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  1. Koether

    3A screws with 2A threads?

    Thanks for the input. That makes sense, it is odd that none of literature seems to acknowledge that the classes are or can be mixed.
  2. Koether

    3A screws with 2A threads?

    For some drawings that I have been revising I have been trying to get away from re-inventing the screw and am just referring to ASME B18.3 (SHCS) for screw dimensions and tolerances when I can. It was recently pointed out to me that ASME B18.3 requires the use of class 3A threads. This is a...
  3. Koether

    Flatness and parallelism

    where in Y14.5 is the discussion of the tangent modifier?
  4. Koether

    Flatness and parallelism

    Well the original drawings are from the 70s, they were updated at some point but no one really put any thought into the GD&T. These specifically call out Y14.7 (97) and the flatness I am referring to is total. Thanks for the feedback, it seems I came to the right place.
  5. Koether

    Flatness and parallelism

    Looking some of our old drawings I keep seeing surfaces with a parellel requirement along with a flatnessness requirement of the same magnitude. I was under the impression that parallelism already requires flatness to within the parallelism requirement, majking an additional flatness...
  6. Koether

    frequency of modes decrease with flow rate?

    The flow is introduced through a few inlets (in the radial direction, towards the center), the flow travels down to the bottom of the center piece which is only fixed at the top, above the inlets. The flow turn at the bottom and goes through a porous plate on the bottom of the center peice and...
  7. Koether

    frequency of modes decrease with flow rate?

    It seems like this effect you are referring to would only apply if you had an annulus that is close to a thin film, like in bearing. The annulus in this case is a few inches wide, with an ID close to 2 feet. The part is very stiff so the vibration shouldn't really have a noticeable effect on...
  8. Koether

    frequency of modes decrease with flow rate?

    I am working with a fairly involved flow induced vibration test. The main component of the structure involves a high fluid (water) velocity down through (not around) an annulus. One of the first things we are seeing in the data is that the first few modes seem to move down in frequency as flow...
  9. Koether

    Excel Curve Fit Coefficients

    I think I partly figured out what is going on, the macro that imports the data time stamps it, and with the excel time format I think it is causing some sort of overrun/rounding error. If I recalc the X values in terms of seconds from the first reading, (excel time format is decimal days.) I...
  10. Koether

    Excel Curve Fit Coefficients

    Having trouble getting this to work for a 3rd degree curve. It keeps wanting to make c3 = 0 and then c2 and c1 are equal to c1 and c2 from a 2nd degree regression. I've checked the formulas like 10x so that is not the problem. I'm using Excel 2003, not on a mac. any ideas? c3...
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