K40 controller review

When replacing or upgrading your K40’s controller, how do you choose the right option for you? In this K40 controller desktop review, we cover your options.

You are here… M2 Nano board

Our K40 controller review starts with the M2 Nano board which looks like this.

K40 controller board - Nano M2
M2 Nano board from Lihuiyi

It is the standard controller that ships with each K40 laser. It’s just a motion controller which has not been integrated with the K40’s digital control panel for laser power.

Disadvantages include:

  • It has very limited control of cutting in corners, which is likely to result in burnt corner points
  • It provides only dither-mode engraving. This simply means it can only switch on/off at one set power level, so you miss out on the improved images that gray-scale engraving brings
  • It’s expensive for what it is – outdated technology
  • It runs an unknown propriety form of G-code, making it hard to work with. The work-around is to use theK40whisperer software which emulates the proprietary G-code so that your K40 can be accessed by software other than MoshiDraw / LaserDraw / CorelDraw.

Things that matter

Before we step through available controllers in this K40 controller review, let’s be clear on what factors matter….

  • Ease of upgrade (the technical effort and complexity)
  • Engraving and cutting speed
  • Quality of the engraved images – gray scale looks better than dithering, and 16 bit is much better than 8 bit.
  • 3rd-axis capability – for some users, the ability to control a Z axis table or rotary via G-code can be important
  • Support – some products have no support, and you’re reliant on the goodwill/knowledge of the user community. You may prefer a product that has dedicated support provided by the vendor.
  • Overall Cost

Comparison Table


What matters

Ease of upgrade

Engraving speed 

Engraving options


3rd axis

Rotary plug

Overall rating




Plug &





Config & Wiring

2 X


8 bits

Mini Gerbil


Plug &

12 x

16 bits

Super Gerbil


Plug &


12 x


16 bits



Config & Wiring


Not specified

Not specified



Plug & Play

external power




? bits




3-6 X


Not specified

Details as known at time of publishing.

Technical descriptions

For those interested in the technical details, this section is for you. If not, skip to the Summary.

One of the key differentiators between controllers is their dialect of G-code. One kind is Grbl, an open source firmware. Smoothieware and TinyG are open source firmware derived from Grbl. Both provides G-code motion and laser power control.

DSP based controllers use G-code as input, but are expensive specialized circuits that really belong in their own category.

The K40 controller review list:

STM32 powered goodness
The small but mighty Mini Gerbil controller for K40 laser

Mini Gerbil: a recently designed replacement to a successful Kickstarter project. It uses a powerful (but cost effective) 32 bit Arm processor called STM32. It uses Grbl. The Mini Gerbil has dedicated firmware which optimizes the PWM, speed profiles and the USB communication. It comes in a neat little case.

Super Gerbil: a successful Kickstarter project offering up to 5 axis control for CNC, but is also applicable to lasers. Has all I/O coupled via opto- couplers to reduce electrical interference and noise. Also based on the 32 bit Arm processor STM32 . Uses Grbl. The Super Gerbil has dedicated firmware which optimizes the PWM, speed profiles and the USB communication.

Cohesion3D: these boards are based on the 32 bits LPC1768 ARM processor (dating from 2008). This board runs Grbl and Smoothie, comes with an SD card, display and Z-axis control. Unfortunately, at the time of writing we haven’t found specifications about the PWM resolution and speed.

TinyG: TinyG boards are based on the 8 bits AVR xmega192a3 processor but there’s limited information available. The board runs TinyG which has been derived from Grbl. Unfortunately, at the time of writing we haven’t found specifications about the PWM resolution and speed.

the absolute minimum option
A good old Arduino – great for STEM, not quite enough for K40 control

Arduino/Eleksmaker: these boards are based on the Arduino 8bits AVR processor. Their main disadvantage is the 8 bits PWM provides limited levels for laser power control – you won’t get quality gray scale engraving. Uses Grbl.

RUIDA DSP is a digital signal processor board used in the more expensive Chinese Lasers, offering faster motion and laser control than the Nano M2 board. The Ruida DSP controller comes with RDWorks, a CorelDRAW derivative. The only other working software we know of is LightBurn, but be prepared to spend more for the DSP specific version.


The comparison table reveals a large disparity in value. We suggest the following should be dropped from further consideration:

  • the M2 Nano controller – fewer features than cheaper alternatives, with the added disadvantage of limited software being only CorelDraw and Laser Draw.
  • DSP – their traditional speed advantage is under threat from the new generation controllers, and they have no other stand out features to justify their extreme cost.

Meanwhile, Arduino and TinyG lag on features. Arduino may work for the very low budget option if you’re prepared for some fiddling without dedicated support, whereas the TinyG doesn’t compete well at all in its price range. Oh, and don’t forget that Arduino’s hardly a speed machine.

Among the remaining, Mini Gerbil is a clear winner in the 2 axis stakes. In the battle for 3 axis controllers, Super Gerbil is a newer, better value product out-staging the older Cohesion 3D.

What have we missed ?

We’ve tried to simplify a relatively complex decision, and this may not take into account everyone’s needs. Who knows, maybe there’s someone out there who actually like CorelDraw ! Seriously though, we see a lot of interest in engraving, but if you’re a cutting-only guy or gal, this could change your best choice.

We didn’t review CNC related boards like PlanetCNC since we have no evidence that these boards are used in K40 laser machines.

If we’ve missed a decision factor of interest, or the summary isn’t quite complete, let us know in the comments below. We’re happy to update the table and blog.

Pssst, have you heard…

It’s no secret we sell the Gerbil products that topped this review. And it shouldn’t be a surprise they’ve come out on top – we purposefully designed them to address the gap between Arduino’s poor performance and features, and the poor value/features of the other products.

Interested in our products ? Here’s the links for Mini Gerbil and Super Gerbil.

13 thoughts on “K40 controller review”

  1. My K40 Laser came with a Ketai Gold3 controller board. My laser has the digital display. Unfortunately for me, it will only run on Corel Draw, and the supplier only provided a Chinese version! I tried installing the M 2 nano board, which did not work.
    Are you familiar with the Ketai Gold 3 board and if so, will a mini Gerbil work on my machine? Also, what software does it support?
    Thank you for providing the overview of controllers.

    1. From the pictures I can see it’s just a LiHuiyu Studio Labs boards which seems to be identical to the M2 Nano boards. Probably the dongle did not match the internal serial number. All connections are identical so it should work with the Mini Gerbil board. If not, I will refund you in full after returning the board.

  2. You won’t want to hear about this then… runs GRBL and all I had to do was jumper the end stop connector(3 wire) into a dual 2pin endstop cable. And it costs only ~$60 and like C3D it is based on the Smoothieboard so if Grbl isn’t your cup of tea, there’s Smoothieware too.

    [link removed by Awesome.Tech]

    1. Some people may copy our designs and IP. Such is life. If you’re a student and funds are thin, I understand you choose the absolute cheapest option. Just be mindful that you’re unlikely to get quality support and customer service, and you won’t have that warm feeling that you’re supporting innovation.

  3. Is the Super Gerbil plug and play with a K40 with a ribbon cable?

    I am looking to upgrade the brain of my K40. In the future I want to to do a rotary attachment and a bed height adjustment. It would be a nice to have a built in bed height control in software, but it is nit a need to have. I can electrically but manually adjust that if needed. How would bed height adjustment be handled in software with the super?

    How does rotary work with the super vs. the mini.? What does it mean by “rotary plug”? What does the wiring look like for that?

    Sorry for all the questions. Links to further reading are appreciated.

    1. Hi Super Gerbil has just screw terminals and no ribbon connector. However i will publish a middle men board for those interested. Maybe even produce a few and make them available on the supergerbil.com The height can be adjusted via the z axis which is integrated into the light burn software. The rotary can be on the y, a or b axis on the Super Gerbil while it plugs into the y axis plug on the Mini Gerbil. Hope this answers your questions.

  4. Hi,need some help,just installed gerbil but i have a couple of issues you may be able to help with,k40 laser,when i hit the home button in lightburn the head runs into the lower left gantry and wont stop,plus BIG issue is when the laser is running it does not alter power % nor does it stop when it rapid moves between items (laser will cut continuously)not going off between letters for example

    1. Best is to post on the K40 forum or email us. It’s likely that the X axis direction is inverted so use $3 to configure this. When the laser does stay on continuously, you have a loose PWM wire or the ground is floating. The latter happens when the power supply is taken out of the k40 case or is loose.

    1. Hi Alfonso, yes it does and is even better since it allows you do do even gray scale engraving next to dither. The M2Nano board does only dither engraving. Cheers!

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