New Machine Build- Laser, what and how?

[pupetxls]

Hello,

I'm planning to build a laser cutter machine. I'd use it to cut 2-3mm thick plywood, and acrylics. Plexy up to 10mm tops probably.

As machine, I'm pretty ok with everything, no questions here.
I do have questions about the lasers and the modus operandi of'em.

I've started to read the forums here and there, but I just get lost with all the info.

I have been looking for the Coletech CO2 lasers, I see their tubes, and as pricing they seem allright. It sounds too good in fact.

My questions are as follows:

a. - where do I need lenses? also what kind and what sizes? mirrors I assume depend on the machine setup.
b. - do I need some airflow to avoid flames on the cut?
c. - as of water cooling, can it be a DIY sistem with some household pump?
d. - lots of debates on software. I see splitting the laser and the motion. Why not use Mach 3 both for the motion control and the laser at once?
e. - what does a laser consists of? - power supply/laser tube/lenses/(mirrors?) and that's it? am I missing something here? what else do I need?
f. - I saw people using z axis for setting engraving or cutting. If I want to engrave, not cut, isn't it enough if I just raise the speed of the machine?
g. - longlife or normal tubes? I see different terms. Is it working hours and life span? seems cheaper to buy non longlife tubes and just change them in time...
h. - what W should I choose for my needs? 60W should it be enough? I'm worried about the kerf issue on 10mm plexy (in a weaker laser with a slower cut).
i. - where and how do I link the laser to my cnc driver? the driver that I use does have the ability to control mill or other equipment.

As I said before, at the point where I stand now, it seems too easy. If anybody would be kind enough to help I would highly apreciate it.

Thanks in advance,
Pupet

[bpoulin]

Hello,
I've started to read the forums here and there, but I just get lost with all the info.
If you're lost now, maybe consider buying instead of building a machine...
My questions are as follows:

a. - where do I need lenses? also what kind and what sizes? mirrors I assume depend on the machine setup.
The lens goes in laser head right above the material because your focus point is very close to the lens. And yes mirror size depends on your laser, and number of mirrors depends on your setup, Most Chinese lasers have 3 mirrors

b. - do I need some airflow to avoid flames on the cut?
It's not necessary but it is very helpful. Personally I wouldn't cut plywood without it. It can be achieved by air compressor or a heavy duty fish pump type of air pump. They are readily available on ebay. Air extraction is EXTREMELY important, engraving and cutting will create a LOT of smoke, so figure that into your project.

c. - as of water cooling, can it be a DIY sistem with some household pump?
It can be done on 60w or less systems, but I would say anything over 40w needs to have something to cool the water, like a radiator, and anything over 80w needs to have a chiller.

d. - lots of debates on software. I see splitting the laser and the motion. Why not use Mach 3 both for the motion control and the laser at once?
Because Mach 3 doesn't control the laser power on/off cycle fast enough. It needs to be done separately if you go the Mach 3 route. I am currently trying to find a good software replacement for chinese software.

e. - what does a laser consists of? - power supply/laser tube/lenses/(mirrors?) and that's it? am I missing something here? what else do I need?
This can get complex or stay simple, all depends on what you want out of your laser. You can have the power supply/laser tube/mirrors/lens, but then you can a collimeter, beam expander, beam combiner, beam splitter

f. - I saw people using z axis for setting engraving or cutting. If I want to engrave, not cut, isn't it enough if I just raise the speed of the machine?
Not exactly, engraving runs like a printer, it goes from side to side, etching your material, cutting will start at one point on a line and follow it. Imagine it like this, here is a circle 0 if you raster it, the laser will go right to left from the bottom to the top of the 0 until you have a 0 on your material. If you raster it (cut) it will pick a point (you designate in the software) and go around the 0 until it reaches the point it started and then stops. They are 2 totally different functions. Laser software doesn't do this, it has separate commands for engrave and cut. You really should look into software designed for the laser if you want it to work right. Mach 3 can do the job, but it's like saying microsoft paint is photo editing software...

g. - longlife or normal tubes? I see different terms. Is it working hours and life span? seems cheaper to buy non longlife tubes and just change them in time...
Again all depends on you, you can buy a used low power synrad for a few thousand, and it may last the next 10 years, or you can spend a few hundred on a higher power Chinese glass tube that will last a year or 2. It depends on what you want out of your machine, if you need the higher power, it would be worth it for you to buy cheaper tubes and replace them, but if you only need a lower wattage machine, a better laser may be the best choice. It's all about $$$ at that point. How much you have, and how much you want to part with.

h. - what W should I choose for my needs? 60W should it be enough? I'm worried about the kerf issue on 10mm plexy (in a weaker laser with a slower cut). Kerf really doesn't change with laser power, it changes with lens choices and DOF for the lens. A shallow DOF will give you very fine points and engraving but will have an hourglass effect on cutting.

i. - where and how do I link the laser to my cnc driver? the driver that I use does have the ability to control mill or other equipment.
Some control cards come with their own software, Leetro comes with lasercut 5.3, Full Spectrum has RetinaEngrave. I would search for a control card specific to lasers and not just CNC

As I said before, at the point where I stand now, it seems too easy. If anybody would be kind enough to help I would highly apreciate it.
If it seems easy, you need to look into it a little more It's not too hard, but it is a bit more complex than you seem to give it credit.
Thanks in advance,
Pupet
Hope this helps

[whmeade10]

I recommend going here buildlog.net - CNC Laser Buildlogs and building Bart's 2.x laser.

Cheers,
Bill