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"Default" Math Vs "Legacy"?

Cumofogabriel
What are we calling the new default Geo-Tol math? "New Math"? "Default Math"?
I remember this gun fight a loooong time ago, it ended up bad for Hexagon and us also.
what I mean is:
The "New Math" best fits a little too aggressive for me compared to "Legacy". Last time I had reports coming out with perfect true position our customer Lockheed Martin mopped the floor with Pc-Dmis and started the whole ISO Best-Fit shootout, disallowing us to use Pc-Dmis best fit algorithms. The "New Math" best fits also. Here is a comparison:



What do you think?
and can we come up with a disparaging term like "New Math" other than "Geo-Tol"? or "Geo out-of Tol"?

thx
  • in reply to Ncogneto
    no, 3.6 was. it was SO bad...
    (how bad was it?)
    It was so bad that tech support told people to uninstall it and go back to 3.5
  • that's exactly what happened, we went back to 3.5 MR2.

  • in reply to Ncogneto
    of course, 3.5 had it's issue as well. When installed, did NOT TURN ON the table map by default, at least for the Sharpe32 controller, I don't know about any others. And, there was no documentation about this either. I had already stopped installing updates/upgrades until calibration time, if I had installed it at any other time, would have been royally FUBAR because of it.
  • in reply to SingularitY
    I was told MMC on threaded holes allows you to create a functional gage. I'm not a designer but I've heard that throughout my career.
  • in reply to cheesiechanman
    Theres very little if any satisfaction working in quality control
  • in reply to SingularitY
    Feature and Datum bonus both allow for easier design and use of a functional gage. On the CMM, bonus doesn't do much unless the customer states position is of the minor diameter. Otherwise, it's my understanding that the pitch diameter is what should be used to calculate bonus. I'd be surprised to see the CMM picking this up.
  • Dear Illustrious Programmers and other lecherous Forum Members,


    I sincerely appreciate ALL the inputs to this conversation, while emotional and overdramatic, empirical and mildly dramatic and threatening: (Oooo000000000000000ooohh Nooooooooo000000000000000000, I LUUUUUUUUUUUUUUUUUUV drama!) I really feel we've popped the cherry on this topic, and before you all kick me out of bed, I'd like to ask one more question of us.

    I am mildly enamored with the "newmath" unrelated actual mating envelope (UAME) and the local and global Least Squares Algorithms, I empirically repair to least squares because in my understanding, we can only with any certainty mathematically deduce the middle of something and that's it. But, I work for a living, and I'm only as valuable as I can be accurate in my measurements period. Nobody pays me *** for guessing.
    i've tried my hardest to understand the gobbly-gook here:

    https://docs.hexagonmi.com/pcdmis/2020.2/en/helpcenter/mergedProjects/core/geometric_tolerances/Evaluating_Size_with_the_Geometric_Tolerance_Command.htm

    But I want to know from the guys who somehow survive this mess day in and day out:

    How do you use these options when probing diameters over 1.0000 with tolerances below .0005 total on global machines?
    What combinations do you use to homogenize and harmonize UAME, LS Local Size without datum shift to give clear, concise and stable direction to machine correction and set-ups?

    Off-topic:
    (I woke up this morning wearing all my clothes from yesterday except for my shirt, my girlfriend woke me up and said: "Baby, you need to get to work now, you're late." I asked her: "What happened, what did I do last night?" and with a far away glassy eyed stare and a smile she said: "I'll tell you later." Wink

    Sincerely,

    SPace-Cowboy
    Gabriel
  • in reply to Cumofogabriel
    With a total tolerance of 0.0005", there are so many variables you need to isolate:

    -Environmental: Temperature of the room, Temperature of the part, Temperature of the part after you handled it.
    -Machine's physical limits: Linear/volumetric reproducibility, probe sensor's reproducibility,
    -Fixture/setup bias: datuming strategy, your routine's ability to isolate part/fixture interaction, number of hits/scanning spacing (if available) and where hits are locating relative to manufacturing process, how part is being restrained on machine.
    -FOD (oils on your hand transferring to the parts, debris on the probe, debris on the part sample)

    Looking at your profile, an old Global performance silver with a massive 20-40-20 size simply -might not be accurate enough- to discern pass/fail to this tight of a tolerance. You need to assess your gage's capabilities via MSA to accurately validate its' fitness for the task.
  • in reply to bfire85
    If you're masochistic the coordinate values listed is post transformation, you can get an idea of what has been done by comparing to nominals.
  • in reply to vpt.se
    Yeah, I had a profile of surface best fit several cm away from the part. I only noticed because I built geometry from the coordinate data listed in the FCF.
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