Smallest CO2 you've seen?

[Kmor2004]

I was wondering what the lowest power or smallest CO2 laser anyone has seen in person running, or seen online, also if you can remember how many watts it produced.

I'm just askign because I'm realy interested in trying to make a homemade CNC laser machine possibly using galvo-scanners and I'm thinking a 5-10W CO2, since I'd like to be able to cut, engrave, etch light metals and acrylics of various colors and tints, but the lowest I can find online atm is a 25W and I believe a few years ago I read on another forum where a guy managed to get a 2W or a 5W laser.

Sure a 25W or higher would let me do more and get it done faster but I'm not too keen on having a 2ft-6ft glass tube running at ~15KV, I'd be much happier with a laser in the sub 15" region even though it probably would be lower power and take longer to cut or engrave stuff with I could have a better chance of not blasting through the copper and the fiberglass if i tried to use it to make pcbs.

 

[Flaminpyro]

Do you know if you get a 25 watt tube you can run it at 5 watts.
the machine I use has a 15 watt tube in it and sometimes it's pretty hard to engrave certain metals. we have to paint them black so the laser can etch them.

 

[Things]

I believe the smallest CO2 tubes would be the RF excited ones. They do around 10 watts and are pretty small

May I ask why you want to use a galvo based system? Keeping the focal point right using galvo's is difficult, and may scan too fast to etch with only a few watts.

 

[Kmor2004]

I was thinkinf a galvo system so that the laser body would stay stationary, and I wouldn't have to source out sleds big enough for the 12"x12" max board size I'd like to use, nor stepper motors, or stepper motor drivers, as well as the drive mechanism.

I could just use a 100mw laser persay aim it at the galvos run it for a little bit to see where I have to place the galvo unit to get the full area, decide what orientation I want either have the galvo unit projecting like and actual projector onto the target, or have it aiming down, then get the laser beam to the galvos, and focused to as close to the size of beam that I want with even coverage, considering from one point to another the focal point will most likely be different, while a few spots would have the same focal point, then the rest is just in software control of laser pulses, and location of the beam.

Is it more complicated then that, oh yes it is, but thats just the summary of my idea, and quiet posibly standard galvos may not work as you pointed out, so I may end up making my have to make my own sudo galvo, probably using hobby servos and propper mirrors to adjust the angle and location of of the beam, and with as slow as the servos would be might also be able to through in a custom focusing lens mount that could be incremented and tracked to maintain an even beam size. :evil:

Thanks for making me think about that a little bit more.

 

[DashApple]

Smallest ive seen was a 7 watt HV driven one that was 35cm Long , i guess you could get samller , be cool to get a custom made 15cm long one xD If possible , Would be cute Lol

 

[millirad]

At the low end of power, a CO2 won't make you happy if you are going to scan the beam. Just not a lot of power onto the target. A 10W CO2 is a relatively weak laser for industrial use, unless you are working with some thin black/dark plastic. It is a good project though if you don't scan the beam, so don't let that stop you. You can always x/y the piece being worked.

 

[Asherz]

Like milirad was saying, have the platform holding the piece your going to etch move instead of the laser head, that way you can have it stationary above and just have the platform move x/y.

 

[Kmor2004]

Really that much power is lost from bouncing the beam off a few mirrors?

Also what determines the power of the CO2 laser is it the current or the tubes length, something else or a combination?

 

[chipdouglas]

its not so much that power is lost... its the focal point that is constantly changin. you pretty much need a fixed focal point

michael

 

[Alexizupinhea]

Regardless of what type of system you use, I believe you would still need a focusing mirror/lens of some sort because the factory beam specs of the tube would be at some arbitrary point far away. I could however be wrong with this statement, as I don't have too much experience with them. I only recently purchased a 25W CO2 tube w/ power supply and a ZnSe focusing lens, but haven't had the courage to turn the thing on yet.

Really that much power is lost from bouncing the beam off a few mirrors?

Also what determines the power of the CO2 laser is it the current or the tubes length, something else or a combination?

As mentioned, the focal point is what truly matters. If you are trying to engrave, the focus should be at the surface of the material. If you are trying to cut, the focus should be at the bottom of the material (surface of the table). Of course, more sophisticated systems may be able to have a z-axis which would scan the focus point quickly from the top to the bottom of the material - I believe this process has a name, though I don't remember it.

To develop this statement about the focus even further, what is important about cutting or engraving is not simply power, but rather intensity. Intensity is power per unit area (I = P/A). This is why lasers are so dangerous, the power 10mW doesn't sound like much, but the fact that it is all focused to a point of maybe a few mm's which makes the intensity jump to millions of Watts per square meter (since A=pi r^2 and r is in milli units). Therefore, when the spot size increases from say 2mm to 10mm if it is not in focus, the intensity of a 25W beam would jump from 7.96 * 10^6 W/m^2 to 3.18*10^5 W/m^2. That is 25 times less the intensity, therefore greatly changes the cutting/engraving power of the system.

And yes, what determines the max power of a CO2 laser is basically the tube length. You can vary the current going to the laser in order to decrease the power, but ultimately tube length plays the limiting factor in terms of max power. If you are interested in more info about CO2 lasers, Sam's Laser FAQ is a tremendously valuable resource. http://repairfaq.cis.upenn.edu/sam/laserco2.htm You should probably start at the "Basic Principles of Operation" section.

 

[LSRFAQ]

Galvo driven CO2 systems use a "F-Theta" lens to correct for the changing focal point. Either that or a galvo driven focus stage. Neither is cheap or common.

I placed a CO2 F-Theta on ebay at my last employer. No one even wanted it.
Same for the galvo driven focus stage, which btw, is slow, ie G330 driven.
I'm sure the auctions were pulled and the stuff was scrapped after I left.

I'd suggest a X-Y stage. You will be happier.

I would also suggest that you price the difference between a compact RF excited waveguide tube and a higher power wide bore. If you can find a Synrad compact head, you may be happy. However, a 10 watt Synrad is 3K$ new.

Steve

 

[Kmor2004]

Pardon my ignorance but by X-Y stage I presume you guys are refering to the actual table moving or a structure that moves in the x-y directions over top the target material.

At this point I guess I should ask roughly which would be ess expensive buying a 25W or making a 25W CO2 laser?

 

[millirad]

This ebay 25 watt auction might be cheaper.........................

NEW 25W CO2 LASER TUBE + POWER SUPPLY NO RESERVE | eBay

 

[Kmor2004]

Had a feeling, I've been watching most of the auctions by that guy the last 25w ended on tue at 152.86 + 40 s/h, hoping I can score this one or the others for sub 100 or right at $100 after s/h.

 

[james1095]

The smallest I've seen was a cool 10W self contained unit that looked a lot like the educational HeNe lasers. Black brick about 18" long, this was years ago and I have no recollection of who made it but it was a neat little unit.

As others have said, you will want more power for CNC work. Easiest way is probably to move the table in one axis and have the optics on a gantry that moves the other axis. You could also look at the Chinese laser cutters and build something similar.

 

[chipdouglas]

Pardon my ignorance but by X-Y stage I presume you guys are refering to the actual table moving or a structure that moves in the x-y directions over top the target material.

At this point I guess I should ask roughly which would be ess expensive buying a 25W or making a 25W CO2 laser?

correct. and good luck with your project. If you do actually do it make sure to post pix and vid!!!


michael.