Laser Engraving

it's all down to how long the laser is on for , the cooler it is the better it works , and the less stress it's under , which ultimately give you how long it will last !
they are highly susceptible to temp , humidity , voltage and current , and just about everything else on the planet , use the largest copper heatsink you can find , as you appear to want to do raster engraving.

Thanks cncbasher.
As computer CPU's also need to be cooled effectively, and I have several old fan-based CPU copper cooling units lying around, I will try and adapt one of these to cool the laser. I can then monitor the temperature as I slowly raise the power output of the laser.

Wow - I've just come across this website forum where a guy has produced near photographic quality laser "burning" of wood using a 1W 445nm laser and a shaft encoder to allow analogue modulation of the laser - not fukky sure how yet - I'm investigating - but I was sufficiently impressed to get the link out.

www.photonlexicon.com/forums/showthread....Shades-of-Grey-445nm

I've attached an example of his work - its impressive and I can see many uses in my guitar builds - easy ones would be mimicing flame maple and quilt maple patterns in the top veneers.

Sorry guys - didn't mean to put "not fu**y sure..." meant to be "not fully sure..." - slip of the fingers - don't flame me.

Micromet wrote: Wow - I've just come across this website forum where a guy has produced near photographic quality laser "burning" of wood using a 1W 445nm laser and a shaft encoder to allow analogue modulation of the laser - not fully sure how yet

I have read the article, and the answer is "he is doing it in the most stupid way possible"

He is taking the output from something like image-to-Gcode (which is built-in the LinuxCNC, by the way, just try opening a JPG in Axis instead of a G-code file). The then what would normally be a Z-axis move is actually turning a stepper motor that turns a bit of hardware that varies the laser power.

In a LinuxCNC setup you would instead take the Z-axis command signal in HAL direct to a PWMgen and take the PWM output to the laser diode.

Hi Andy,
Thanks for the info - again. I didn't know anything about the Image-to-Gcode ability in linuxcnc - have been using Gcodetools in Inkscape with mixed success. Also didn't know about the PVMgen option in linuxcnc. There are so many alleyways in linuxcnc.
Is there an example file somewhere that I can look at to see the protocol and typical text - I don't want to blow up my expensive laser diode.

Micromet wrote: Is there an example file somewhere that I can look at to see the protocol and typical text - I don't want to blow up my expensive laser diode.

Does the diode want PWM or does it need analogue voltage?

what diode driver are you using most use a pwm input , it's the driver that protects the diode
as it needs to be constant current , NOT constant voltage , so so long as it's meant for powering lasers
your ok . and it's set up of course to start with

Hi Andy and cncbasher. The diode I have is a 2W M140 blue 445nm diode laser from Jordan Ramey' DTR laser shop in the US (see sites.google.com/site/dtrlpf/home/diodes/445-m140-didoes ). Mine came with copper module and glass focussing lens. I also bought a 1.8A Buck X-drive driver for the laser( sites.google.com/site/dtrlpf/home/flexdrives/x-drive ). But I subsequently found out that the driver will only serve to provide a fixed output to the laser whereas I wanted to vary the output to perform different burning strengths. Contacting Jordan on this - he told me in reply to this question " can I control the output from the laser with the X-drive or do I need external control onto the power supply side of the X-drive" - and I quote "Yea the SXD has TTL input but the X-drive does not. You can lower the output of the X-drive by varying the input voltage under 6V manually if that works for you". The SXD is another driver that he supplies - and I probably should have got that but didn't.
I've ordered a 12V TTL 445nm power supply called the Walye Power A-10 from ebay. This has laser and TTL outputs
Now where I go from here I don't know - I evidently need to control the A-10 power board voltage output from within linuxcnc to vary the laser diode output but at this stage I don't have a manual for the A-10 so I don't know what other inputs/outputs it has until it arrives. The board has output voltage and current pots. Until it arrives I don't know whether it is feasible to replace these with digital pots and control their output from linuxcnc. According to Jordan I only need to vary the voltage. But I'm currently (pun not intended) out of my depth in terms of what I need to learn with regard to lasers. Luckily the Walye power board was cheap - so If its wrong it's not a great concern - bound to find some other use for it. Do you think it possible to put a PWM driver on the output of the A-10 before it goes into the X-drive and control the laser output that way? PWM drivers are easy and cheap enough to get on ebay. I will contact Jordan now for his input into PWM control of the laser.
If none of the above answers your questions - I can contact Jordan again with questions posed by you - I'm guessing that this PWM

Micromet wrote: I've ordered a 12V TTL 445nm power supply called the Walye Power A-10 from ebay. This has laser and TTL outputs

The TTL is almost certainly an input rather than an output. You would use this to turn the laser on and off from the parallel port.
Turn it on and off fast enough, and you have variable intensity control.

If you get the system set up so that you can control the laser on/off with coolant on/off (or whatever) then we can help you adapt that to use Z-axis height to set intensity.