[wwendorf]

Hi All,

I've been doing cnc for quite a few years and have been really interested in the lasers as well. I had enough with the cnc mill for now, but now i'm considering a laser again.

I'm a lot uneducated about lasers and I hope you can help me with a few questions. I was thinking about building one of those laser drivers out of a dvd burner for a first project just to do some engraving with. Then recently, I read about diode pumping lasers that seem to be able to go up to 380mw which is a more power than the dvd/cd lasers can go.

Just how powerful is one of those lasers? Could it for example cut 1/16" hobby ply or 1/16th balsa??? I know that it could cut metal, but just how good would one of those be for wood?

Next question is what kind of laser and what wattage laser would I need to cut something like 1/4" to 1/2" aluminum (6061-T3).

Thanks in advance,
wade

[zax15uk]

Wade,

There are many things to consider. Wavelength for example, as different materials have variable absorption. 380mW isn't much power though, and unlikely to cut any metal even when focused.

CO2 is efficient for cutting wood, a 25W RF excited metal tube or 40W glass tube would be sufficient for 1/16" ply at a fast cut rate.

Cutting 1/2" aluminum is a different problem, you'll require a several kilowatt CO2 laser to cut at any decent rate.

Diode pumped lasers, like Nd:YAG are great for engraving applications and can be used for drilling holes or cutting thin metals.

Zax.

[DaveDoesIT]

Cutting 1/2" aluminum is a different problem, you'll require a several kilowatt CO2 laser to cut at any decent rate.

Zax, you and I usually agree on stuff but I think you are being a bit conservative there. I would say "many" kilowatt. I'd say starting around 4,000W and close to 1/4Mil-dollars. :O

[CNCZILLA]

DaveDoesIT is correct. I know Trumph lasers which are top of the line and a new one in the 4000 watt range would tear 1.5 million all to pieces. However with this laser you will do what ever you want with most any material up to 1" steel easily and will also engrave, and if you haven't seen one of these things work then you would be amazed at what the new technology will do.

[Herbertkabi]

Please tell me what kind Laser (and minimum power) for small parts precise cutting of 0.01 ... 0.05 mm steel (ferrous) sheet?
cheers,
herbert

[wwendorf]

I was looking on ebay a bit more, and I found of those diode pumped lasers at 450mw. It said it was able to cut plastics and wood. I realize that 450mw isn't a lot, but if I were to try and cut 1/16th hobby ply with it, what do you think my cut speed would be?

Wade

[zax15uk]

Really S L O W... but it will eventually burn a hole in it, if it doesn't catch fire before then.

It will also melt plastic, rather than cut it (which is really vaporizing the material from the kerf).

I went down this road, and used a small (<1W) laser diode on my CNC system but was never able to cut anything but wood veneer with any quality. It did a great job of engraving but was still too slow so I ended up buying a cheap 40W (really a 35W) glass tube unit. It was a much better investment, so I would suggest skipping the 'waste of money' small diode part and moving to a CO2 if you want to cut 1/16" ply. Metal is of course a different subject as we already discussed.

Zax.

[wwendorf]

So, the next question is, do you have to use mirrors to aim the beam, or can you just mount the laser to your Z axis and let it fire straight down, while moving X and Z?

Wade

[zax15uk]

That is the advantage of a solid state laser compared to a glass tube, you can fix it directly on the Z-axis and eliminate the need for mirrors etc.

Zax.

[DaveDoesIT]

Please tell me what kind Laser (and minimum power) for small parts precise cutting of 0.01 ... 0.05 mm steel (ferrous) sheet?

Herbert,

You need to do some research on Nd:Yag lasers for cutting metal. The CO2 lasers will not cut metal until in the 2000+ Watt range and they are BIG bucks.

The cheapest used Nd:Yag laser I have seen was around $16,000.

Dave

[methuso]

Really S L O W... but it will eventually burn a hole in it, if it doesn't catch fire before then.

It will also melt plastic, rather than cut it (which is really vaporizing the material from the kerf).

I went down this road, and used a small (<1W) laser diode on my CNC system but was never able to cut anything but wood veneer with any quality. It did a great job of engraving but was still too slow so I ended up buying a cheap 40W (really a 35W) glass tube unit. It was a much better investment, so I would suggest skipping the 'waste of money' small diode part and moving to a CO2 if you want to cut 1/16" ply. Metal is of course a different subject as we already discussed.

Zax.

Noobwarning:
Im thinking about buying a 40W tube too. what else is needed besides a compatible powersource, mirrors and a lens? the co2 is INSIDE the tube and do not need changing ?? is a aquariumpump enough for cooling?
best regards /Ulf

[Tweakie]

I used a small brushless pump and a CPU type fan assisted radiator for my water cooling.

Tweakie.

[methuso]

thanks.
but nothing missing it what i stated in previous post ?

btw. cutting balsa with a 300mW diod right now. PAINFULLY slow
/Ulf

[zax15uk]

Noobwarning:
Im thinking about buying a 40W tube too. what else is needed besides a compatible powersource, mirrors and a lens? the co2 is INSIDE the tube and do not need changing ?? is a aquariumpump enough for cooling?
best regards /Ulf

Ulf,

That is everything you need, I highly recommend an enclosure or safety glasses too. Yes, the glass laser tubes are 'sealed' with the gas inside and not the type that need external laser gas (flowing gas lasers).

This is obviously based on you having an XY table with motion controller, and suitable software. Mach3, emc2, pic or something similar. You will need to have DAC or PWM control for the laser PSU too but that would be fairly simple if you already have the driver for CNC spindle etc.

Zax.

[methuso]

Zax:
thanks M8.
Yes i have a xytable, 2 setups of controllers to choose from and i am running EMC2 on a dedicated computer.
the DAC or PWM im not shure what You meen. i controll on and of of the diodlaser with a transistor right now. theres the PSUs on EBAY i am thinking about that has ttl or something..... i just assumed that i could send high or low directly too it *blush*

i am looking at the tubes+PSU kits that is on EBAY.

/Ulf

[zax15uk]

Ulf,

Yes you can use a high/low signal for basic on/off control, but pulsing the laser (Pulse Width Modulation) will yield better results as you get a higher power without the heating effect. It also eliminates the need to set power, since you are effectively controlling power with the switching frequency.

The ebay kits will be sufficient for engraving and cutting thin materials, probably up to 1/8" Acrylic without PWM. Using PWM you can easily do 1/4" at a slow speed.

Zax.

[TheMadEtcher]

Zax, you and I usually agree on stuff but I think you are being a bit conservative there. I would say "many" kilowatt. I'd say starting around 4,000W and close to 1/4Mil-dollars. :O

My company just bought a Mazak Hyper Gear 4000w and it cost just under 3/4 million. Cuts 1" steel .375" Stainless .5" Alum

[methuso]

thanks again Zax. Ill look into PWM then
/Ulf