A CO2 laser is most commonly used for wood cutting and decorating.

    We suggest that minimum 100 watts be considered, certainly no less than 25.

    A used machine may not really be the best. In the last year or so, sealed-off lasers in the 100 watt range have become available with lifetimes of approx 10,000 hours. If you go with a used laser that has to be pumped down and supplied with CO2, N2, and He then you get into a lot of auxiliary equipment that will be priced in addition to the cost of the bare laser. Additionally, the size of the used laser, power supply, etc will be huge compared to a new one which will be compact and light.

    Then consider moving the laser head itself around under computer control to do the wood burning. With a larger used laser, will need additional beam-delivery optics that are also expensive and will require extremely critical alignment.

    Another thing that must be considered. The laser itself will have a beam that may be around 1/4 to 1/8 inch diameter. To get to the tiny, hot spot that will do the cutting, you use a lense to focus the energy. But the smoke from the burning wood will ruin the lense in a few seconds so it has to be encased in pressurized chamber with a tiny exit hole that blows a compressed gas out the same hole the nearly focused beam emerges from...thus keeping the smoke away from the lense. The depth of focus is small if you use a short focal-length lense and the power density is not as high if you use a long focal-length lense. So you may need to use the applications department of your supplier to help you with your first machine. Or work with someone who has an existing machine and learn everything about it before you undertake to build a system from scratch.

    Industrial lasers up to 2kW are used effectively in cutting wood to 3 inches thickness in the furniture business. Steel-rule dies are cut up to one inch thick with 2kW lasers in very common use. Shop air - clean and dry is used as an assist gas in all of those examples. The edge produced is square, with a dark grey to black color and the carbon is 0.005-0.010" thick and easily removed with a sandpaper rub. Using nitrogen as an assist gas would clean the surface a little but would be expensive.

    Usefull wattage for cutting metal would typically be at a minimum of approximately 400 watts of CO2 laser power. A simple slow-flow design could be managed by someone with good mechanical skills. The cost would be equal between the resonator structure, power supply and optics. You would most likely want to have at least a 100 ma power supply. The laser gas could be obtained easily enough in a pre-mix format from an industrial gas supplier. The driving question is this; is this laser to be used in any sort of continuous manner, such as production. The cost of doing this in the basement could easily run several thousand dollars. This is probably still cheaper than buying a used laser, but then again, buying a used laser will normally get you a working and ready to go unit.