30-50w laser diode - cutting project

[work]

hi guys, i am trying to build my first laser cutter cnc machine, and i need some help... i hope the post is in the correct section and i will get a few answers...
i don't want to use co2 laser for my laser cutter... i really don't like them
now, i have the option to buy a used laser diode coherent... but i don't know nothing about it, hours of use etc. I know it may fail quickly, so ... i am willing to give it a shot just to see it working and cutting something....
basically i want to cut trough 1-5 mm soft materials like (cardboard, plexiglas, plywood, etc) maybe engrave some aluminium or steel
the diode power is 30 watts wave 877nm, and it works unde 2v and about 30amps... i know for sure if you apply 35amps it will provide 35watts (i won't risk that unless i have it and it's useless, just for fun)
the million dollar question is:
30 watt diode laser will equal with 30 watt co2 laser? what is the difference?
also i saw on youtube those diodes comes without any output optics... si i will have to focus the beam at the diode enclosure exit point, then drive it trough mirrors to the cutter head which will focus the beam more precise and prepare it for cuts.
is this correct?
there is a youtube video where it's used a 60w diode, and after a while of use the lens that focuses the beam explodes, i assume because of the heating? how can you avoid that?


any suggestion or information will be much appreciated.


thank you!

[VDX]

... the diode is NIR (Near InfraRed) with mostly 808nm wavelength, whats not usefull to cut bright/translucent/transparent materials -- it will simply shine through or reflect diffuse without heating the material ... while a CO2-laser has a wavelength of 10640nm, what's perfect absorbed in all organic materials.

Another flaw is the minimum output beam diameter, what's mostly a bundle of 19 fibers out of a FSMA-connector with roughly 0.8mm diameter, what's best focussed to maybe 0.7mm spot diameter, while a 30Watt CO2-laser is focussed to maybe 0.03mm best.

So this IR-diodes, while nominal in the same power range, aren't usefull for engraving or cutting

Viktor

[work]

Thank you Victor for your reply!
In this case i will consider using a co2 laser... i thought a laser diode will do this job, but it seems it doesn't.

[VDX]

... if you're not limited to clear acrylic and plywood - i'm engraving all sorts of other materials or cutting cardboard or plastic sheets with 'blue' 2W@445nm-diodes.

If you're interested in some more infos, you can start here - http://forums.reprap.org/list.php?133

Viktor

[work]

so, basically as long as the material is not transparent i can cut with this NIR fiber laser diode right?
i think i am going for a co2 laser... i think 80w will do it's job to cut 3-5mm wood/plywood, any kind and color of acrylic, etc
BUT
the market is full of co2 laser tubes that varies from $99 in china to a $2k for a powerful laser
is there a brand or something which point for a quality co2 laser tube?
i am tempted to buy the cheapest one, but not always the cheapest is good or the most expensive is the best...
any idea?

thanks again!

[swamidog]

so, basically as long as the material is not transparent i can cut with this NIR fiber laser diode right?
i think i am going for a co2 laser... i think 80w will do it's job to cut 3-5mm wood/plywood, any kind and color of acrylic, etc
BUT
the market is full of co2 laser tubes that varies from $99 in china to a $2k for a powerful laser
is there a brand or something which point for a quality co2 laser tube?
i am tempted to buy the cheapest one, but not always the cheapest is good or the most expensive is the best...
any idea?

thanks again!

if you're in the US, i strongly suggest http://www.lightobject.com

that's where i bought the parts to construct my 60W co2 laser cutter.

[work]

swamidog, thanks for your suggestion, however i am not in US but i have the awc608 controller+power supply + stepper drivers.
I only need co2 laser tube+high voltage power supply and all the mirrors/optics to drive the beam and cut.
an 40w co2 laser on lightobject is $185... in china costs $99, it's like double the price...i`m not saying it's an average co2 laser tube from china, but it there is no brand on it, and pictures look similar with the ones from alibaba....
i don't want the pay double and get the same quality....

[VDX]

... the quality of the cheap chinese CO2-lasertubes is highly variable ... even for the same type from the same vendor!!

Small (<100W) industry grade CO2-lasers are mostly sealed aluminium- or ceramic-tubes with 10x to 20x lifetime-expectations and much more precise controlling/pulsing abilities ... but will cost from 2000€ up for a 'refurbished' (refilled custom-laser) 30W laser ...

Viktor

[work]

well, it looks like i must rely on luck on this purchase
basically i am interested to cut some materials for architectural models (plywood/balsa/acrylic sheets) with 40-60w co2 laser will be more then enough. if the tube life is 3-4000hours and it cut those materials it's enough for me.

thanks!

[VDX]

... expect a 'lifetime' of 100 to 500 hours until the power will decrease rapidly - 3000 to 5000 hours until gas-exchange/refurbishment is only valid for the 'proffessional' brands ...

Viktor