Driver for cnc DIY

[maxvi22]

Hello everybody,

I try to build laser driver for my laser engraver with a dvd burner.
I made this following plan:

i chose red laser from dvd burner with 320mA therefore R1= 3,9ohm, 1watts.

After several try, the diode doesn't engrave paper... Have you got any ideas why ?

And last question, how to buy laser 650nm and 250-300mW please ?

Sorry for my bad English..
thanks all

Max

 

[ElectricPlasma]

Do you have a picture of your project?

I can't tell from just this if you've factored in a lens. You need to focus the laser to what you'd like to burn, and use something darker such as cardboard, the paper is white and will reflect most if not all of the red light coming from your diode. You'll need a bit of heatsinking for the diode too.

 

[maxvi22]

Hi ElectricPlasma,

Thanks for you help. I forgot specifying i have this diode housing:
2pcs 12x30mm Metal Housing Case FOR 5 6mm TO 18 Laser Diode W 200nm 1100nm Lens | eBay <=link
Maybe this diode housing is bad ? (With max focus, i have a still big red point).

I don't have laser picture because my diode is break (i try 400mA ...)
My problem from focus laser housing or laser diode from dvd burner...

Now the challenge is to find a diode laser for engrave....

 

[ElectricPlasma]

Hi ElectricPlasma,

Thanks for you help. I forgot specifying i have this diode housing:
2pcs 12x30mm Metal Housing Case FOR 5 6mm TO 18 Laser Diode W 200nm 1100nm Lens | eBay <=link
Maybe this diode housing is bad ? (With max focus, i have a still big red point).

I don't have laser picture because my diode is break (i try 400mA ...)
My problem from focus laser housing or laser diode from dvd burner...

Now the challenge is to find a diode laser for engrave....

You may have your lens on the wrong way if you can't seem to focus it to get a pinpoint focus. If you're engraving I'd use a Blu-ray diode (405nm) as it burns better because the smaller wavelength is easier to penetrate surfaces better than 650nm.

If you're looking for diodes, check out DTR and his laser shop here on the forum.

 

[Benm]

White paper could be a problem indeed. Red diode light is reflected off that very well, and you may find it problematic to cause any burning even if you have a single mode diode putting out 300 mW or so focussed to a small spot.

405 nm blu ray diodes work a lot better on many types of paper. The short wavelength causes the paper to fluoresce, and it converts some light to heat in that process. Once it gets hot it starts to discolor a bit and then it will absorb much more light.

You can see this with moderately powered lasers on paper: If you defocus the beam a bit, you get a situation where it takes quite a while for anything to happen. As soon as the paper starts to discolor it will absorb more light and the beam chews straight though very quickly.

With a red laser this could take ages as so little light is absorbed. It's not unrealistic for a beam to be on a piece of paper for a minute or so seemingly doing nothing, and then puching through within a second as soon as the paper gets the slightest bit of browning.

To prevent all of this you could start with colored paper that absorbs some of the light well, and you should be engraving/charring it at a good rate right away.

 

[maxvi22]

Hello,

Thank you very much for your assistance.
Good basis for start, can i buy this diode? :
https://sites.google.com/site/dtrlpf/home/diodes/bdr-209-405nm-16x-diodes

And follow this plan:

(for 40€, i'm taking certain precaution..)


I think you're right, blu-ray diode is a good idea. thank's for the lesson about this diode.
Max

 

[benmwv]

Make sure you get the glass lens upgrade when you buy the diode. High power 405nm will tear up that acrylic lens.

I think you can get rid of the transistor in the circuit if you hook it up like this:

So a high signal would turn it off and a low signal turns it on. Alternatively remove the diode between the arduino and lm317 and switch between high for on and high impedance (input mode) for off. I didn't test this but it should work considering how the lm317 functions. Basically it looks for 1.25v on the adj pin, if the voltage is higher is takes the diode current down until it achieves that and if its lower it takes the diode current up. 5v from the on the adj pin from the arduino will fully turn it off.

It should work just fine how you have it as well, this is just another option. If you decide to do it this way try it out on the breadboard first with an led or something to make sure it works.