China K40 conversion to Arduino

I jumped into the boat of people getting rid of the dreadded Moshi soft- and hardware.
Using a slightly modified Marlin release by Turnkey Tyranny and the corresponding Inkscape extension the machine now runs very smooth for both raster and vector works.
As I am too lazy to do all the writing twice and the copy and paste did not give proper results I just refer to my Instructable about the conversion process.
The above is the first stpe of the process, basically just a direct swap for the original controller.
In the next round I will address the safety features, add a display with encoder and full SD support to get an independent machine.
For the final round it is planned to integrate things like water pump- and compressor control into the firmware as well as adding Wifi connectivity if possible within the limits of the 16MHz clock of the Arduino Mega.
I am not claiming to be the genius behind the work as all the hard stuff was done by the Lansing Makers Group and Turnkey Tyranny, I just modified the Marlin Firmware a bit to suit my machine.

Hi there, thanks for the 'instrucable'

I'm part way through the same conversion on a K40.. And i'm currently using the 'Lansing Makers Group and Turnkey Tyranny' modified Marlin firmware.

I wondered how you jog your laser prior to running a job (to align the material with the program origin) - any jog moves I make through repetier or similar fire the laser?

Thanks. Mike.

... you need a dedicated I/O-pin to "arm" or "disarm" the laser, which you have to set for every line or dot to engrave ..

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Hi Victor,

Thanks for the info - to be clear, I need an additional output (on top of the laser fire and PWM output that I already have)?

Thanks again.

... not exactly - you'll need an activating mode for your PWM output -- if "armed", the PWM will fire your laser, if not, then it will move without laser burning.

I'm doing this either per software (sometimes I'm using the E0 STEP pin), or with an Arduino in my laserdriver, which has inputs for "LASER ON" and pulse/PWM, to sort this out on his own.

An "oldstyle" methode is to feed the PWM for the laser together with an "activating" signal through an IC (e.g. a 74-IC with AND or NAND gates) - but this is mostly done with common laserdrivers, so I'm wonder, why you have this problem ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

I see, I think the issue is that jog commands are actually G1 moves sent from the repetier - and looking at the firmware the laser would fire given a G1 move. I just wondered how and if other people worked around this scenario?

Maybe I could just put a switch inline with other interlocks to prevent the laser from firing while I am aligning the start point.

Cheers.

... industrial lasers have several security measures and interlock-switches - there it's often a key-switch for "arming" the laser.

But yes, you can insert a switch to activate the laser per hardware -- or an aditional (AND) I/O-pin to set it per software ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

No experience here, just an observation;

I think you should check that you have an interlock on the door.

It can be done very simply by passing the "arm" pin as per VDX suggestion through a microswitch attached to the body, that switch is then closed when the door is closed. That way the software controlled ARM signal can only reach the laser if the microswitch is closed (the cover is closed). Very simple way of increasing safety a lot.

How do you align the part with the door closed or an unarmed Diode?
You can't reach the part, nor see the dot.

I'd simply reduce diode current to a bare minimum and use safety goggles to align the part.

edit: forget what I wrote about seeing the dot, we are talking about CO2 lasers, DOH...

Edited 1 time(s). Last edit at 07/31/2016 05:21AM by o_lampe.

... with my lasers I'm either engraving a square or burning a dot into the (temporary) base for pre-alignment, or adding a camera for optical fine-positioning/adjusting the origin with some ten microns accuracy ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]