[Cathode]

My 60 watt laser tube and power supply for my homebrew CNC machine arrived today. I got it on ebay for under $1000 from what seemed to be a real nice operation. They were very helpful and fast to respond to my questions.

I couldn't wait to check it out. But, my worst fears came true. There are shards of glass floating around inside the outer tube. I heard them as soon as I picked it up. Nothing seems to be broken, untill you look really close. The outside tube is definetly cracked, but still intact. There is what looks like epoxy over the cracked area. It is still sticky. The shards look like they might have broken off from that area during shipping, or might have been left inside. The tube looks like it might work, since it is only the cooling jacket that is broken, until it springs a leak and floods my machine.

The seller said they tested the tube the day before shipping and that it is full power. I paid for shipping insurance. I've contacted the seller saying basically what I've said here, with the same photos and put a claim in with UPS. It will be instresting to see how this plays out.

I'm new with lasers. It that tube dead?

[Laser.Tech]

Sorry to see that, I put your build on my list of things to follow.

I've never ordered a sealed tube myself, but judging from a lot of these threads, yours is unfortunately not a rare situation. Do everything possible to get a replacement, or at least your money back. From your description it sure seems it started out broke and they tried to cover it up.(nuts)

If in the end you still have that garbage tube, it's possible it still works, just try it. It'll be a yes/no thing, either it works or not. But I sure wouldn't trust it in a machine for normal use.

Laser.Tech

[mactec54]

Hi Ricswika
UPS Did not put the epoxy on the tube The seller did that get it back to them
asap for a full refund was it packaged well as UPS will not pay a cent if the
packaging was poor and not up to the job of protecting the tube

[Cathode]

The seller already got back to me and said he will replace it. This is really good news.

It was shipped by the UPS store, so they can't say it wasn't packed properly. It was double boxed with a 2 inch peanut buffer. I doubt UPS looked at it as closely as I did, if at all, before packing. I really wonder what is going on here. I seriously doubt it got hurt during shipping. Maybe someone was hoping it would get totally smashed in shipping, and would collect on the the insurance. Maybe that is the angle. They will replace it and collect the insurance, thereby getting rid of a broken tube on UPS's and my expense. This is all speculation. Let's just assume it is an honest mistake, and the tube is really perfect. Maybe something stickly got on the tube, and the shards got washed inside from their cooling system during testing. It could happen.

I don't want this to put a damper on my enthusiasm for the project. This is just a bump in the road.

If anyone else has gone through this sort of problem, it would be interesting to hear what happened.

[ImanCarrot]

Man, that sucks, but I admire your determination dude. Hang in there

[MonoNeuron]

Hi,
Bad luck on that tube. I wish there were more success stories on these tubes than there are bad ones on this forum.
Just an aside note on the tube, if you look closely at it you will find 3 tubes with the inner one being the laser ionization tube then the middle one one about 1/4 inch away from the inner one is the coolant tube. The outside one is a storage container for more of the lasing gas and the coil of 1/4" glass tubing connecting the inner tube to the outer tube is there to prevent the gas from ionizing in the storage container. Very clever setup in my opinion.

I wish you well on you project and I hope I can post more pictures of my build soon as I am nearly finished with the mechanical and electronic side of it. Mad a few stuffups but thats all part of the fun working things out.

Rich.

[Cathode]

I should have a replacement tube by next week. Here’s a few questions about powering up my tube when it arrives:

1) Does it matter in which direction I run the coolant loop. Does it have to be in on anode and out on cathode?

2) What is a good operating temperature for the coolant. At what temperature does power start to drop off?

3) My laser tube is rated for 60 watts and has a 'matching' power supply. The tube runs at 16 kv and 20 ma, for a total power dissipation of 320 watts. By my calculations, I’ll have to dissipate 320-60=260 watts through the coolant loop to maintain a constant temperature. That’s an efficiency of 60/320, or about 18.75 %. I wasn’t expecting such a high efficiency. The question is, do these numbers seem realistic? If not, what is wrong?

4) How much water pressure can a sealed CO2 laser tube take? Mine is 1200mm in length. Does the tube have to be mounted level?

Thanks
Rick

[Laser.Tech]

Rick,
Here's my best answers...

1. Should'nt make any difference, assuming good flow...

2. This one is VERY important. Power will drop off rapidly as the temperature rises. This will start to occur immediately (long before the laser gets 'hot'). You want to run it as cool as possible BUT not lower than the dew point for your ambient conditions (condensation+laser=BAD!). I would suggest running it 5-10 degrees F above the dew point, or somewhere close between 65-75 degrees F. Because power is so sensitive to heat, a way to regulate (control) the temperature would be a good idea, rather than just 'keepin it cool'. And of course, an overtemp warning/interlock and flow switch are a must...

3. Your right on...(CO2s are typical 18-25% efficient).

4. No idea on pressure. But as long as there is no obstruction on the return line, and your not using a 10hp pump, can't imagine a problem...just don't hook it to the tap (city water services can hit 100psi here).
As far as mounting, I could be wrong, but I'm thinking vertical would not be a good idea. If there is any particulates at all in the tube, you know it will find it's way onto the bottom mirror eventually...

Hope this helps some.
Looking forward to more...
Brent

[coleong]

Some extra notes on the reply by laser tech,

water out is normally on the output side (High voltage side / output coupler side)

Normally the water is supplied by a cheap fish tank pump as the supplied water pressure is low.

water quality if possible distill water or RO water.

a water flow sensor is preferred to prevent laser "on" when water does not flow through.

[Cathode]

I've been looking for the right flow switch, but most of what I'm finding are expensive and really heavy duty. If you've got a part number or source for one that would help.

I found some nice flow indicators used on PC cooling systems, that have electronic output. I was thinking about making my own cut off circuit using one of them, as a last resort.

[Laser.Tech]

Here is a source for $29 flow switches, perfect for laser coolant loops. The item description even mentions "perfect for ...laser heads...":

http://www.surplussales.com/Switches/Flow.html

This is a surplus electronic/scientific supplier, so they may not have very many of them.
Get em' while they last! :wee:

Laser.Tech

[Cathode]

My replacement tube arrived today, one day early, and in a box that looked like it fell off of a roof or two on the way. Needless to say, there were a few tense moments while I scrambled to open the packages. As soon as I picked up the box I got a good vibe... probably because I couldn't feel or hear anything sloshing around inside like before. They had it double boxed, but they also put peanuts on the inside box this time. Plus everything was taped up a lot tighter that before.

To my delight, I could not find any damage. :banana: Hats off to my supplier for coming through. There are some water spots on the inside, probably from not using distilled water during testing, but otherwise it looks pristine.

Question: When I fire this thing up, will I see any light at all from inside the tube? I’ve got the IR safety glasses. I also have a Sony camcorder with night vision. I’m thinking I might be able to pick up the beam on it. I've also been saving some heat sensitive cash register receipts for testing.

I’m off to buy a 220 power cord and some tubing for my cooling loop. I could be firing it up later tonight or maybe tomorrow. (flame2)

[Laser.Tech]

Glad it worked out!

Yes, you will see the tube light up, kinda like a dim neon sign.

The only dangerous light output will be from the business end in the beam. Any kind of safety glasses will work (I prefer the fully enclosed kind for side protection myself). You don't need special 'IR' or 'laser' safety glasses with a CO2. The wavelength of the laser will not pass thru glass, plastic, water, or anything else you can commonly see thru (that's why optics are so expensive). Of course, it will BURN thru...

Which also means, night vision viewers and IR detectors will also not 'see' the beam (glass lenses). Putting something in the beam to burn will be your only indicator it is working. Havn't tried it myself, but thermal paper is supposed to be great for this.

Just remember, when you go to try it out, put something in front of it, or you might have a undesirable burn mark in your wall (or skin!). Bricks work great.

Brent

[Cathode]

My laser power supply is Chinese and the instructions are terrible. It almost looks like they used babble fish to translate it to English. I was able to figure out most the connections, but the AC hookup, of all things, still has me puzzled.

Here is what they say about connecting AC power:

"AC220V/50HZ – connect power to pins 1 and 4. Power supply is marked L for Line and N for Neutral.. Pins 2 and 3 are 220v output." (OUTPUT?)

I know I’ve got AC240v/60Hz, but this supply will still work with domestic 240V AC, according to the supplier.

Here is what the connector looks like:

1 L
2
3
4 N

But here’s what I’ve got on my 240 AC outlet.

L1 <-240V-> L2
L1 <-120V-> N,G <-120V-> L2

I’m assuming they mean hook it up like this:

1 - L1
4 - N
2,3 - L2 ???? (they must mean input)

Any help will be appreciated.

[jmg]

Hi Ricswika,

Do you have any of the mechanical part done for your cnc laser machine? (ie. table) If so would you consider posting pics? (unless I've missed them already somewhere on this site???)

Also, if you don't mind me asking...who did you use for a laser tube/power supplier?

Thanks,
jmg

[Cathode]

Hello jmg,

Good to hear from you. I haven't built the table yet. I am still debating the advantages of a flying optics design (mirros and alignement headaches) vs a moving XY table (wastes space, longer rails). I plan on starting a project log to discuss the pros and cons of each approach. I'll be posting pictures and sharing the process.

I picked up the 60 watt laser, mirrors and power supply in an ebay auction for just under $1000. I'm sort of taking a chance that it will work up to spec. I don't know where else you'll get near a 60 watt with supply for that price.

Are you thinking of putting your beak in?

Rick

[jmg]

Hi Rick,

Yes, I have my eye on a laser machine by www.emissiontechnologies.com as an alternative to building one. I would build but the only thing that stops me from building is the wiring. I'm not an electrician and the wiring of it all intimidates me. My strengths, if I can be so bold, would be in the table build along with steppers or servos and linear components. The software for driving the whole thing (table movement and laser firing is not a problem) but the interfacing of the laser to the computer as well as various input/outputs such as water flow sensor/on/off, home and limit switches, etc. don't come clear to my mind. I couldn't wire a breakout board because I don't know how.
Where are your strengths?

take care,
jmg

[Cathode]

Yes the emissions tech machine is one I've been studying closely. That machine made me think this was really possible.

I am an electrical engineer and software engineer. I'm used to interfacing PCs with all types of sensors and devices, and have built my share of robots and remote controlled vehicles. The mechnical engineering and fabrication aspects of this project are going to be the challenging parts for me. I have minimal metal working skills. My shop is set up for wood. I can't weld or bend sheet metal.

Even so, I have not doubt I can build this CNC machine, but the question is how safe, accurate and reliable will it be. My #1 goal is to not burn the house down.

You should take another look at how to wire a breakout box. It is really just connect the dots. Take one axis at a time, and break it down into the stepper motor driver and the limit switches. Look at the Mach 3 manual. They have some good diagrams.

[jmg]

Rick, I'm a Tool and Die Maker. I have a shop as well, only it's set up for metal. It's too bad we didn't live closer together...could've brainstormed a great machine I'm sure....

Thanks for the lead on Mach3 manual, re: diagrams, I'm going to have a good look. I knew that Mach was an excellent product but didn't realize diagrams existed. Thanks again.

I've included this link...for the machine you've been studying closely:

http://www.solustan.com/products/Co2Laser

enjoy,
jmg

[Cathode]

jmg

I'm in NE PA, Where abouts are you?

What kinds of materials do you want to cut?