"Default" Math Vs "Legacy"?

In my experience, having corrected probably more than a thousand errors in PC-DMIS programs, most programmers don't understand the math well enough to make correct programs. Having the software limit options so that it is easier to do right is generally a good idea. You can always use legacy if you need a better idea of what's happening yourself.

Yes, I agree very much so. Therefore we are abandoning the use of the CMM for size of the feature, but we still are concerned with the location of the feature. We are assuming default math makes a maximum inscribed feature, then details the centroid of that. what I'd like to see is more of a Zeiss style construction, which like recompensate, tosses out the probe diameter, locates the centroid, performs a roundness function mathematically filtering around 3 sigma, locates the centroid, then passes the probe diameter through for probe comp.

Machine's uncertainty limitations pertain to both location and size.
If your location tolerance is similar to your size tolerance, you are still using the wrong tool for the job. Unless you shore up all potential contributions of variation as best you can, and prove that variation is reproducible via MSA to a level your organization/customer expects... You are sh!t outta luck in measuring this part on the cmm.

Default PCDMIS math is Best Fit (BF) least squares methodology (judged with by all hits having the same "weight").
You can toggle ASME and ISO in settings for each routine, or with "UseISOCalcualtions" toggle in settings editor.

You surely know you can alter the strategy of each feature at will.
BF (LSQ), MAX_INSC, MIN_CIRCSC, MIN_SEP, FIDED_RAD, and BF RECOMP (which is tossing probe dia and putting it back in),

Dear Furry Members,

I just cant buy in. I've dipped my toe in the Default Math water, and I'm gonna sit this one out. I just don't see enough correlation when mechanically I can't validate its output. Just instinctively at a gut level, I don't feel confident at all passing any information gained by these new evaluations to the machine shop. I have tried, and in the end I felt I looked foolish and incompetent. The new information derived produced no benefit to manufacturing, and just muddied up unclear directions even more. I don't get paid to guess, and I really feel this is another best guess by hexagon.
Sorry Neil, I don't mean to make this personal, but you are the product owner, and I know you will.
I'm NOT diving in the "Default Math" pool, I'll be here in the cabana , enjoying some drink with an umbrella or something.

CHeers.

Dear Furry Members,

I just cant buy in. I've dipped my toe in the Default Math water, and I'm gonna sit this one out. I just don't see enough correlation when mechanically I can't validate its output. Just instinctively at a gut level, I don't feel confident at all passing any information gained by these new evaluations to the machine shop. I have tried, and in the end I felt I looked foolish and incompetent. The new information derived produced no benefit to manufacturing, and just muddied up unclear directions even more. I don't get paid to guess, and I really feel this is another best guess by hexagon.
Sorry Neil, I don't mean to make this personal, but you are the product owner, and I know you will.
I'm NOT diving in the "Default Math" pool, I'll be here in the cabana , enjoying some drink with an umbrella or something.

CHeers.

.......................................

It seems like the "I can't validate its output" is a function of your level of experience and knowledge.
You don't use your gut to validate confidence in a process, you use math.

for the record, Calypso's strategies are still an averaging estimation of the data hits, just like PCDMIS's options. it's simply a different software.
In fact, calypso's default strategy is also least squares. it's industry standard to use the median output of hit point variation.
https://carl-zeiss-industrial-metrology-llc.helpjuice.com/en_US/calypso/algorithms

I will absolutely agree that PCDMIS's Gaussian and hit-filtering strategies are garbage, and historically useless... but they have been working on improving this function.

In any case, you can extrapolate hit data and use excel, matlab, minitab etc software to help you determine if the PCDMIS strategies are correct.

neil.challinor
is it possible to incorporate the "like" button for comments on post people reply to?

i recently discovered that if you choose constrained L2 on two plane datums and callout parrellism in legacy they return absolute 0. why is that?

I assume they are constructed primary datum planes? The constructed primary datum plane, secondary datum line and tertiary datum point were added purely to provide a way for legacy users to construct alignments which satisfied the new datum math rules. They are not supposed to be dimensioned themselves since they contain no hits (the help file does state this). Those constructions are not necessary when working with the geometric tolerance command because it performs the constrained L2 calculation automatically in the background when you have DEFAULT datum math and DEFAULT feature math selected. As you are seeing, when working with the geometric tolerance command, most constructions are unnecessary and can actually get in the way. It's sort of the opposite concept to "traditional" CMM programming where users previously had to get creative and employ constructed features because of the limited dimensional capabilities of older software packages.