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Old Jan 20, 2009, 03:21 AM
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what is wrong with a cnc router, and cut anything you wont
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Old Jan 20, 2009, 01:02 PM
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I'm with Tomi!

First ... to create an optics for a transmission of some Watts of laser light the material needs to be of the " advanced type...." no cheap polycarbonate " ... optical glass .. or in case of e.g. CO2 laser a Bronze mirror system.... --- This is NOT CHEAP

Next is safety ... would you cut material using an open unit where just 10% of the power of the beam reflected by a metal surface for a short moment and hitting you eye could make you bind????

Fast and professional lasersystems redirect the beam not via linear axis ... als long as you have ball screw axis - as long you are bound to the speed of them!!!
Call it "alternate plasma cutter" or "light mill" I prefere a CNC-mill I can see the mill; it won't fly cross the room blinding me... Ok it makes a bit noise but that is ok so I know that it is working!!!

Is good for metal ( .2842 Steel) is good for Auminium and is good for wood and you wouldn't have to get rid of dangerous fumes ( some plastics contain red Phospore and Halogene for flameprotection ( UL V0; V1) reacting to Phosphine and Halogen...carbonate ... HCl... when burned ...)

http://www.inchem.org/documents/icsc/icsc/eics0694.htm

Hansjoerg
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Old Aug 29, 2009, 12:05 AM
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I know this is kind of an old thread but I was searching around a found it and thought I would point out a few things.

YES, you can build your own, and relatively cheap if you look around.

High power CO2 laser DO NOT require BRONZE mirrors and lenses as suggested above. You can use pretty inexpensive gold plated mirrors and Gallium Arsenide lenses. You can even make your own mirrors out of copper disks by polishing them well, and they hold up great.

99% of laser cutting systems use a cheap to make belt transit system, NOT ball screws or any other screw for that matter. No screw would be fast enough.

Quote:
Next is safety ... would you cut material using an open unit where just 10% of the power of the beam reflected by a metal surface for a short moment and hitting you eye could make you bind????
CO2 lasers are among the safest "cutting" lasers to operate. Contrary to the above, the 10.6 micron wavelength of a typical CO2 laser cannot penetrate the eye, scattered reflections are highly unlikely to cause any damage to the eye. Normal acrylic/lexan safety glasses are all that is needed for CO2 operation. The HEAT is what to watch out for with CO2 as it it basically just a pure IR heat beam. A focused beam of a CO2 laser can BURN the eye, but light will not enter the eye, and a dispersed beam from even a pretty powerful CO2 would unlikely burn your eye, let alone 10% of it. Not that safety shouldn't be practiced however, meaning do not look directly into the beam.

You must keep in mind, cutting lasers use a focusing optic to focus the energy to a very small, very short beam that typically diverges VERY quickly. This is required for it to do any real work. A non focused beam can burn things and catch them on fire etc. but likely will not cut anything other than a piece of paper. This goes even for reasonably high power CO2 lasers in the 150w range.

I have a 150w Laser Engineering CO2 laser that I am making a table for. I have about $200 in the tube and supply off ebay with another $200 in enough mirrors and lenses to make the machine and maybe $200 in the electronics and mechanics and some scrounging.

Thats around $600.00 for a 150w 24x48in system.

Safety is important, but do not let someones uneducated ramblings deter you from such projects. A home built CO2 system is well within the realm of most with a little tinkering and common sense under their belt.

CNC routers are very usable as well,as stated above. Cheaper if you want to cut metals.
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Old Aug 29, 2009, 07:55 AM
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Originally Posted by RomeoRC
I don't think so and should say that it's very difficult. Purchase these cheap cutters.

I have used and had Demo'd a few of the Chinese laser cutters mentioned in Romeo's link. They ALL tend to work on a pulse system when the material gets thick or tough to cut. This then leads to a very wide kerf. Like a kerf you can easily see through.

The CNC systems, although they have some problems, do not have the big kerf to worry about then. And thus are less apt to excessivly wide kerf problems.

Solution? I was told by one laser dealer to simply cut some parts on desired material, then offset the position of the laser beam to result in a more appropriate part. Thus I need to create twice as many parts. Some on target, and others with a substantial offset to the centerline. And, if you need more than one set of parts, you get to do this all over again.

Wm.
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Old Aug 29, 2009, 06:02 PM
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http://www.iehk.net/Products/IE300.html

01.What is the maximum acceptable media thickness for ICut Cutter plotter?

0.8 mm (including backing paper)
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Old Aug 30, 2009, 08:54 AM
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Are you a member of the Yahoo group on DIY laser cutting?

Wm.
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Old Sep 04, 2009, 12:26 PM
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I have designed and used a CW 1500 w cutting system. Yes Gallium Arsenide lenses work great, the lower the radius number the closer to the lens you will focus. But remember, the air flow in front of the lens keeps the beam path free from out gassing which when the smoke interrupts the cutting beam, the cut will skip if you don't have enough power, jogging too fast, or your beam mode is off (more on this).
Typically an high pressure (~40-100 Psi) 3-4 mm air nozzle will be pointed at the work for outgassing, particulate control & cooling.

Safety;, never enough! Consider having a shutter that places a mirror into a beam dumping it into a stack of bricks in a bucket of water or something like an old kiln, so you don't have to turn the laser system on & off as you’re working. Everything should be anodized black if aluminum if it swings in & out of the beam surrounded by ¼ inch Plexiglas. Familiurize your self with laser material processing stations. These manufacturers change every year, but you may look up some of the greats such as “Spectra Physics and Coherent Inc” to see what kind of usefull add ons they brag about besides just the laser head itself. Beam dumps, shutters, power meters, alignment HeNe, air nozzles, work cubes, and by the way, plain drywall outperforms plywood in a ½ inch thick burn through test .

You should inspect your beam cross section with no lens. Place a piece of clear wood (far field mode test) in the beam path and expose it for a second or two. You are looking for a bulls eye pattern (He 11) or a solid (not over exposed) dot (He 00).
The health of the lens is important. Any little spec of dust or hot debris melted onto the extremely soft, plastic like Gallium Arsenide will start a fast downhill degrading of the lens and beam mode. The mode is a very important part of the cutting operation. You could check your beam profile (mode) with no lens, at say 20 feet away and see a quarter sized 1 second burned image that looks like a solid dot, light brown, not black (over exposed) and that would be perfect, or you could see a “target design”, circles getting smaller, maybe 4 or 5 of them. This shows beam cross sectional symmetry. Even try checking after the lens. 3-4 feet away to see how the lens has changed things. Plexiglas absorbs CO2 laser radiation (10.6u) and works for checking the mode also. If your mode looks like a face of a dude wearing a sombrero and has a long goatee, your mode is off, most likely caused by a dirty lens. You should have a protective window in front of the lens. A silicon wafer works best. Should be placed as close to the lens as possible to have the least watts per Cm
(power density), you don’t want to cut holes in your systems lens protection apparatus. You can have plenty of power, but poor cutting performance. Indicated by for example when you move in the X axis, and maybe ok in the Y axis. Spinning the lens 90 degrees and rechecking the mode will tell you if it is a lens issue or a laser mirror alignment issue. Power meter; you can use a thermocouple connected to a black piece of aluminum to check this. Read the millivolts with a voltmeter. The more voltage, the more power you have. But mode & placement of the beam spot will have a lot to do with the reading also. Adjustment of the laser mirrors (output coupler-front mirror) & the rear reflector change the output, mode, and angle of exit.

Is your CO2 laser water cooled? does it have a water flow interlock switch to turn it off as soon as the cooling water flow goes below a predetermined level? You should employ a key switch (electrical) to turn on the interlock protective system if you have others that could operate it when you’re away. Use of a Plexiglas box around your work (x-y table) platform will protect you from stray radiation. Talk about a heat lamp effect if you don’t. 150 watts is allot. Even 15 watts will cut your finger off if focused.

This is just a quick primer. Plain old plastic safety glasses should work as mentioned.
Remember, the best way to think about a CW (continuous wave) laser is comparing it to a “Machine Gun” firing continuously.

Please feel free to PM me and consult with myself privately. I have many years in the industry and hope to help. So how is it cutting?
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Old Nov 25, 2009, 05:15 PM
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I don't think so getting a laser engraver for 1k bucks will be that efficient,
may be its cheap but it has to be worth full.
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Old Dec 10, 2009, 01:27 PM
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Originally Posted by dpot View Post
what is wrong with a cnc router, and cut anything you wont
What CNC router are you using for those parts?
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Old Dec 10, 2009, 03:31 PM
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it is a home made router it has a 3 1/2 hp porter cabel 2m x 1m x 150mm and runs a hobby cnc setup

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Originally Posted by mt_100 View Post
What CNC router are you using for those parts?
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Old Dec 10, 2009, 03:41 PM
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Originally Posted by dpot View Post
what is wrong with a cnc router, and cut anything you wont
Well, I have cut items using CNC and often find that the part or slab of raw wood has to be elevated up some to allow for cutter clearance.

The laser often has a vacuum table to enable fast switchout of raw wood, such that you can then make parts fast as you can lay the new raw wood down and hit the GO button on the computer. With CNC you must "Clamp" down the part or it will get kicked around.

It is really difficult to get the CNC cutterto advance at same speed of a laser.

The cutter has a "direction" that needs to be set in via G-code or whatever is oerating the machine.

The cutter must be of minimum width, and via laser we can have one line cut for two parts. Cannot that with an end mill. In laser cutting we use .008" as a tolerance for the light beam.

We have a city-wide ordinace against laser cutting systems. And for CNC they say cannot be run after 6PM on any day. You are informed of this when you pull a Biz. license at City Hall.

Basically two different systems being mentioned.

Wm.
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Old Dec 11, 2009, 03:44 AM
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[quote=coosbaylumber;13788814]Well, I have cut items using CNC and often find that the part or slab of raw wood has to be elevated up some to allow for cutter clearance.

i use a sheet of mdf and when it gets cut up i replace it so the table is not damage


The laser often has a vacuum table to enable fast switchout of raw wood, such that you can then make parts fast as you can lay the new raw wood down and hit the GO button on the computer. With CNC you must "Clamp" down the part or it will get kicked around.

i use kebab sticks the cnc router drills 3mm holes and i fit pegs throw my material in to the fixing board and if the router hits one it just cuts throw it if you tap them in with a hammer they hold the part board down just great
cant afford a vac bed

It is really difficult to get the CNC cutter to advance at same speed of a laser.

with the new 36vdc board with match3 from 1500 units:min to 2500 units:min so i can travel from one end of my cnc 2m to the other end in about 30sec in alu a lot slower


The cutter has a "direction" that needs to be set in via G-code or whatever is oerating the machine.

not sour i writing gcod faster and spelt it right than i can write English or French but soft ware can do the job for you if you do not understand gcods


The cutter must be of minimum width, and via laser we can have one line cut for two parts. Cannot that with an end mill. In laser cutting we use .008" as a tolerance for the light beam.

i must admit cnc could not cut that small but can a laser pocket out a
mould or cut threads Male or female and under cut


We have a city-wide ordinace against laser cutting systems. And for CNC they say cannot be run after 6PM on any day. You are informed of this when you pull a Biz. license at City Hall.

this is a problem not for me as i live in the country but having said that i can start it running go flying and let it go and when i come back it has switch it self of when it is finished

Basically two different systems being mentioned.

as you say there is a place for both it depends on what you use it for and how much money you have to spend for my hobby useing the router give me more scope there are things that a laser can not do that a router can
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Old Dec 11, 2009, 08:22 AM
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Originally Posted by coosbaylumber View Post
We have a city-wide ordinace against laser cutting systems. And for CNC they say cannot be run after 6PM on any day. You are informed of this when you pull a Biz. license at City Hall.
Where is this? I've never heard of an odd law. Hell, around here mention you are starting a business and hiring and they bend the rules but that is the economy talking. Seriously though, noise, safety concerns, liability, what is their concern?

I work at a place running CNC and mills on 2" thick very hard wood and it rips through and cuts out a 4'x8' desk in a minute. Noisy but you can't hear is outside the building at all.
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Old Dec 11, 2009, 09:07 AM
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Our city incorporated a good 25 years ago (I wrote the deed at that time too).

Was a thing in local newspaper a good 10-15 years ago, that said need business license if you intend to do something at home, and made a big list of a few then. I went to city hall, and they handed me a five page list of rules and Non-conforming businesses, and then a one page list of OK. For grandfathering businesses, and another page of those subject to a secondary permit from Sacramento EPA. Laser cutting was there, and "Certain" machine shops depending upon if or not they were going to work with certain materials.

Each and every single business had to be shut down by 6PM each day. This applied to any home or office. Was one complaint that a trucking biz had ringing telephones well after they shut down, and they had to convert to some silent electronic answering service then.

May laugh now, but many of the California rules are coming your way now. Just wait. You may be dead at the time, the business grandfathered in, but the rules via whoever (In out case it was staff and the city council) will prevail.

I am having troubles in reading what DPOT wrote.

Wm.
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Old Dec 12, 2009, 03:42 AM
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I am sorry for the spelling I am a better engineer than a English teacher.

Je suis désolé pour les fautes, je suis mieux en tant qu'ingénieur qu'en tant que professeur d'Anglais.
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