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CO2 laser.

Discussion in 'Laser Cutters' started by Tweakie, Feb 27, 2014.

  1. Tweakie

    Tweakie OpenBuilds Team
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    Tweakie published a new build:

    Read more about this build...
     
  2. JustinTime

    JustinTime Master
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    Tweakie, after seeing your build guess what I'm NOT going to do. Yeap, you guessed it, I'm not making a CO2 CNC laser. :( I'll stick to LED laser. Less complicated. :thumbsup::D
     
  3. Tweakie

    Tweakie OpenBuilds Team
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    :D:D:D

    I haven't even got to the complicated bit yet, but yes I agree this is not for everybody although there has got to be some other wacko's, like me, out there somewhere.

    :D:D:D

    Tweakie.
     
  4. Mark Carew

    Mark Carew OpenBuilds Team
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    Great build so far Tweakie! :thumbsup:
    I have a question about the un-focused beam length. After the first mirror running down the Y axis before hitting the second mirror. Does the length of that run have any effect on the power of the beam. Lets say you are etching a 4 foot board would the end closest to the tube have a darker burn because the beam is closer then when its at the far end of the run?
    What kind of power can you get with this size tube? What can you cut with it in comparison to say a diode laser.
    BTW that tube looks super scifi cool!
    Keep up the good work :)
     
  5. Tweakie

    Tweakie OpenBuilds Team
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    Hi Mark,

    Yes indeed sir, the total distance the beam has to travel does affect the power.

    In practical terms a variation in distance of 4’ or so will not produce any noticeable variation in power but if this distance is increased to say 8’ then it may start to show. For this reason the larger commercial machines (bed size 8’ x 4’) actually mount the laser tube ontop of the gantry so it travels with the Y axis then the beam distance variation is back to within the 4’ or so.

    I have no way of actually measuring my laser power at it’s smallest focussed point but, just as a guess, I would suspect it to be approaching a kilowatt.

    Things you can cut with a laser will depend on the laser beam’s wavelength.

    Just as an example the beam from a ‘visible beam’ laser will travel straight through clear Perspex, glass etc. whereas an Infrared laser (not visible) of the same wattage will cut into Perspex and etch the surface of glass.

    The cool looking tube was manufactured in the USA. Unfortunately, when it eventually reached the end of it’s useful life, it could not be replaced with like so I had to turn to a China manufactured tube instead – still looks cool though.


    Tweakie.
     
  6. Mark Carew

    Mark Carew OpenBuilds Team
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    Thanks for the information Tweakie, I have always wandered about the losing of power over distance on these tube lasers.
    So with your set up now, everything is in place that if you want to you could buy a larger tube and have a more powerful laser, say 40 kw 40 watts for cutting though ply, etc..?
    BTW I like the square tubing that you put around the beam on the new set of pics you added :thumbsup: great idea.
    Thanks again
     
  7. JustinTime

    JustinTime Master
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    40kw??? My dryer is 5kw. My stove, when all the plates and the oven are on at the same time, is 10kw and you want to make a home laser cutter at 40kw? Do they measure the kw differently in laser than in you stove, for example?

    BTW, 40kw at 220V, which is what we have in our houses' main service, is 200A.
     
  8. Tweakie

    Tweakie OpenBuilds Team
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    I have never actually seen a 40kW laser but I don’t think it would even go in through the door of my workshop. Perhaps best if I keep to 40Watts. :D

    Tweakie.
     
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  9. Michael

    Michael Veteran
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    Fantastic build! I have been looking at adding this capability to my CNC for quite some time(been a little hesitant of the Chinese laser tubes). I use a 120W CO2 laser at work frequently and it will cut through just about anything (only exception is metal). Love the tubing around the beam, I have seen quiet a few people forget where the beam is... not a pretty mistake

    Are you using any kind of flame suppression system on this build? Depending on the material you are cutting you may get flare ups that will cloud the lens (or start actual fires). Most commercial system use an air compressor to pump ~10psi out from a port near the lens. This seems to work pretty well for most materials -- still will get some flames with things like cardboard.

    Along the same lines some kind of smoke/fume extraction system will greatly increase the life of your lens/mirrors (not to mention keep the workshop smoke free)
     
  10. Mark Carew

    Mark Carew OpenBuilds Team
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    Whoops 40 kw 40 watts :rolleyes:
     
  11. Tweakie

    Tweakie OpenBuilds Team
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    Thanks Michael,
    Very valid points that you have mentioned, I think most of them will be covered as the build progresses but I just haven't had time to write it all up yet. Stay tuned folks :)

    Tweakie.
     
  12. Mark Carew

    Mark Carew OpenBuilds Team
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    Wait a minute I thought the test cut for Mach was the RoadRunner not Wile E :D
    Cool video Tweakie
    [​IMG]
     
  13. Tweakie

    Tweakie OpenBuilds Team
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    :D:D:D

    Tweakie.
     

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  14. JustinTime

    JustinTime Master
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    While smoke and/or flames is a valid point I never thought about it since I've haven't seen it mentioned anywhere. Will this be a problem with a diode laser like the blue 445? They are only a few watts but they still cut with heat. In foam and in plywood.
     
  15. Michael

    Michael Veteran
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    Tweakie: Very impressive etchings! what material are you etching on in those images?

    JustinTime: I haven't used the diode lasers specifically, but I would assume smoke/flame will still be an issue. In my experience foam and plywood cause a lot of smoke and ruin lenses very quickly. We cut foam shadows for a toolbox and ruined our focusing lens and final mirror while running an air assist and ventilation. However, routine cleaning goes a long way. Thor labs has a great optics cleaning tutorial (http://www.thorlabs.com/tutorials.cfm?tabID=26066), for most mounted optics it is easiest to go with the lens tissue and forceps method.
     
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  16. Tweakie

    Tweakie OpenBuilds Team
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    Chicken's egg shells :)

    Tweakie.
     
  17. JustinTime

    JustinTime Master
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    Thanks for the link, Michael.
     
  18. Mark Carew

    Mark Carew OpenBuilds Team
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    Nice job Tweakie! :thumbsup:
     
  19. Tweakie

    Tweakie OpenBuilds Team
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    Thanks Mark.

    Tweakie.
     
  20. Tweakie

    Tweakie OpenBuilds Team
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    Perhaps one of the greatest advantage in adding a CO2 laser is it’s ability to cut acrylic.


    Acrylic is one of those materials which will easily sublimate (change state from a solid to a gas without going through the liquid stage) and as a bonus, it also has the property to act as a waveguide at the 10.6 um wavelength of the laser beam. This enables acrylic up to 10mm thick to be cut with reasonably straight sides and have near perfectly polished edges which require no additional finishing.


    This Open Builds Logo keyfob took just 45 seconds to cut from 6mm Plexiglas and was made, just as an example, to illustrate laser cut acrylic.


    Tweakie.

    a1.jpg
     
  21. bobt

    bobt Veteran
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    Ok for all of you that are serious about a C02 lasers go to:

    http://www.buildlog.net/

    This is the site that is dedicated to building a DIY setup. It has references on how to, safety, sources for this.

    Bob Teeter
     
  22. JustinTime

    JustinTime Master
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    Is it, as in the case of acrylic, better to use CO2 because it's hotter that the blue led?
     
  23. Mark Carew

    Mark Carew OpenBuilds Team
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  24. Tweakie

    Tweakie OpenBuilds Team
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    Laser beams do not actually contain any heat, they are just a coherent stream of photons. It is the reaction of the molecules in the material laser beams come into contact with that generates the heat. :)

    Tweakie.
     
  25. Tweakie

    Tweakie OpenBuilds Team
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    These little bikes were laser cut some time ago and they are perhaps a good example of the edge finish that can be expected when working with acrylic. Unfortunately not all plastics behave the same way - with Polycarbonate, for example, it is doable but the edge finish is extremely poor in comparison.


    Exactly what a laser can and cannot do is to a large extent determined by its operating wavelength – for example my 40 Watt CO2 laser (operating a 10.6 um) will find almost all metals to be excellent reflectors, the laser beam just bounces off leaving the surface totally untouched. With different types of laser (YAG / Fibre etc.) operating at far shorter wavelengths the situation is entirely different and almost all metals are easily etched. So it is basically ‘horses for courses’ and a bit of trial and error soon reveals the strong and the weak points of any particular type of laser.


    Tweakie.

    a1.jpg
     
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  26. Mark Carew

    Mark Carew OpenBuilds Team
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    Nicely said, an I would add that this holds true for most if not all machines. :thumbsup:
     
  27. Manuel García

    Manuel García Well-Known
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    Hi, good job!

    I have a commercial CO2 laser (RF, not tube) and I invite you to use the following utility: https://www.facebook.com/CuttingBoxTool
    I tested it with acrylic and plywood and is awesome!

    Examples of use that I give to my laser:
    diseno_llavero_madera.jpg diseno_paraclub_galsur.jpg

    P.S.: Larger commercial machines use a beam expander that have two main purposes:
    - Increased power density in the focal point, (Without it, the thickness of the beam increases)
    - Beam guidance over long distances

    Regards!
     
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  28. Tweakie

    Tweakie OpenBuilds Team
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    Hi Manuel,

    Welcome to the forum, its very nice to see another CO2 laser user here. :thumbsup:

    Tweakie.
     
  29. Manuel García

    Manuel García Well-Known
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    Thanks Tweakie!

    We also have a galvanometric yag laser for engraving metallic and plastic things :rolleyes:
    I love this world!


    I am currently designing a DTG printer, to print t-shirts and rigid materials.
     
  30. Mark Carew

    Mark Carew OpenBuilds Team
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