distance measurement

[[Jo...]]

I am measuring a part. the print calls out a distance of 7.00" +/- .050. I am scanning both planes and doing a Cartesian distance between the two. Customer is complaining that how do I know that the min and max don't fall out of print. he wants it measured at several different points and report distance on each of them. Is there a way to simply give max and min of the distance between the 2 planes I am scanning? This guy is being an ass and wants it on all distances that are planes.

[[Da...]]

The quick answer would be to ask for parallelism.
(+/- .050, and you're checking it on the CMM ??)

[[Jo...]]

yes +/- .05" and .03" on a machined part and the customer is being an ass about the distance dimensions. Im scanning planes and they wont change their print and don't call out parallelism.

[[Ca...]]

You could create two distance characteristics, the first reporting the distance with both planes evaluated with Inner Tangential Element, and the second evaluates the planes with Outer Tangential.

Wouldn't that work?

[[To...]]

Here's a presentation converted to pdf by Ryan Stauffer, a Calypso Yoda.

LNL Distance.pdf

[[Jo...]]

I will try that and see if it makes this guy happy. His exact words "Since Calypso does not display the min/max variations of the points measured, there's no way to tell if the dimensions are correct over their entire length.". I mean really +/- .050" and .030" with no parallelism callout and he's worried about that. its called out as just a distance.

[[De...]]

Well based on the spec hes not wrong, he might be being a stickler, but he is correct that all opposing points should be within the limits of size.

That lunch and learn powerpoint that was posted is very good for explaining the difficulties of checking a distance 'correctly' versus efficiently.

[[Za...]]

According ISO 14405-1:2010 (i don`t have actual version 2013) distant must be checked as to point distance, so part at a picture is good. I understand that it was bad idea for assembly, but it was a standard. For diametrical dimension Calypso have correct characteristic, but for distance haven't.

Снимок.PNG

[[An...]]

You have to check also the envelope. (size 12)
Part is not within spec.

[[Aa...]]

A true "distance" (not the size of a feature of size), is subject to a lot of interpretation, as described in ISO 14405-2. That said, you're talking about two opposing planes, ISO and ASME both treat that as a feature of size (in ISO, it's in stated in 15530-3). Calypso has a lesser-known feature type Symmetry Plane (not to be confused with the symmetry on the construction menu). I would recommend using that, and evaluating both outer tangential and inner tangential (to build on what Casey said).

[[Da...]]

hello i have to measure this drowing of go /nogo fixture
inside distances are 12.7 ; 13.7 +/- 0.01 mm


i'm wondering how to measure this distances inside of this small and curved feature, - its machined very ugly , i have short lines scanned without CAD
i tryed outer tangential as evaluation on lines but it gived me i think wrong result because outer tangential lines in this example may look like my purple line here :
so i should use outer tangential with constraint to normal - so it will give me witch should look like brown line on my screeanshot, do i think corectly ?

axis here i decided to make of symety of the outer dimmension



if someone can also explain they created this points ?
or meybe its best to do it on cuvers? (i do not have CAD) i will search for it..

[[Ma...]]

If you don't have a model and want to use curves, then prepare features for it. Make some lines, planes and points to make base alignment. Then you can use unknown contour for curve. When you are recalling measured points don't forget to uncheck "recalculate nominals" before selecting feature.

Use outer tangential on lines and you can use caliper distance to use max/min - but not from measured points, just from geometry.
You can even correct nominal length of lines to match "caliper" size.