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IndustryArena Forum > CAD Software > Alibre Design > Finding Center of Mass (COM)
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  1. #1
    Join Date
    Jun 2012

    Finding Center of Mass (COM)

    To simplify what I'm trying to do, I've drawn a 4 inch circle with a thickness of 0.25 inch. When I analyze the physical properties of the part, the center of mass is not 0,0,0. I'm sure it's a user issue, but I'm not sure what I'm doing wrong. Any suggestions?

  2. #2
    Gold Member
    Join Date
    Jun 2006
    Looks like center of mass is X = ~10-16 (darn close to zero), Y = 0 and Z = 0.125. Since you have the floor of your disk at z=0, and the disk is 0.25" thick, the center of the disk in Z would be at 1/2 x 0.25 or 0.125" Therefore, COM = 10-16, 0, 0.125 seems pretty close to reality to me.

    Does that help?


  3. #3
    Join Date
    Nov 2010
    I was going to blame pi and rounding error as this was a cylinder, but I get the same "non-zero" with any other shape. Though, as was already pointed out, 8 x 10^-17 is certainly close enough to 0 to call it zero. I suspect it is just leftover rounding error that should not be getting reported...

    I played with decimal places, precision, etc... but you can only set up to 6 places, and what this is reporting is 12 or more decimal places.

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