My DIY Laser CNC build...

[Joelaw]

rusirius,

Thank you for a lot of information on your last . I have changed my settings to what I interrupted from your posting and am getting better results. I don't have a really good test picture and model to test. Just some jpg files I downloaded from the internet.

I am also using Birch plywood and Poplar but without sanding. I did not even think about sanding. Haven't tried it yet but will soon. I am still trying to tweek my controller.

Haven't gotten to play with the new controller because it will require a lot of changes to my system and a start over with settings. I also have to make a new breadboard of my Arduino with some changes to accomadate the new controller and Mach 3. You said that you are using the PWM output directly without an R/C to convert to analog. I will try this first and see what happens.

The pulse used to control the laser is now much cleaner since I installed rdh's recommended mods so everything is working pretty well now. I am still paranoid about blowing my 5th diode though.

I am trying to find information on lenses right now. I have about 10 and cannot tell which is which much less just the right one to use with my M-140 diode. I installed a new M-140 without driver in a new housing and cannot seem to get a good beam no matter which lens I am using. Just trial and error methods.

Joe L.

 

[rusirius]

Glad you're getting better results!

As for the pwm, I've actually just completed a bunch of testing and found something quite interesting. If I run the pwm to the driver direct the image reproduced is very accurate, however it doesn't produce the best results. I built an rc filter with about a 500uS response time and the image was slightly more pleasing. I built another with a 3mS response time and again more pleasing. I haven't tried anything higher yet, but I plan to. What I believe happens is that with a slower response time it basically "normalized" the pixels. So that large shifts from white to black right beside each other are brought closer to each other. It technically results in a less accurate image, but the final result is more pleasing to the eye. Think of it like the way a photographer will "blur" a person's face in a close up portrait. You'd think it would make it look worse, but it actually results in a much nicer image.

So now I've rigged a switch on my control panel, one way runs the straight pwm to the driver and the other way runs it through the rc filter. That way I can switch between the two.

What current are you running on the m140s? There are no data sheets on them, but looking at the data on power output to power input I'd guess in a continuous machine like this you don't want to push it any harder than 1.5A. Jeff who has a lot more experience with these diodes than I only runs his at 1.45A and has one that has logged thousands of hours. On the other hand, when he was running them at higher powers he was chewing through them in no time at all.

 

[Joelaw]

Please keep us posted with your filter results. I Am driving at 1.5 amps.

Joe L.