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LAN_403

Killa-X

Fri Jul 30 2010, 03:24AM

Registered Member #1643 Joined: Mon Aug 18 2008, 06:10PM
Location:
Posts: 1039

I've been working on a laser-CNC rig. Right now, it's going to start by being a laser engraver...Cut thin plastics...and etch decals into materials. It will start with using a 1W blue laser, and later be upgraded to a 60W CO2 laser I have access to. I've seen videos of custom made CNC machines with 40W CO2 lasers cutting 1/2" thick acrylic. I will be using my 60W for the same purpose, cutting detailed items out of acrylic, some thin woods, and other various materials.

I've only just started this project. So far, I got the motors to function properly. Saturday, I'll be picking up some wood/metal to begin the rig, and post pictures as I go. I plan to start with a simple pencil-drawer, purchase my 1W blue laser, and make it into the engraver. After a few months of having fun with it, and tuning it, I'll then slowly kick it over to a 60W CO2.

Until then, I bring you a test video!

http://www.youtube.com/watch?v=NVzMZ8zmtYo

The driver:

The steppers (NEMA-23)

The driver being used is the EasyDriver 4.3, which can be found for $15 at sparkfun.com. I had plans to make my own, but after reviewing the cost of materials, I found this driver a lot cheaper. It can work up to 30V, and it has current-limiting so I can keep my motors at a safe 700mA per phase. These motors again are NEMA-23. 24V 1.4A stepper motors rated 1.8 degrees per phase

Any questions, Please ask :)

...

Fri Jul 30 2010, 04:18AM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

Looks good, I am working with my roomate on a laser cutter (I have the 20w co2 and 100w nd:yag, he has the stages). I would be interested to hear if you have any issues and what kinds of solutions you came up for them, things like beam steering/shaping optics etc.

Adam Munich

Fri Jul 30 2010, 04:41AM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

You must post diagrams.

Killa-X

Fri Jul 30 2010, 06:25AM

Registered Member #1643 Joined: Mon Aug 18 2008, 06:10PM
Location:
Posts: 1039

Yeah, I have no plans to do the CO2 for a long time...Maybe not until next year. Right now my goal is to do a 1W blue for cutting thin plastics, and decaling. I know my source for a 60W cheap laser (know a guy) as for the PSU, I can either get it off ebay or custom. For cooling, laser coolers cost a ton...I might make a microccontroller peltier radiator. Use a thermo probe in the water and pwm the peltier to adjust the temperature...Else, go for more expensive.

Diagrams of what Grenadier? The circuits or the whole CNC?

As for the optics, Been looking around at different options. I might do a fiber link to the CNC, and leave the CO2 laser on the ground. then just adjust the optics to focus it. Have to see later, Been researching.

As for size, It's going on my desk. So I might aim for a 15-24". 24x24 table is the max I'll do, as I intended it to be a table-top CNC. Maybe in the future I can do a larger one if things work good.

Lethal Shot

Fri Jul 30 2010, 08:29AM

Registered Member #1623 Joined: Tue Aug 05 2008, 03:31PM
Location: The Netherlands
Posts: 39

Nice start, I'm working on a laser CNC too.
Your idea with fiber optics is not going to work for a CO2 laser.
At the moment no fiber optics exist that can trap and guide a 10,6Âµm laser beam.
For a CO2 laser the only solution is using mirrors.
For the cooling of the laser I'm going to use water cooling, because no matter which technique your using, the heat needs to be dissipated to the air eventually.
A peltier element only increases the amount of heat that needs to be removed, so I'm just going to use a large radiator with some fans.

rp181

Fri Jul 30 2010, 10:48AM

Registered Member #1062 Joined: Tue Oct 16 2007, 02:01AM
Location:
Posts: 1529

The 40W laser I use (commerical) is all air cooled, buy 4 or so 120mm fans. The head takes pressurized air, so air blows out the nozzle (I think its at 60 PSI) around where the laser is cutting. The whole thing has an exahust system.
The unit it designed to take up to 4 80W modules, all with air cooling, you may not need water.

Adam Munich

Fri Jul 30 2010, 02:22PM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

As far as I know, there is no flexible fiber capable of carrying 10640 laser light... Most everything is opaque at that wavelength. Only salt and zinc selenide are suitable for optics.

Killa-X

Fri Jul 30 2010, 04:21PM

Registered Member #1643 Joined: Mon Aug 18 2008, 06:10PM
Location:
Posts: 1039

Ah. Well a series of mirrors would work...to be able to take the beam around and through each axiz to a point where I want to cut material. The one I can get locally is like 40 inches long, so it would have to mount on the desk and mirror beam to the unit.

Only idea I had...Each axiz gets it's own mirror to hit the next

Adam Munich

Fri Jul 30 2010, 05:10PM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

That will be amazingly difficult to control. Also, be prepared for the ridiculous cost of CO2 laser mirrors.

Why not just use a 30 Watt 808nm diode bar coupled to a fibre. It would cost less, be a magnitude easier to control, and make more precise cuts. It won't cut clear acrylic though...

To make cuts in objects that deep, a CO2 laser will need to be focused into a thin beam, not a point. This will require both convex and concave lenses, and at ~50 bucks a pop (on ebay!), it's not going to be cheap.

The mirrors have to be perfectly aligned within microns with no jitter, else the laser beam will not be centered on the lenses. You will need active focusing because the laser diverges, and the machine will lose focus at the extreme axis-es [sp?].

You may be getting yourself in way over your head with this. With 40 watts of far IR laser, there is no room for mistake.

Lethal Shot

Fri Jul 30 2010, 07:35PM

Registered Member #1623 Joined: Tue Aug 05 2008, 03:31PM
Location: The Netherlands
Posts: 39

Well according to synrad a 60W CO2 laser could cut a 0,5" thick sheet of acrylic at a speed of 8,5" per minute.
Although without special optics you would get a somewhat rounded cut, but thats acceptable, definetly for a hobbist in my opinion.
And if he already has access to a CO2 laser the mirrors might be costly, but I think cheaper than a 30W laser diode bar (don't know prices of these things).

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