Diode laser

Hello

I'm using LinuxCNC in my home made CNC for a couple of years. Its great software and I want to thank all involved in this project for making this possible.

Even if I’m using the software for same time I’m far from being an advanced user (so I need some advice). At the moment I’m considering installing a interchangeable diode laser whit the spindle. Is EMC2 capable of managing a diode laser?

Thanks, Vasco Reis

it depends on what you need the laser to do , cut ,etch or Burn ! etc , but all a laser needs is pwm circuit to vary the power level in most cases ..
people have used lasers with Linuxcnc . you will need to interface to the laser etc , as most require a constant current source .

their are some notes regarding lasers in the Wiki

Thanks.

Ill have a look in the wiki.

The objective is to cut /engrave. My problem, I'm guessing, is to turn on and of the laser because there is a way to go around the intensity problem, one can approach it like a tool change.

use M3 m5 to turn on or off the laser , as if it was a spindle , as Andy suggests varying the power of the laser for rasterising needs a bit more work .
i have used the spindle speed in the past to vary a laser for power using an A/D convertor .

diode lasers are good for burning , not so much for cutting , CO2 lasers at a wavelength of 10.6um are normaly used for cutting

My idea is to cut 1,5mm to 2mm balsa ... so I hope a diode laser is sufficient. Its not worth to go for a CO2 because of the technical problems and costs involved ...

No, a diode laser will not cut balsa. It will, however, light it on fire.

Diodes are really bad ideas for laser cutters. First they run in a wavelength that is in the visible to near-ir which is harder to shield from than co2 laser. Even a specular reflection with a strong diode will cause permanent eye damage.

Second the beam quality is crap and there is no real way to fix this short of using the laser to pump a crystal or fiber to get a good beam.

Third, the wavelength, the co2 laser is really suited to cutting organic, diodes, well, not so.

Look at a cheap chinese co2 laser tube and power supply off the internet. 40 watt is pretty cheap, shipping will almost cost more than anything else. The power supplies have a pwm in to control power and Ben Jackson over on Buildlog.org has done some work on controlling laser cutters with LinuxCNC and a 5i25.

Thanks. Just one more question. The reason I'm researching this topic is because it would be relatively simple to interchange the spindle whit a diode laser. Since in designing a new CNC machine I was thinking to do it in a way that could accommodate a diode laser, and that is not practical whit a CO2. Is it predictable that the diode laser evolve to the point that this feasible?

Combo laser cutter and cnc router sounds like a great idea but in practice it really does not work so hot. A laser cutter is a machine that is usually built light for quick movements like you see in raster engraving. There are no cutting forces involved so the machine can be built pretty light.

Routers, not so much. Unless you are thinking of a toy like a dremel router. Even then it helps to have mass on your side to dampen vibrations.

No, there will never be a point where a diode laser will be suitable for cutting. The closest thing you will find is a fiber laser, but you might want to be sitting down before you get a price on one of those. And frankly high power diodes should not be in the hands of amateurs as far as I am concerned. You see idiots all over youtube doing stupid stuff with them. CO2 lasers are much more forgiving. The wavelength is much longer than a visible diode, it is basically a coherent beam of heat. It does not penetrate most materials that we consider transparent. A generic polycarbonate face shield blocks 100% of the beam. So does glass and acrylic. Even if the beam got past your protective wear the light will not penetrate past your cornea which means you have a much better chance of recovering from eye damage. We have a 4400 watt co2 laser cutter at work that can cut 1" of steel, it has windows of about 1/4" plastic. That's all it takes.

One option is to move the table and not the router/optics. It takes up more space but does simplify things. One problem is dust. High power laser + dust = damaged optics.

If you do build a laser burner with a diode laser you MUST TOTALLY ENCLOSE IT. Completely light proof. If you need to see whats going on put a web cam inside. Do not rely on safety glasses like some people do. If someone were to walk in to the room bad things could happen.

Thanks ... Its time to rethink my idea.