CNC spindle interface adaptation for laser head

[Christophe Mineau]

Hi,
Here is something maybe very specific, but that could be of interest for CNC mill owners.
The goal is actually to adapt a laser head instead of the spindle in order to perform some engraving, or cutting or whatever...
There are different challenges, hardware and software.
Here I'll address only the hardware part.
The main difficulty is to trigger the laser diode by the CNC controller board, and not only just powering it on or off, but also
controlling the optical power.
Most of the CNCs (at least most of the hobbyist grade CNC's) control the spindle using a VFD drive, and two or three outputs are used from the controller board:
- 1 or two digital output to command the CW run or CCW run
- 1 analog output providing an anlog signal between 0 and 10V for scaling the spindle speed between 0 and its max speed.

On the other hand most of the laser heads use a single PWM signal to set the power of the diode.
0% duty cycle meaning diode off, and 100% duty cycle meaning diode on, with all intermediate settings possible.

So, in my case, I was about to make myself this 0<10V DC to PWM TTL converter, but searching what was already available, I found a small conversion board that did exactly the trick:



The name is "Fasizi 2 modules PWM de 0 V à 5 V/0 V à 10 V de 0 à 100 % de tension de signal PWM" on French Amaz...

It also requires an external 12V power supply, for that, at least for the moment, I decided to use my usual bench power supply .

Now I had to decide how to enclose this.
I wanted to have it removable, as the main usage of my machine will keep for milling.
I looked around and decided to go with this small round metal box (cosmetic cream container).



You'll see later why this turned out to be a good choice.

First I drilled a couple of holes, (using a stepped drill) and inserted some plastic rings to protect the wires that will go through :


Next I had to insulate the inside of the box, I used Kapton tape to do this:


Here is everything wired :
On the left, the long cable that connects the head : GND, 12V, PWM signal.
On top the 12V input power (banana plugs to fit my bench top power supply)
On the right : a DB 9 connector that plugs into my CNC controller board (CSMIO IP/M from CsLab)


And then I realized that I had enough room yet in that box, and I could tidy up the wires in it when not used.
I improvised these notches on the edge of the box, to let the wires re-enter the box.


And here is the complete assembly:
On the right you can see the laser head.


And here is the beauty of the thing : when not in use, everything goes back to the box :

[DIYer]

Thanks Christophe Mineau! We've added your CNC Spindle Laser Adaptation to our CNC category,
as well as to your builder page: Christophe Mineau's Homemade Tools. Your receipt:

CNC Spindle Laser Adaptation by Christophe Mineau

tags: laser, CNC

[tonyfoale]

Christophe,

The english for your "plastic rings" is grommets. You might qualify that by "Rubber grommets" or "Plastic grommets" but usually just grommets is enough.
Nice post as we have come to expect. A year or back I converted an old 3D printer to a laser engraver and just used the motor control 0 to 10 V PWM signal to control the laser power.

[Christophe Mineau]

Hi, thanks Tony, yes, I must say, I didn't know the word for that grommets, sorry for the approximation
You say O to 10V PWM ? In my case, the required PWM for the laser is TTL (logical 0/5V).
But I know there are some lasers that accept also a 0-10V dc for power modulation, but this limits the choice.
What soft do you use to generate you gcode for laser engraving ?

[tonyfoale]

Hi, thanks Tony, yes, I must say, I didn't know the word for that grommets, sorry for the approximation

Apologises not necessary. I doubt that most native English speakers would know the word, unless they had some technical interest.

You say O to 10V PWM ? In my case, the required PWM for the laser is TTL (logical 0/5V).
But I know there are some lasers that accept also a 0-10V dc for power modulation, but this limits the choice.

Yes, I did say that but I was wrong. I should have said 0-5V TTL. My age damaged memory playing tricks again.

What soft do you use to generate you gcode for laser engraving ?

LaserGRBL. See my post from last November Laser engraver/cutter from old 3D printer. which explains the software in some depth.

[Christophe Mineau]

Thanks Tony, I will study that, I missed this post, how could I ?
Read you soon
Christophe

[Saltfever]

Thanks to both of you for sharing your ideas and experiences here and in the other link. The combination of opinions in both links covers a broad spectrum of motion control technology and is an excellent overview of some of the issues to watch out for. Have either of you considered Path Pilot?

It is both a computer and user interface and maybe solves some of the OS issues. Tormach tech only supports their machines and not DIY Path Pilot applications even though they sell the CPU and software separately. I was wondering if they would be a good approach for someone with less experience than you.

[tonyfoale]

Thanks to both of you for sharing your ideas and experiences here and in the other link. The combination of opinions in both links covers a broad spectrum of motion control technology and is an excellent overview of some of the issues to watch out for. Have either of you considered Path Pilot?

It is both a computer and user interface and maybe solves some of the OS issues. Tormach tech only supports their machines and not DIY Path Pilot applications even though they sell the CPU and software separately. I was wondering if they would be a good approach for someone with less experience than you.

Kirk,

I know about Path Pilot. Tormach initially used a customised version of Mach3 but for Path Pilot they jumped ship and based that on LinuxCNC. It is no good for me because it is aimed at steppers not the DC servos that my mill has.

For those with "less experience" as you put it then I think that the offerings from Cslab in Poland (that Christophe mentioned) or the offerings of Centroid in the US would be good options. Maybe not the cheapest but they both would only require mechanical work to get them up and running. Fitting motors etc. Programming and electronic stuff is taken care of for you. Both of these companies can supply systems to suit most motor/encoder combinations. Steppers, DC or AC servos.

For the budget conscious who want to avoid programming but who can do some simple wiring then I would suggest GRBL or better grblHAL to feed the motor drivers combined with some freeware like UGS https://universalgcodesender.com/ to feed the G-code to the controller. There are suppliers who have grblHAL breakout boards ready to drive motor controllers for around $100 with these you have no more wiring to do than the Cslab or Centroid.

You can also buy dedicated controllers from the east, many of which are based on GRBL anyway. AFAIK with these controllers you do not need a PC. Of course that means that you do not have the power of a PC to prepare your files etc.

[Saltfever]

Thanks again, Tony for the advise and the link. For all of us "Time" is our most precious commodity and we all ration it to pursue our individual interests. In the last 20 years so much computer horsepower has become available for "Makers" it's become an exercise in choosing where to focus one's attention to accomplish our goals. How far do we go on the DIY side of electronics vs. utilizing ready made systems. Thank you for defining the level of expertise needed and further defining the environment.

[Christophe Mineau]

Thanks again, Tony for the advise and the link. For all of us "Time" is our most precious commodity and we all ration it to pursue our individual interests. In the last 20 years so much computer horsepower has become available for "Makers" it's become an exercise in choosing where to focus one's attention to accomplish our goals. How far do we go on the DIY side of electronics vs. utilizing ready made systems. ....

All that is very well said, and for me it's always a struggle to balance between tool making and project making, and I must admit that tooling is for me the source for a lot of pleasure, and at the end, each projet is the opportunity for making a new tool
Fortunately for me, all this keeps a hobby and if I had to think about it economically, it would be different.

To come back to CNC machines, I would be glad to, and will probably will one day, make myself my own machine from scratch, but the ready made Chinese machines (I mean desktop router machines) are really great to start with, and starting from there, if you know what you do, you can upgrade, here and there, that's what I am doing with the change of control board, and addition of laser for instance.

I fully agree with Tony's post just above, and if I may add about the CSMIO from Cslab possibility, it is relatively easy to put in place, and what is really nice, it is really really well documented.
Just have a quick look at the documentation :
https://en.cs-lab.eu/wp-content/uplo...oipm_en_v3.pdf
This is a European company, and as far as what I can see on different forums, people in the US tend to use ESS Ethernet Smooth Stepper boards which seam to be at the same level of reliability.
And for Path Pilot, I'm sorry, I don't know that product. I can see that al number of people prefer to use what they call standalone solutions, a simple box and display, a few buttons and a usb port to plug your usb stick with your files, and that's it. Why not...