[rutexus]

Gentlemen,

I am slowly building my first laser machine. I want to cut thin mild steel 18 ga sheet metal for our company. I am still working on the XY table at this point, but am planning for the optics now. Someone posted that the typical gold plated Si mirrors have an 80 Watt max power rating. I wondered about that.

Three different Chinese distributors of the Reci W8 170 Watt laser tubes will sell me the laser tubes, but admit that they have no experience with specifying the optics. Neither can they specify the appropriate focal length for the lens.

Will I need to use some other type of mirrors and lenses to handle this kind of power?

Will they need to be water cooled?

Can anyone estimate the appropriate focal lens for this application?

Thanks,

Tom Eldredge

[cinematic2]

Is thnat a joke?
Who told you to use Reci to cut steel?

[Exsecratio]

Hi Tom,

a 170 watt tube is going to do a terrible job of cutting steel shim let alone 18Ga steel

Fiber would be the way to go possibly but that gets expensive.
You would do better to get a real metal cutting laser from Mazak or suchlike, expensive but at least they cut properly.

best wishes

Dave

[Melody-gweike]

Hi, Tom,

It is possible but it has high demand for setting up skill and machine parts.

We have a similar machine as what you are buiding for cutting metal. But only for within 1.5-2 mm thick steel and stainless steel. If you want to cut metal, your machines must reach following demands:

1. high power steady Co2 tube
2. Servo Motor and Ball Screw to get higher cutting ability
3. Very good quality mirriors and lens. And they need water cooled.
4. With the help of Oxygen
5. The beam alignment must be very accuracte
6. Focial length, common 63.5 is OK.


------
Melody
[email protected] [email protected]
skype: melody.gweike

[Exsecratio]

I'm not a fan of budget Oxygen assisted lasers at all if you don't have your game face on and something goes wrong they can relocate your building and anybody in it.

It's one area of the laser cutting industry where saving money can genuinely cost lives.

best wishes

Dave

[rutexus]

Hi Dave,

I appreciate your comments. Could you be more specific on the issues that one needs to be careful with in using oxygen as an assist.

We do not plan to do this on a production basis, only a job here and there. As it seems to me, some of the O2 would be burned, and some would not. If the machine has a strong forced air draft above and below the sheet metal it seems that the little bit of O2 that would remain would be pretty well diluted. What other concerns are there. I'm not tying to be smart in this response. I really want to know.

Tom

[rutexus]

[QUOTE=Melody-gweike;1230776]"
Hi, Tom,
It is possible but it has high demand for setting up skill and machine parts."

Hi Melody,

Thank you for your thoughtful response. I would like to ask you some more specific details, that others might also want to know.

The price of Fiber laser is out of the question. Kern Laser, in the USA, sells a 150 watt CO2 machine that cuts 18 guage steel sheet metal. I figured I could maybe get it done with the 170 Watt Reci tubes. Kern uses a metal laser tube. I have asked a couple of people what is the real truth behind the "metal/glass laser tube debate" and sometimes they chuckle first, then they seem to indicate that it is mostly hype. I don't really know. The price of a metal CO2 will also probably knock out this idea for the present time, so I want to hear what Melody says about that.

Melody, does the machine that you make and you refer to have a metal laser tube? Does the Reci W8 tube not have a "stable" enough output to do this?

I am using belt drive, with servo motors and a 10:1 gear reducer on each servo motor, so I am thinking that my motion should be smooth enough for laser cutting steel, and I do not need the torque supplied by ball screws. Please comment.

Can your company supply appropriate mirrors and lenses, and do you water cool them with coolers mounted on the back side of the mirror?

How about the lens? Does it need to be water cooled? Are there fixtures available to hold the lens and sufficiently cool it too? Can your company supply them?

I am hoping that I can use care and align the optics. I have been looking at tips supplied by various users on You tubes to see different methods of aligning them.

I have a capacitive torch height control that I can use to keep the proper distance of the laser head from the sheet metal.

I have asked Dave, who commented that Oxygen assisted cutting laser is dangerous to please provide more details of how to insure safety.

I have posted my request on Alibaba for suppliers of lenses and mirrors for this application, and received a number of responses, but I do not know who to trust, as they just say they can supply them and give me a price. I want to be a more informed buyer than this.

The fact that Melody has provided this much detail makes me more interested in looking to them as the supplier of choice, so I hope to hear more from her.

Actually, I am planning to build my machine with two laser heads: both an 80 watt laser tube for engraving and cutting acrylic and thin wood, and the same xy table and a different set of optics and laser tube to do the sheet metal cutting and the higher power coming to the laser head from the opposite direction. For the sheet metal cutting I would use Mach3 or Mach4 (we are an OEM and Mach4 will be available very soon.) For the engraver, we will probably use one of the aftermarket raster circuit boards referred to in other parts of this forum.

I would think others would be interested in cutting steel sheet metal, so I hope to hear more from Melody.

[cinematic2]

"Metal" lasers are RF excited.
"Glass" lasers are DC excited.
Difference is like a pony and horse.

[muqtadir]

What is the best RECI tube's watt. (100, 150 or 200 or ???) for metal engraving or marking close to YAG marking ?

[Exsecratio]

None of them, the Yag system is usually a galvo and runs at 12 to 20 times the speed of a gantry laser.
The spot size of the bigger tubes makes definition a problem and running the tubes at full wack to get them to mark metal will shorten their life by a fair sized amount.

best wishes

Dave

[Melody-gweike]

Hi, Tom,

Sorry for late reply for your e-mail. We are having our holiday for new year.
It is not easy work while it seems you have started.