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Thread: Galvo's

  1. #1
    Join Date
    Mar 2007
    Location
    Rotorua New Zealand
    Posts
    528

    Default Galvo's

    Some may have read my report on my recent idiotic test of whether a galvo mirror can stand being hit with a screwdriver... (the answer by the way is NO in a big way).
    This means of course I have to buy another and have that one fixed (back in China !!) in due course.

    That set me thinking there are a number of galvo options on the market. There is of course (and probably more).

    DT40- Pros - China
    The ones marketed by LaserShow parts - China
    The 6800 .. industry standard it would seem. - USA
    Eye magic - Europe
    Infinity
    etc etc

    I have been using so far (my only experience of galvos) the DT-40 Pros from Jian and at $550.00 US$ per set complete they seem to me to work well.... caution: I am no expert its just the sign above that says Senior Member.

    I know the LaserShowParts units are getting good recognition at around $850.00 Aus $. Bill from Pangolin has indicated he expects good things from them.

    Here is my question... what if any advantages are there in using one of the big names like the Cambridge 6800 or their higher speed version.
    These are in the $1700.00 US$ and up bracket, are they really that much "better" ?? and if so what is it that makes that so. Can you actually SEE the difference or is it in the engineering and longevity that it counts.

    One could say you could get three sets of the DT-40's ( or similar) for the money for one set of 6800's !!!

    Is this (6800) factually a much superior device or is it like owning a BMW or Mercedez its just neat to have one..

    What are your thoughts on this ?
    Does anyone have a set of 6800's and a set of Chinese "copies" to get a fair output and life test comparison ?

    Anyway appreciate your thoughts on this.

    Cheers

    Ray

    NZ

  2. #2
    Join Date
    Apr 2006
    Location
    Orlando, FL - USA
    Posts
    1,712

    Default

    Hi Ray,

    You may be able to fix your broken mirror problem very easily. Please post a picture, and then I will tell you what to do (or Buffo or Allthat will tell you my trick).

    Regarding your question, Cambridge scanners would definitely be better than any scanners not made in America. The reason is because Cambridge scanners (and other American companies) use Hybrid Ceramic/Steel ball bearings, whereas the non-American companies use all-steel bearings. Eventually the all-steel bearings will get crunchy, and then fail.

    Also, the Cambridge (and other American companies) scanners use US-sizes instead of metric sizes. This might not seem significant, but for example, the inside diameter on small American bearings is 2.4mm while that of metric bearings is 2.0mm. Since torsional stiffness goes as the fourth power of shaft diameter, the torsional stiffness of a Cambridge shaft is (2.4mm / 2.0mm) ^ 4 = more than twice as stiff as Chinese shaft. Also Cambridge mirrors are thicker, and thus stiffer than those of Chinese scanners.

    I keep saying non-American vs. American, not because I think American-made things are necessarily better, but because in this case, American-made has some unexpected benefits that might not apply to other products. The bearings are bigger, and hybrid bearings are not all that easy to come by outside of the US.

    There was one Chinese scanner company who recently asked me about the ability for them to acquire American bearings. Yes, this is possible, and if they do it, and change their shaft sizes too, then their scanners will be just as stiff and give the same lifetime as Cambridge scanners (when using Cambridge scanners with Pangolin LD2000 software, bearing lifetime will be essentially infinity, but that's a discussion for another post).

    Aside from bearing size and makeup, shaft size, and mirror size, Cambridge scanners would still be better because their position sensors are more sophisticated.

    Are Cambridge scanners worth the extra money? For true professionals, I would say unequivocally YES! but for hobbyists, the Chinese scanners seem to be just fine.

    Bill

  3. #3
    Join Date
    Jul 2005
    Location
    Lancashire UK
    Posts
    1,372

    Default

    Hi Ray ...

    one of the other things that Bill has mentioned in the past is that the Cambridge scanners coil is bonded in a different way to the copies, and is less prone to failing under hi heat conditions,

    I also guess that if you intend to do commercial shows and being paid at the end of the night requires a reliable show then its best to go down the Cambridge route

    Im not to far away from you today ..... just flown into Auckland New Zealand, Weds evening staying at Howick for a couple of days to see a customer then flying down to wellington to complete another job

    when i fly ill look out of the window to se if i can spot your plane buzzing around

    all the best .... Karl

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