Laser for CNC router?

This is the place for any magazine-related discussions that don't fit in any of the column discussion boards below.
Sterling Martin
Posts: 52
Joined: Wed Dec 15, 2004 1:01 am
Location: Missouri
Contact:

Laser for CNC router?

Post by Sterling Martin »

I'm debating whether or not to stick a laser on a CNC router that I've built. I would like a laser that would burn/cut wood. If it could engrave metal that would be nice also. There seems to be quite a few different kinds of lasers, and I am wondering what kind would be a good choice? Again, this machine would be mostly engraving, and not all that deep. Thanks, Sterling.
User avatar
jwax
Posts: 2234
Joined: Mon Feb 09, 2004 1:01 am
Location: NY
Contact:

Re: Laser for CNC router?

Post by jwax »

"stick a laser on"? You make it sound like you want to add a steering wheel cover to your car.
Lasers require training and are not cheap. Optics alone could cost as much as the laser itself. If you wish to proceed, you'll be looking for a carbon dioxide laser (CO2). Lots of forums on the net in their selection, use, and ah yes, maintenance.
John
WA2RBA
rshayes
Posts: 1286
Joined: Tue Mar 04, 2003 1:01 am
Contact:

Re: Laser for CNC router?

Post by rshayes »

If you want to burn wood, a CO2 laser is probably the best choice. Unlike most lasers, the efficiency is moderately high (probably well over 20 percent these days). Visible gas lasers tend to have efficiencies of a few percent.<p>There are several drawbacks to CO2 lasers. The wavelength is about 10.6 microns. Optics would have to be made of germanium or some more exotic material. This is expensive. The beam is invisible, and can reflect off of unexpectedly rough surfaces in unexpected directions. A 1/4 inch diameter, 200 watt beam can melt through a silica firebrick in about 10 minutes, leaving a glass lined hole.<p>Visible lasers can be more accurately focussed, but the power will be much lower, and so will the burning rate.<p>You may not be able to etch metal surfaces with any type of laser. Metals, especially with smooth surfaces, tend to reflect light rather than absorb it.<p>Any laser with high output is likely to be expensive and cost more than your CNC machine.
User avatar
Chris Smith
Posts: 4325
Joined: Tue Dec 04, 2001 1:01 am
Location: Bieber Ca.

Re: Laser for CNC router?

Post by Chris Smith »

A “Yag Type” [Artificial Ruby] pulsed laser will be the way to go, and its not cheap. <p>Expect to pay several thousand for a low wattage used one, and you will also need either a automated CNC or hand operated Milling machine base to control your work space. <p>Hand held lasers are never a great idea, unless you have a fiber optic connection.[mega bucks]<p>The Milling machine base will also will cost you any where from a grand, [used] to the "skies the limit" pricing for a CNC version? <p>The reason you need a Yag type pulsed laser.... <p>[Many types of pulsed lasers out there, Ruby, ND, Sapphire, etc] <p>.....is a CO2 laser is a constant beam, and with constant heat the wood or any cellulose materials will catch fire eventually. <p>The pulse type lasers super heat and then cool down between cycles and the burst of power also prevents over heating by blasting or vaporizing the material so fast, it doesn’t get time to heat up. <p>You end up "tattooing" the material.<p>I wrote this answer back about 8 years ago in NV forum about a guy who wanted to cut cloth [also Cellulose] with a laser. Same reasons apply.
Mike6158
Posts: 409
Joined: Fri Nov 12, 2004 1:01 am
Location: Weimar, Texas
Contact:

Re: Laser for CNC router?

Post by Mike6158 »

A friend of mine out in Lompoc, CA has a couple of CNC lathes in his garage. He designs and makes motorcycle parts. He also has a small Bridgeport mill. He does some pretty slick things with old silver coins too. Are you sure that you even need a lazer?<p>edit- The lathes are minitature lathes. Not hobbiest but not industrial. Hobbiest lathes use steppers to control the tool. His uses servo's.<p>[ December 24, 2004: Message edited by: NE5U ]</p>
"If the nucleus of a sodium atom were the size of a golf ball, the outermost electrons would lie 2 miles away. Atoms, like galaxies, are cathedrals of cavernous space. Matter is energy."
rshayes
Posts: 1286
Joined: Tue Mar 04, 2003 1:01 am
Contact:

Re: Laser for CNC router?

Post by rshayes »

Hughes Aircraft built a machine for cutting out garments in the early 1990's. It was an oversized X-Y plotter driven by a computer. It used a CO2 laser. It probably controlled the speed and used a shutter to avoid starting a fire. The idea was to stack up cloth about 2 inches deep and cut 40 or 50 pieces at a time.<p>I don't know what became of the idea. It may have been too expensive for the garment business.<p>Hello NE5U:<p>Small world, my father lives in Lompoc.
Mike6158
Posts: 409
Joined: Fri Nov 12, 2004 1:01 am
Location: Weimar, Texas
Contact:

Re: Laser for CNC router?

Post by Mike6158 »

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Small world, my father lives in Lompoc.<hr></blockquote><p>Well no kidding. I've only been there once. My son finished ALCM and CALCM tech school at Vandenburg and I went to see his graduation last month. Terry rides a Honda VTX as do I. That's how we "met". We have an annual ride to Denver every July. Oddly enough, in July, I probably didn't spend more than 5 minutes saying "howdy" to him. Another riding buddy (he lives up near San Franscisco) suggested that I give Terry a call and see his shop. I'm glad that I did :) <p>I liked Lompoc. In fact, once I got clear of LA, I liked California :) My only CA experience prior to this trip (I drove in from Texas) was flying into LA and working down on the docks of Long Beach many years ago so I wasn't REAL impressed with CA :) We drove up to the San Francisco area from Lompoc to visit my other buddy. Now that was a pretty drive.
"If the nucleus of a sodium atom were the size of a golf ball, the outermost electrons would lie 2 miles away. Atoms, like galaxies, are cathedrals of cavernous space. Matter is energy."
User avatar
Chris Smith
Posts: 4325
Joined: Tue Dec 04, 2001 1:01 am
Location: Bieber Ca.

Re: Laser for CNC router?

Post by Chris Smith »

Carbon Dioxide lasers are great, especially if you wish to cut 6 inches of cold steel, and better than a foot per minute with “laser accuracy”. However, CO2 lasers are bulky, expensive to run, and even more expensive to maintain. The optics for a CO2 laser are amongst the highest priced of any of the lasers, and the gas and cooling needs are troublesome, and the list is long. But, the CO2 laser is the king of the hill, when it comes to cutting. <p>Cheaper Yag types are only 15 to 18 inches long, require only a simple water cooling system and 120 or 240 volt house hold plugs can feed the power supply, and fitting the optics to CNC is relatively easy. <p>Lumonics is one company that can show you all the requirements that the Amateur or small business will need to get set up. Dollar for dollar and watt for watt, the pulsed lasers fits the majority of the small commercial needs. <p>And now, the Diode pumped laser arrays are entering the field and compete quite well with even the pulsed gas type lasers for reliability, size, and dollar cost.<p>[ December 25, 2004: Message edited by: Chris Smith ]</p>
User avatar
jwax
Posts: 2234
Joined: Mon Feb 09, 2004 1:01 am
Location: NY
Contact:

Re: Laser for CNC router?

Post by jwax »

I've engraved ("etched") with a LaserDyne 1,000 watt CO2 on steel, wood, and plastics. Closed gas CO2 lasers are available. Look for lasers on Ebay. They can be found cheap, but do everybody a favor and get some training first! An unexpected bounced beam off the workpiece will render you blind. Permanently.
CO2 lasers can operate pulsed or continuous. The HV to the cavity is simply pulsed.
In general, YAG's for welding, CO2's for cutting.
Safety always.
WA2RBA
User avatar
Chris Smith
Posts: 4325
Joined: Tue Dec 04, 2001 1:01 am
Location: Bieber Ca.

Re: Laser for CNC router?

Post by Chris Smith »

I think this web page describes the two, best. <p>**********************
What are the different uses for YAG and CO2 lasers? <p>YAG lasers and CO2 lasers react very differently on different materials because of the differing wavelengths of the laser beams. The wavelength of a YAG laser (1.064 microns) is exactly ten times smaller than the CO2 wavelength of 10.64 microns, which makes it ideally suited for absorption in most metals, but this small wavelength inhibits its ability to be absorbed by many other materials (wood, acrylic, plastics, fabrics, etc.) <p>[This prevents a fire from starting in wood, cloth etc]<p>A CO2 laser beam is not easily absorbed by metal, but can easily be absorbed by many organic materials such as wood, acrylic, rubber, etc, while it tends to reflect off of most metal surfaces. It's the different wavelengths of the two beams that are mainly responsible for the different types of materials that they will react with. There are a number of other differences between the two lasers; thermal efficiency, heat transfer, minimum and maximum power output, etc. and these characteristics all have an affect on the materials that the beams react with.

http://www.epiloglaser.com/tl_yaginfo.htm
bsparky
Posts: 84
Joined: Mon Aug 09, 2004 1:01 am
Location: Binghamton,NY
Contact:

Re: Laser for CNC router?

Post by bsparky »

Sterling was curious about your CNC machine. I am building one now my self. What did you use to drive your axis and what controls the machine.I am using steppers and a PC with software free from the WEB. I am thinking I will have to up grade my steppers though, will have to see when I get it all together.
Sterling Martin
Posts: 52
Joined: Wed Dec 15, 2004 1:01 am
Location: Missouri
Contact:

Re: Laser for CNC router?

Post by Sterling Martin »

Hi bsparky,
Yup, I'm using steppers also. I have found some rather large steppers on the black market (eBay) :-) I also think that it would be a lot better with servos, but steppers are a lot easier to impliment. I must confess that I'm not an expert when it comes to servos, so we went the stepper route. Maybe in the future we can upgrade to servos. Good luck!!
bsparky
Posts: 84
Joined: Mon Aug 09, 2004 1:01 am
Location: Binghamton,NY
Contact:

Re: Laser for CNC router?

Post by bsparky »

Sterling why do you feel servos would be better. I have many years experience with servos. There is alot more overhead using servos AC or DC. Feed back loop and velocity loop. I would imagine that servos would be smother thou. The software I have will handle 4 axis and uses G code.
Sterling Martin
Posts: 52
Joined: Wed Dec 15, 2004 1:01 am
Location: Missouri
Contact:

Re: Laser for CNC router?

Post by Sterling Martin »

Well bsparky, I don't have any real experience with servos, but I was always under the impression that they can be much more powerful than a stepper ( off the shelf parts ). Also the feedback would correct any error if you stalled. Technically, you could put a feedback system on a stepper, but if you go to all that bother, why not have a servo?
Tinkerer
Posts: 21
Joined: Sat Jan 08, 2005 1:01 am
Location: Pennsylvania
Contact:

Re: Laser for CNC router?

Post by Tinkerer »

I had a business running CNC CO2 lasers for several years, doing much like you want to do. I can tell you pretty much anything you want to know about 'em. There are small CO2 lasers available that are extreemly dependable and cheap to operate. If you just want to cut plastics, thin wood, leather and other non-metals, they are the way to go. I used a 30 watt laser to cut 1/4" thick materials and do engraving. There are some issues- as another poster stated CO2 lasers are infrared and are invisible requiring caution. It will also reflect off metals, so don't plan on doing much on them. The biggest problem will be the smoke and vapor produced by cutting- it will be nasty and there will be lots of it! You'll need a very good vacuum system to remove it while cutting. For small jobs a shopvac will do, but you need to route the exaust outside. You also need something to catch and absorb the beam energy that comes out of the bottom of the cut. My machines had a metal vacuum box with a honeycomb material. It held down the work, sucked out the vapors, and caught the unused energy safely. A single lens is all you need, and they can be had for under $100. Newer ones are self-cooling but older ones need a cooling system, basicly a pump and radiator. Use distilled water only! You'll need a low pressure air line feeding clean (filtered) air in front of the lens to keep it from being ruined by vapors from the cut. Used CO2s are out there if you do some hunting but you can still expect to pay several thousand bucks for one. If you haven't been scared off yet, drop me a line and I'll answer any questions!
Post Reply

Who is online

Users browsing this forum: No registered users and 31 guests