Faro Arm measuring - how costly?
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    Default Faro Arm measuring - how costly?

    I'm trying to understand how difficult it is to 'laser measure' something. I believe it's most commonly done using a Faro Arm, but could be wrong.


    In any case....in the sketch below, A and B represent the machined feet of a fabricated steel structure. I want to verify they have been machined properly....the spec requires they be on the same horizontal plane within .005".

    Assuming this structure is sitting indoors in a shop (in Minneapolis, MN) and the feet are accessible, is this a 'big' job? Who does this sort of work? etc.

    Thanks!foot-flatness-.jpg

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    While I don't know if Faro arms are made that size, I'll say that if you add up all of the different error sources on a Faro arm, they probably exceed 0.005". If you can get away with just flexing one, maybe two joints you'll be in better shape, but I'm still iffy on it.
    Tyrone described a leveling machine pads across long distances with a fluid level and drop indicators breaking surface tension a while ago, but I haven't been able to find the message this morning.

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    I don't have direct experience using a Faro arm, but my limited knowledge from a demo years ago squares with what jcca says; mainly that the error sources will likely exceed your tolerance. The larger the Faro arm is, the greater the accuracy tolerance spread. Much also depends on the person taking the points with the arm, as I have read (probably on this website as well). You may want to consider whether an alignment telescope and/or autocollimator with known-square return mirror could be used. The feet, if specified coplanar within .005, should be flat enough for a mirror base, I would think.

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    It seems like you could make a go-nogo gauge fairly easily ? Something like 1-2-3 blocks with a .005" hole through, parallel to one face (that's the hard part) then one of those cheapass surveyor laser transit type things people use to draw straight lines on the wall ? If the light goes through, then the feet are within .005. If not, not ?

    (I think I'd cheat and go with .007" - gonna be a bitch to get everything lined up perfectly, might want a bit of fudge factor.)

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    A follow-up for the OP:
    Portable CMM Arm Hexagon vs Faro

    This gives some opinions from a couple of years ago. It may be that the current Faro (or Romer/Hexagon competitor) has moved to laser scanning as a preferred mode of operation, rather than the manual probing I was remembering. In any case, it isn't cheap to buy one.

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    Quote Originally Posted by GregSY View Post
    I'm trying to understand how difficult it is to 'laser measure' something. I believe it's most commonly done using a Faro Arm, but could be wrong.


    In any case....in the sketch below, A and B represent the machined feet of a fabricated steel structure. I want to verify they have been machined properly....the spec requires they be on the same horizontal plane within .005".

    Assuming this structure is sitting indoors in a shop (in Minneapolis, MN) and the feet are accessible, is this a 'big' job? Who does this sort of work? etc.

    Thanks!foot-flatness-.jpg
    I use a FaroArm for inspection on our big assemblies. Depending on what CMM Software you have with it, you can use a feature called "leapfrog". Basically establish your Origin, then you need another point of reference that can be checked close to where your next inspection is. This allows you to physically move the FaroArm to a different location while maintaining your original Origin. Our FaroArm will reach 4ft radially.


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