controlling chinese laser power supply

[dominicburke200]

I am currently retrofitting a cheap chinese laser with new driver boards so i don't have to use their moshi draw program. i have now got the x,y working fine and am looking to connect the laser board. before i fry my computer i am just trying to find somone who can help me out.

i have attached a photo of my board

w }
r }-these go to potentiometer on control panel to control laser power
w }
k both k's are test button control
k
grd originally went to main driver control board
+5v

i currently have both grd and +5v disconnected and the laser still test fires by test button.
k,k and grd,5v both lead to 2x opto coupler on the laser board. i'm not sure the best way to connect the laser to my breakout board to control using pwm on mach3. i think it used to use the grd and +5v.
if you could point me in the correct direction on what connections to make.

Dominic,

[zax15uk]

Not sure if you have an answer or not, but these may help:

http://www.routoutcnc.co.uk/Forum/index.php?topic=17.0
http://alastair.d-silva.org/working-...aser-engravers

I haven't tried driving it directly as I'm happy with Newlydraw.

Zax.

[lasersafe1]

The original interface card puts out 5V on the "LASER" line to drive the front end of the optocoupler. You can hook this line to your breakout instead. If your breakout can't drive 5V, then you can pull it up with about 150 ohms and use a pulldown in your breakout to drive it in an inverted mode.

What I'm trying to say but finding it difficult is that I believe the optocoupler front end already has a built in current limiting resistor. You can drive it with 5V without a problem.

I hooked mine directly to the parallel port of the computer without issue, but this was my risk, not yours. I don't use a breakout board for my interface.

[dominicburke200]

thanks for your help. yes i can now control my laser using the grd and +5v to the breakout board. the x, y works fine and i can cut at a constant power. i am using mach3 and now want to try and get the pwm to work as i can only cut at the power specified on the control panel on the laser cutter.

can anyone give me a clue on the best way to wire up instead of this potentiometer on the control panel instead to my breakout board. there are 3 wires that i think i need to connect and also how to control it in mach3.
i think i have an idea about setting the spindle speed to 100 and then i should be able to set the % but i'm not sure.

if you need any photos of the wiring i would be very greatful as i have changed a low powered chinese engraver to a very powerful cutter which if anything is too powerful and cuts to quickly for my needs and would like to be able to lower the power to engrave again.
Dominic

[lasersafe1]

I have not played with the PWM features yet, but I can say the easiest thing to do for simple cutting is to wire your laser ON-OFF to the Z axis direction bit and program the Z axis speed to be maximum within the motor settings.

In this scenario, a standard G code written for milling will fire the laser when it has "dropped the milling bit" and turn off the laser when it is retracted. This assumes you are only doing milling without varying degrees of z depth.