Gd&t & Pcdmis

[RClone]

Can anyone school me on what PCDMIS does behind the scenes?
Our engineer wants to know how the machine measures.
When you construct a plane from other planes, does it use all the points,or just the centroid? What does it use the sample hits on auto features for?
Just to level the measurment or part of the measurement calculation?
What is "least squares"?
Finally what is "datum shift" and how would you use it like bonus tolerence?
last question:
Is it too early for beer?

Lost without you guys ...RFC

[Matthew D. Hoedeman]

Can anyone school me on what PCDMIS does behind the scenes?
Our engineer wants to know how the machine measures.
When you construct a plane from other planes, does it use all the points,or just the centroid? What does it use the sample hits on auto features for?
Just to level the measurment or part of the measurement calculation?
What is "least squares"?
Finally what is "datum shift" and how would you use it like bonus tolerence?
last question:
Is it too early for beer?

Lost without you guys ...RFC

When using a pre-measured (or pre-=existin) feature, Pcdmis always used the constructed centroid of that feature.

Surface sample hits allow YOU to tell Pcdmis to sameple the surface so that the DEPTH of measurement can be set to an exact value BELOW the REAL surface, not the design (cad) surface.

Never too early for beer.

[Wes Cisco]

Ah, the infamous datum shift. The idea is that if you have a modifier on a datum (MMC or LMC) and you have measured and select that datum and assign the modifier to it in the Trueposition window, pc-dmis will allow the location of that datum to shift around within it's tolerances to achieve a sort of best fit with regards to the feature in question. This really gives you more of go/no go answer than a typical straight forward Trueposition answer. The intent is to mimic a hard gage and prove or disprove functionality based on the FCF, (Feature Control Frame - that is the GD&T box). If you do a search for Trueposition you will find many threads and some posted documents that may help. HTH (Hope This Helps.)

P.S. Whiskey is better than most things, and Whiskey before breakfast better than most songs!