K40 Chinese laser conversion to Arduino

After fixing most of the issues on cheap laser cutter I am about to do the next step and install an Arduino board to get rid of the dongle and crappy controller.
I also would like to put this in the form of a nice Instructable so others can upgrade their machines as well.

But during my research I noticed that several different versions of the controller, laser power supply and control panel exist.
If you are interested in upgrading your machine so you can use Inkscape directly and no longer need a dongle and crappy software:
Post a pic of your laser power supply (including a clear pic of the connection terminals),
a pic of your control panel (both from the outside and the bottom),
let me know if you already have safety switches for the lid and water flow.

Everything posted here in time will be included in the Instructable if it is different from my machine.
Once the Ible is finnished you will get detailed instructions on what you need, how to program the Arduino, get the plugins working in Inkscape and how to do your first real engravings and cuttings on the new setup after calibrating everything.

Here is a video showing raster and vector engraving followed by cutting the piece out - what more can I ask for if only spare parts are used? ;)

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JorgeM641 year ago


This is my laser k40 recent conversion arduino controller

I used this diagram for the conversion for my power supply but the laser don't fire

and use this is marlin https://github.com/lansing-makers-network/buildlog...

Where is the problem ?

Any help me please


Downunder35m (author)  JorgeM641 year ago

I don't see the relation to my project, which I support.
Why would I check other projects ?
The Lansing group has great support in several forums, if use their mods and firmware it would be the best place to start.

I am sorry i know that is not related.

I've been looking and asking on other projects but not and received a response.

I'm a little desperate and i sought some solution.

I Try again with the marlin downloaded from your other post.

Thank you very much for your reply

I am grateful

Downunder35m (author)  JorgeM641 year ago

I understand your frunstration as I was in the same boat.
One problem is getting a firmware that really matches the machine the other problem is to make it fit if there are differences.
The later requires some knowledge of the topic or a lot of reading.
With my release I take the guesswork out as everything is made to fit the machine with as little modification as possible to the existing hardware.


I tried the marlin but the LCD screen does not work.

The laser if it works and the machine moves.

What is the problem?

You can help?

Downunder35m (author)  JorgeM641 year ago

I think the display might just be disabled.
Line 1152 in Configuration_Feature.h needs to be uncommented.
But I updated the files on Github accordingly, so you can just download the file and replace it.
Sorry for that but I did most of my testing without the display support and forgot to active it by default on Github - fixed now.

Downunder35m (author)  Downunder35m1 year ago

Not sure if you noticed but I moved on to a newer Marlin firmware.

Just so we are on the same page, this one is the one I am working with.

Downunder35m (author)  Downunder35m1 year ago

Sorry forgot to add the link - this one works just fine.

Downunder35m (author) 1 year ago

Today I did the conversion and although it really not the easiest job it was definately one of the most rewarding :)
Basically everything needed more or less mods to get it working.
The firmware was going haywire when I started a movement, homing did not work at all and when something moved it was dead slow.
The wiring was quite fancy too as it was necessary to add some pull up resistors for the endstops - the china guys sved even on this tiny item LOL
Also the diagrams I found did not mention the default stepping (1/64) for the machine and they did not fully match my machine.
The Inscape plugins required some tweaking too as their speed was too limited for the fine stepping used, before the mods the highest vector speed was just over 80mm/s, now the limit is set to 400mm/s which is good for engraving.
Will do some more tests and upload a video of the machine in action later on.
Still no DSP controller or proper printer driver for all programs but once I get used to Inkscape it should be all fine :)

Downunder35m (author)  Downunder35m1 year ago

Quick update:
While the general vector cutting and engraving works quite well I encountered some problems that need to be addressed to make me happy:
If a job is stopped and a new one started the laser fires at full power during the homing move - not good at all!
It can be avoided by manually turning the laser off, M5, and then home with G28 XY.
But for some reason the firmware often has a hickup after this and the machine refuses to moove until you disconnect and connect again.
During raster engravings I get bad vibrations at higher speeds and although it sounds like the motors loose the steps it works out, just with a lot of rattling noise.
In some cases the laser also fires too much resulting in bad burns or dark "pinholes".
If the speed is lowered to under 3000mm/min it works just fine, so I assume another Marlin related problem here.
From the G-code the print moves should be quite smooth and the acceleration is set quite low for the testing anyway, so maybe it is a timing problem with the stepping and print speed.

Using different layers to define how they got through the laser cutter is a great thing.
You can basically create your entire design in one big "image".
If you prefer you can use other programs for the job as long as you can export into a raster format Inscape can import.
But it means for the first time with this china toy I am able to engrave in raster and vector plus cutting pieces out in one single job.
No more wasted hours creating layers, exporting to a bitmap, just to see the machine is still unable to do a proper job.
Once I got the worst problems sorted I will start the ible and might even invest in a smart display with SD slot to make the machine independent from a computer.

Anyone with a dongle-crippled china laser willing to be a beta tester? ;)

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