[rutexus]

Hi Dave, and Cnc Construction,

Thank you again for sticking with me on this project. Guys like you, who are willing to give so much info are a real blessing to others.

Dave, I printed out the posts you sent to me on the links. Thank you for this info. They were thoughtful and I will read them again and consider.

Kern uses a metal laser tube, I think from the UK. They told me but I forget the manufacturer. Their cutting head costs around $12,000. Because of these factors, I have been reluctant to believe that a Reci laser tube would do the job, regardless of Reci claims. Kern also charges around $100k for their cutting bed. However, that tells me something about them too.

But I remember well how Apple computer got their little desktop pc's on the desks of fortune 500 company's purchasing agent's desks in the 1980's. So, I do not discount everything like this without checking first.

I do not really know what adaptive optics are, but maybe you are right. I have checked into collimnation, and I don't think that will be needed. Could you please send me a link so I can consider what adaptive optics are? Are adaptive optics another whole challenge? At some point the sheet metal application might just not be worth the trouble. That is a decision I am weighing.

Kern cut some samples out of 18 guage mild steel on their 150 watt laser and sent them to me. They were beautiful! I am amazed. That was before I started looking at their prices.

My son and I designed and built a CNC control that dropped the price on one application from $100K to $50k around ten years ago, so I know sometimes things are far overpriced. He runs the business now, and I am semi retired, and a laser cutter appears like it would be a great tool to have, and if I could cut 18 gauge parts for prototyping and custom parts, it would sure be handy. I mostly teach young people electronics and how to build things, so this application is a natural.

I have grasped that a 170 watt laser is no good for engraving. That is why I have planned to have two laser heads (one 170 watt, the other 60-80 watt). Maybe I can use an offset g-code to select the laser and head to use. The control is not the challenge at this time. I am considering your posts, and will wait to see what Melody says too.

Thanks again,

Tom

[Rodney Gold]

Ask for a sample of a cut piece of metal with a 150-170W reci....I would love to see the edge quality and the HAZ (heat affected zone)....

BTW running the RECI tubes at max power will severely shorten their lifespan , you can forget about 8000 hours , you might be lucky and get 800 hrs at 100% power all the time. Forget warrantees if you run at max power.

RF metal tubes (synrad and coherent etc) are not that reliable , we have had failures 300 hours on and some have gone on for 5+ yrs 8/24 - 5/7.

As to optics , buy only the best mirrors and lenses - they will cost round $4-500 , the lens is far more important than the mirror. For metal , I would never go for a 67.5mm lens with the low power you have available.

You would want a 1.5" lens (38.1mm) as it focuses on a MUCH smaller spot and has a far greater energy density (energy/cm2)..a beam expander/collimator wont harm either..the bigger the entrance beam to the lens , the smaller the spot.

If you want to cut metal , I would look at some of the chinese YAG's, When I was in china last , I saw 650W yags slice thu 10mm steel , these machines were in the $50k mark complete. Not sure what a 400-650W YAG power source will cost you , but its worth a look see...

At the end of it all , if you have a metal cutting job here and another job there, it might be a good option to farm it out..your 150-170W reci will limit your applications on your home built machine , all it will be good to do is cutting and very limited marking. You might find it a lot cheaper and more utilitarian to use something like an 80W reci or even a 60w cheapy on your build and outsource the odd "out of capability" job.

[Exsecratio]

Kern uses a metal laser tube, I think from the UK. They told me but I forget the manufacturer.

GSI by any chance Tom?

If so they are premium quality sources and reportedly the best available for low power lasers (under 1000 watts).

The introduction of Oxygen changes the entire ball game. All the laser is doing is heating the metal to red / white heat, it's the Oxygen doing the actual cutting in such cases all the beam is doing is instigating a reaction and not actually cutting the metal.

best wishes

Dave

ps:I'll dig out some info on adaptive optics for you .

[rutexus]

Hi Dave,

Don't bother looking up stuff for me on adaptive optics. I'm not going to get that deep into this. It has to be beyond my budget, based on the looking on the web that I did on that subject.

Rodney,

Thank you for taking the time to post. I just finished reading about your trip to China. What an experience!

Well, I have to admit, my enthusiasm for the metal cutting has surely been dampened. When I first considered a laser cutter, I was only interested in cutting 1/4 " plywood, and some acrylic. Maybe that is where I should re-focus. I'm sure it would have far fewer issues. I have to go teach now.

Tom

[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.