Re: [CAD_CAM_EDM_DRO] Laser Project ( was Re: Laser links ?

turbulatordude wrote:

> not knowing anything about lasers ( well, actually, I have 2 of those
> laser pointy thingies) what is the best place to start ?

Here's the outfit I mentioned with the laser kits :
http://www.emissiontechnologies.com/

>
> Seems the main questions are :
>
> Which style laser ? CO2 or YAG ?

CO2. Try to buy a good-sized YAG rod, and you will know why. You could spend
$15,000 for a decent rod and crack it by improper handling or power fluctuations
in the laser. Running 25,000 V flash lamps in circulating cooling water is also
not a technology for the novice! Even the experts have lots of problems with this.
We have some YAG lasers at work, they are used intermittantly, and they still
end up having to do a major rebuild every few months. It usually costs several
thousand $ to repair what gets blown up.

> What makes one harder to implement than the other ?
> more costly to run ?

CO2 gas, as the lasing medium, can't possibly be replaced by anything cheaper.
(If you want shorter wavelength, Nitrogen is about as cheap.) You can also
buy ready-made laser mixes from the specialty gas suppliers.

> If my math is right, a 2kw laser might need a 20kw power source. I
> have 220 at home so 20,000 watts / 220 = 91 amps ? I'm not sure if
> my electric meter spins that fast.
>
> did I miss anything ?

as the power goes up, you either have to spread out the beam (which can be very
difficult, the lasing action tends to crowd together) or obtain mirrors and optics
of higher and higher quality. Mirrors and lenses for a 2 KW output laser will
likely run $25,000 or more for the set. If you lens protection system doesn't
work well, then the lens could be destroyed at any time by a spurt of hot metal.
A tiny spec of dust on the lens could crack the lens, too. If your mirror protection
system is not good, then the lenses will be degraded by hot ions. Any dirt on the
mirrors could also crack them, but at least it is possible to keep them clean.

A 20 W CO2 laser is very doable at reasonable expense - several hundred $, if
you do most of the construction yourself. A 200 W laser is very difficult, but
with sufficient laser experience and access to surplus optics, it can be done
for a few thousand, probably. One of the best ways might be to get an older
laser with some worn-out parts, and rebuild.

a 2KW laser is just not practical for anyone without access to the Lawrence
Livermore Labs scrap pile or the assets of a small corporation. The average
experimenter should expect to spend something like $10,000 minimum on
this, using surplus optics and other parts. the availability of such surplus
parts is not a given!

One other concern with a 2 KW laser, is that at 10% efficiency (and that's
REAL good, even at IR wavelengths) you need 10 KW of pump power, and
8 KW goes into heating something other than the work. So, you'll need a
water chiller able to remove 8 KW of heat from the laser! You probably can't
get enough city water to carry off that much heat. So, you might need a dozen
or more truck radiators and fans.

>
> Dave
>
> ps $50 edm ? did I miss something

Not much, but see http://pico-systems.com/edm.html

Jon