[panoss]

I 've built a small cnc pen plotter based on GRBL (GRBL-28byj-48-Servo).

Inspired from:
this

It 's a version of GRBL modified for unipolar motors + the use of a servo motor for Z axis (that moves the pen up or down).
It 's working ok, now I want to modify it for a small 5mW laser pointer.
With this I want to make PCBs.
The points of the photosensitive PCB that will be exposed to laser will remain on the PCB (after development + etching, of course) while the non exposed area will be removed.

So, my question is how shall I switch on and off the driver (it 's an LM317 based driver) of the laser pointer.
Shall I have to modify the GRBL-28byj-48-Servo code?

If I replace the servo motor with a relay which will control the driver? And leave everything else as is? Will it work?
Maybe I should use some laser engraver software?
(With it as is by now (that is as a pen plotter) I use Inkscape + MI GRBL extension.)
Any help is welcome.


EDIT: I took a closer look at the diode 's driver and it uses a transistor for switching on and off the diode.

[terjeio]

5mW is a bit on the low side for exposing at any decent speed, I used a 100mW BluRay laser for my project.

The diode driver schematics I used for my exposer can be found at my Hackaday/Github project pages along with some other information that may be of use for you.

Controlling the driver with a relay could be problematic due to contact bouncing and slow response time, better to control it via a transistor switch as you found out.

[panoss]

Looks very nice! Exactly what I was searching for!
Can you post me a link where you bought the 100mW BluRay laser diode?
Or you salvaged it from a BluRay device?

[terjeio]

I have bought diodes from three different eBay sellers, just search for '405nm laser'. The brass housing and lens can be found by searching for 'brass laser host' - I bought mine from this seller.

Also, I have just updated the driver schematics on Hackaday if you intend to use that design - a resistor has been added to make it more robust.

Good luck!

[panoss]

What about this one? 100mW, 405nm, Dot-Violet. It has it 's driver and it 's focusable.

[terjeio]

Well, I can only say I initially bought a driver from eBay that turned out to be useless for my design due to its slow response time... Whether this is usable is something you have to try - I have no idea. Another problem may be controlling the output power of this - it seems to be non-adjustable, too much power and it will fog your exposure.

Perhaps it can work for you depending on how you intend to render the image, I am using rasterization and relatively high speed - if you are to do vector rendering at a slower speed perhaps the response time is not that critical? But then at a slower speed too much power may become a larger problem? IMO better use a driver that is adjustable...