Status of my CNC router project

[Lars Berntzon]

Picture of my project building my own CNC router. It is kind of working. Using stepper motors an Linux CNC for controlling, via an Arduino board.
Next step will be mounting a 3D printer head and perhaps a DVD laser for cutting very thing things like paper.

[Jerry]

If you use a DVD/BR diode you MUST put it in a light tight enclosure. The specular reflection alone is enough to cause instant and permanent retinal damage.

Look at using a small chinese CO2 laser tube and power supply instead.

[Lars Berntzon]

That would be even better of course, but the quick checks I have made gives that getting a co2 laser and a laser-head will cost quite a lot.
Then you need some mirror arrangements for directing the light, or do you place the laser tube directly on the Z-axsis location?

Also, isn't co2 much more dangerous than a DVD-laser? They are in the range of 40-100 w, whereas a DVD-laser is probably less than 1 watt?

Regards, Lars

[Jerry]

That would be even better of course, but the quick checks I have made gives that getting a co2 laser and a laser-head will cost quite a lot.
Then you need some mirror arrangements for directing the light, or do you place the laser tube directly on the Z-axsis location?

Also, isn't co2 much more dangerous than a DVD-laser? They are in the range of 40-100 w, whereas a DVD-laser is probably less than 1 watt?

Regards, Lars

A 40 watt tube is about $100 and another $100 for a power supply. Pretty darn cheap. You use mirrors to bounce the beam to the spot.

A CO2 laser is much safer. The wavelength is far IR so it does not penetrate most things that we consider clear. For example glass, acrylic, and polycarbonate are all 100% opaque to this wavelength. So it is easy to build an enclosure for it. It also cannot penetrate your eye past the cornea, it is impossible to get retinal damage.

Visible lasers suck for cutting most things and diode lasers are the worst of the bunch. They have horrible beam characteristics that make the spot oblong without correction optics and then they are very difficult to focus down to a small spot, especially the more powerful diodes as they tend to want to run multimode.

Plus at the low power of a DVD or bluray diode you would have such a slow machine it would be almost useless. Light materials would be difficult to cut as well.

[Lars Berntzon]

Hm, I did not know that CO2 was less harmfull, but it makes sense of course when you think about it does not penetrate as good as visible light.

You also need the mirrors and a lens for CO2 I guess, so its about another $100, still getting a complete CO2 setup for 3-400 USD is quite ok. Previous checks me and my friend did suggested the total would cost about more like $30.000 but obviously it does not need to.

About the beam from a diode laser, you absolutely need a collimination lens but then you can focus it down to just a couple of micrometers (as its done on DVD-writer/readers), but I suppose you would like to have that for a CO2 right? At least to focus the beam somewhat.
Regards, Lars

[Jerry]

You can get parts and stuff from Lightobject who imports chinese stuff at a good price or get them from china directly.

Collimation does not fix beam astigmatism. You need different optics for that. And unless you want to cut real, real slow you will need at least 5 to 10 watts of power.

[Doug Coulter]

Jerry is on the money here. I have a big Nd:YAG I'm practically afraid to fire up because of those issues - at 1.06 nm it can get through your eye lens in focus, bounces off or goes through even black stuff...and has 60j output per pulse, so it's not wimpy. Edmund optical says they can't make optics it won't just fry on the first pulse. You want enough, but not enough to punch holes in things you don't want holed. 10 nm is just better for most things.

[johnf]

nm?

um =yes

[Doug Coulter]

Oops.