations.

This 0-10 V output can also be used to control other tool-heads that require a 0-10 V signal to run.

PWM Spindle

BlackBox provides a 5V Pulse-Width Modulation (PWM) signal and it can be used to control low-powered tool-heads.

VFD Spindle

BlackBox controller can be used to control the Variable Frequency Drive (VFD) of VFD spindles using a 0-10V signal. This helps you run high-speed CNC spindles.

Door Interlock Signal Connector

BlackBox has a two-pin Xtension slot for connecting switches for detecting door position in routers with enclosure.

If you have such a switch wired to BlackBox, it will pause the cutting process whenever the door is open. It is a good safety feature to prevent accidents.

BlackBox left side
BlackBox Controller – left side

Coolant Output

BlackBox has a two-pin coolant output port that provides an output voltage of 24 V which is the same as its input voltage.

Coolant output is mainly used to connect different chip-evacuation, dust extraction, and cutting fluid systems. It can also be connected to control any other 24 V device.

To give you an example, it can be connected to the OpenBuilds LED Ring lights to turn it on/off during the machine operation.

Build of the Controller

BlackBox Controller – front and backside

OpenBuilds BlackBox controller is packed inside a V-slot compatible metal body, this provides a rigid enclosure to house the controller and makes it easy to mount onto your router’s chassis.

The enclosure has a footprint of 6.74″ x 3.15″ x 1.44″ and comes with mounting flanges. You can house it on the machine frame to reduce lengthy wirings.

BlackBox has a slim design with a muscle and brain configuration, where the muscle board provides the electrical power and a brain board provides processing power.

BlackBox has a built-in heat sink and a cooling fan to keep the controller at optimum operating temperature. The vents are on the backside, make sure to not obstruct the vents for efficient cooling.

The front panel of BlackBox has status LEDs which helps you by notifying the operating status through real-time feedback.

It has LED indicators to show:

  • Power status (red/green)
  • USB receive/transmit status (red/green)
  • Motor status
  • Axis fault
  • Probe input status
  • Coolant status
  • Tool status

The Controller

At the core of BlackBox’s brain board is an 8-bit ATmega328p chip flashed with GRBL 1.1 firmware.

ATmega328p chips are widely used in Arduino boards. OpenBuilds made use of the same ATmega328p chip without the non-essential components in Arduino boards to reduce space and give BlackBox a slim appearance.

OpenBuilds used the Arduino development platform for BlackBox and you can use the same GRBL firmware updates used on Arduino boards.

In case there are any firmware-related errors there is a hard reset button on the front panel of the BlackBox which helps restart the device which usually and resolves the errors.

Power Supply

BlackBox requires a 24 V power supply, make sure the power cable is connected with the correct polarity before turning it on, or else it could damage the controller.

OpenBuilds recommend using the 24 V Meanwell Power Supply for the BlackBox. The 24 V Meanwell power supply unit costs around $70 and is sold on the online OpenBuilds part store.


The connectors in the BlackBox are placed in well-planned locations across the left and right sides of the controller. This provides easy access and helps in effective cable management.

All the slots are clearly labeled and help you easily identify what to connect.

BlackBox is not capable of standalone operation and has to be connected to a computer through a USB-B cable as it doesn’t support WiFi/Bluetooth connectivity.

It can be connected and operated with computers running on Windows, Mac, and Linux OS.

Once the USB is connected to the computer, the USB indication LED will flash in red-green colors to indicate that data is receiving and transmitting from the controller.

You can control the controller through the OpenBuilds CONTROL software from a computer.


OpenBuilds CONTROL window
OpenBuilds CONTROL

BlackBox controller works in tandem with OpenBuilds CONTROL which is a CNC control software.

You can download and use OpenBuilds CONTROL from the OpenBuilds software website.

OpenBuilds CONTROL can work offline and runs on Windows, Mac, and Linux OS.

You might also need the OpenBuilds CAM software for generating G-codes that work with OpenBuilds CONTROL.

Both of these software programs are free to use and do not require you to pay for a license.

CNC Applications

OpenBuilds BlackBox controller can be used in CNC routers, plasma cutters, laser cutters, and in any other CNC machine for automated machining operations.

The BlackBox controller has an excellent track record of two years and has been tested with many popular CNC lathes and CNC mills.

CNC Retrofitting with BlackBox Controller

OpenBuilds BlackBox controller can be used with a great variety of CNC machines.

You can find a lot of CNCs retrofit builds with BlackBox controller in the OpenBuilds forum.

BlackBox has been successfully tested and used with some of the most popular 3-axis CNC machines out there.

OpenBuilds provides detailed manuals and explanations on how to use it and how far you can tweak the controller to achieve maximum performance.


OpenBuilds ships all the BlackBox motion controllers from the USA and they come in a well-packed sealed box.

BlackBox comes in a pre-assembled form, all you have to do is unbox and unwrap the air foam and wire it up with your CNC build.

The plug-and-play Xtension connection slots make it easy for you to connect all the different components.

Community and Support

OpenBuilds has a large and active maker community where they share builds and designs.

OpenBuilds also has a queued ticket-based customer support system on their website.

They can also be reached through phone/e-mail or by visiting the OpenBuilds online store.

OpenBuilds provides a one-year warranty for the BlackBox motion controller. When under warranty, you can claim repairs and replacements.

They also provide a 30-day return policy where you can either get a full refund or exchange the product.

Blackbox vs Mach3 with Ethernet SmoothStepper

BlackBoxEthernet SmoothStepper (ESS)
Stepper DriversFour 24 V, 5 ANone, need additional drivers
No. of axesThreeSix
SoftwareFree Grbl softwareMach 3 or Mach 4 (paid)

Comparison of BlackBox, ESS, and Buildbotics controllers

I’m comparing BlackBox with the Ethernet SmoothStepper (ESS) controller because its a popular alternative.

Both these controllers are widely used by hobbyists.

BlackBox is a three-axis controller while ESS is a six-axis controller. ESS can control up to six stepper motors for driving a machine.

Unlike BlackBox controllers, the ESS controller doesn’t come builtin with stepper drivers and has to be supplied with custom drivers.

The Gecko G540 is a good four-axis driver that is popularly used with ESS.

ESS uses a 5 V external power source and also provides only 5 V of power to the stepper motors.

This alone can’t drive the stepper motors and so external stepper drivers have to be utilized.

Whereas BlackBox comes with Toshiba stepper drivers which can run stepper motors with a maximum rating of 24V 4A.

Even if you buy an ESS controller, you’ll have to separately purchase a control software for it.

It works with both Mach 3 and Mach 4 control software.

OpenBuild freely provides their control software for you to use with the BlackBox controller and can be downloaded from their website.

The total cost of running a CNC with ESS would be the total cost of ESS controller, stepper drivers (like Gecko G540) and Mach 3 Software.

Whereas, the cost of running a CNC with blackbox controller would be the price of just the controller.

Both these controllers can run in offline mode but require a PC running with supported control software to operate the controllers.

Neither supports standalone operation but BlackBox can be connected with the INTERFACE CNC Touch control hardware to make it an offline GRBL controller.

ESS doesn’t come in an enclosed case and comes as an open board that doesn’t have any heat sink or cooling fan.

All that said, ESS is still a great choice to go for if you need high speeds and entry-level industrial-grade production quality as ESS paired with Mach3 or Mach4 software can run fast and powerful CNC routers.

ESS is the popular choice when it comes to CNC routers for production use like the Avid CNC PRO4896.

However, for hobbyist and DIY CNC builds, OpenBuilds BlackBox is preferred due to its affordability and the open source nature of GRBL.

Final Thoughts

BlackBox Controller mounted with a CNC machine
BlackBox Controller mounted with a CNC machine

The OpenBuilds BlackBox controller is a reliable and easy-to-use motion controller for your CNC machine.

Be it CNC routers, laser cutters, plasma cutters, or any other hobbyist CNC machine, the BlackBox controller can handle the task.

It is powered by an ATmega328p microcontroller running on standard GRBL 1.1 firmware and it receives regular firmware updates.

The BlackBox controller makes use of the OpenBuilds Xtension wiring system which gives the controller plug-and-play compatibility.

BlackBox has a compact design with a rigid metal build. The V-slot compatible mounting makes it easy to mount on most CNC machines.

You can pair the BlackBox controller with the OpenBuilds INTERFACE CNC Touch to operate the machine without a PC.

BlackBox being a product from OpenBuilds makes it even more attractive because of the large community.

You can explore various open-source CNC routers that are compatible with the BlackBox controller to build your dream CNC machine.

Frequently Asked Questions (FAQs)

Can I connect a laser cutter with the BlackBox controller?

Yes, you can. You can connect the BlackBox controller with Laser cutters, plasma cutters, and CNC routers.

While using it for laser cutting, remember to enable the laser mode in GRBL settings, else the laser won’t work.

You can connect a 12 V three-wire laser module or a 24 V four-wire laser module to the tool head slots of the BlackBox.

Will the BlackBox controller work without a computer?

The BlackBox controller alone can’t operate without a computer. It can be made to work without a computer if used with the INTERFACE CNC Touch.

OpenBuilds introduced INTERFACE CNC Touch to the market in the year 2020. It is a hardware alternative to the OpenBuilds Control software.

With the INTERFACE CNC Touch, you don’t need any software to manage your BlackBox controller. INTERFACE CNC Touch can be paired up with any controller running GRBL 1.1 firmware.

What all comes with the BlackBox controller?

If you purchase the BlackBox controller from the OpenBuilds online store you will get the assembled controller with Grbl 1.1 firmware flashed on it, the USB cable to connect to PC, and Xtension connectors.

John Abraham
Hey I'm John. I write about Manufacturing, Metalworking, CNCs and Lasers at Mellowpine. If you have any questions related to CNCs or Lasers, I'd be happy to answer them. Reach me at mail@mellowpine.com