Understanding
Flatness, Parallelism, & Profile
in Calypso
Flatness
When you report form characteristics, like Flatness, in
Calypso, the result is determined by the distance between
two perfect pieces of geometry, “squeezed” as close together
as possible containing the actual measured points of the
feature.
This is calculated by default using a special Evaluation
Method, called “Minimum Element”.
Note that this result for Flatness (form) is different than the
FORM listed in the feature’s window of Calypso, as that is
typically calculated using the LSQ Evaluation Method.
Parallelism
When reporting Parallelism of one plane to another in
Calypso, the result can be thought of as the distance between
two planes, parallel to the datum, that contains all of the
actual measured points of the feature being evaluated.
By default, the LSQ evaluation method is used to determine
the orientation of the Datum.
Note that in the Parallelism Characteristic, secondary
datums are not necessary if you are evaluating two 3dimensional features, like planes.
Profile
When you report “Profile” of a 3-D geometric feature in
Calypso, the default result can be though of as the thickness
of a zone, centered on the nominal geometry of the feature
being reported, that contains all of the measuring points of
the feature.
By its nature, “Profile” is a combination of size, form,
orientation, and position errors.
Calypso uses your Feature Nominals to determine the
“target” shape and location of the feature.
*When reporting Profile, MAKE SURE ALL YOUR
FEATURE NOMINALS ARE CORRECT, including A1 and
A2 projection angles.
Example Print:
3.0 A
2.0 B
1.0
B
10.00
A
Assume Datum
B is perfectly
Flat, located
exactly at 10.00
3.0 A
Surface to
Evaluate
2.0 B
1.0
B
10.00
A
The next several slides show the results for Flatness,
Parallelism, and Profile for five different point patterns on
the surface to be evaluated.
Notice how position, orientation, and form errors in the
points that make up the evaluated surface affect the results
of Flatness, Parallelism, and Profile.
Actual characteristic windows from Calypso are shown,
along with explanations of why each result is calculated the
way it is.
Flatness
Actual
Probing Points
11.0
10.0
9.0
Flatness = 0
Flatness
Actual
Probing Points
11.0
10.0
Why The Answer?
Distance of
Flatness Result For a plane, if all points lay on a
perfectly flat plane, regardless
of orientation or position, the
result will be zero.
A perfect form result is zero.
9.0
Flatness = 0
Parallelism
Actual
Probing Points
11.0
10.0
9.0
Parallelism = 0
Parallelism
Actual
Probing Points
11.0
10.0
Why The Answer?
Distance of
Parallelism
If all the points lay in a perfectly
flat plane, perfectly oriented to
match the datum, the result will
be zero.
9.0
Parallelism = 0
Profile
Actual
Probing Points
11.0
10.0
9.0
10.00
Profile = 0
Profile
Actual
Probing Points
11.0
Why The Answer?
Thickness of
Profile Zone
10.0
Since Profile is the the thickness
of a zone centered on the
nominal geometry, if all
measured points are exactly on
the nominal, the thickness of the
zone would be zero.
9.0
A perfect Profile result is zero.
10.00
Profile = 0
Flatness
Actual
Probing Points
11.0
10.0
9.0
Flatness = 0
Flatness
Why The Answer?
11.0
10.0
Distance of
Flatness Result For a plane, if all points lay on a
perfectly flat plane, regardless
of orientation or position, the
result will be zero.
A perfect form result is zero.
9.0
Flatness = 0
Parallelism
Actual
Probing Points
11.0
10.0
9.0
Parallelism = 1
Parallelism
Distance of
Parallelism
11.0
10.0
9.0
Why The Answer?
In this case, a perfectly flat
plane shows Parallelism
deviation due to the angle of the
plane relative to the Datum.
The result is the distance
between two planes, parallel to
the datum, that contains all the
measured points.
Parallelism = 1
Profile
Actual
Probing Points
11.0
10.0
9.0
10.00
Profile = 2
Profile
Thickness of
Profile Zone
11.0
Why The Answer?
Since Profile is the the thickness
of a zone centered on the
nominal geometry, the result
will be two times the distance of
the most distant point from the
nominal geometry.
10.0
9.0
10.00
Profile = 2
Flatness
Actual
Probing Points
11.0
10.0
9.0
Flatness = 2
Flatness
Distance of
Flatness Result
11.0
10.0
Why The Answer?
In this case, the distance
between two perfect planes
parallel to each other that
contain the measured points is
2.0.
9.0
Flatness = 2
Parallelism
Actual
Probing Points
11.0
10.0
9.0
Parallelism = 2
Parallelism
Distance of
Parallelism
11.0
10.0
9.0
Why The Answer?
In this case, a plane which is
perfectly parallel to the datum
(using LSQ fitting) shows a
high amount of parallelism
deviation. This is because of
the form error of the feature.
The result is the distance
between two planes, parallel to
the datum, that contains all the
measured points.
Parallelism = 2
Profile
Actual
Probing Points
11.0
10.0
9.0
10.00
Profile = 2
Profile
Thickness of
Profile Zone
11.0
Why The Answer?
Since Profile is the the thickness
of a zone centered on the
nominal geometry, the result
will be two times the distance of
the most distant point from the
nominal geometry.
10.0
9.0
10.00
Profile = 2
Flatness
Actual
Probing Points
11.0
10.0
9.0
Flatness = 0
Flatness
Why The Answer?
11.0
For a plane, if all points lay on a
perfectly flat plane, regardless
of orientation or position, the
result will be zero.
10.0
A perfect form result is zero.
9.0
Distance of
Flatness Result
Flatness = 0
Parallelism
Actual
Probing Points
11.0
10.0
9.0
Parallelism = 0
Parallelism
Why The Answer?
11.0
If all the points lay in a perfectly
flat plane, perfectly oriented to
match the datum, the result will
be zero.
10.0
Note that position error does not
effect the Parallelism result.
9.0
Distance of
Parallelism
Parallelism = 0
Profile
Actual
Probing Points
11.0
10.0
9.0
10.00
Profile = 2
Profile
Thickness of
Profile Zone
11.0
Why The Answer?
Since Profile is the the thickness
of a zone centered on the
nominal geometry, the result
will be two times the distance of
the most distant point from the
nominal geometry.
10.0
9.0
10.00
Profile = 2
Flatness
Actual
Probing Points
11.0
10.0
9.0
Flatness = 0
Flatness
Why The Answer?
11.0
10.0
Distance of
Flatness Result For a plane, if all points lay on a
perfectly flat plane, regardless
of orientation or position, the
result will be zero.
A perfect form result is zero.
9.0
Flatness = 0
Parallelism
Actual
Probing Points
11.0
10.0
9.0
Parallelism = 2
Parallelism
Distance of
Parallelism
11.0
10.0
9.0
Why The Answer?
In this case, a perfectly flat
plane shows Parallelism
deviation due to the angle of the
plane relative to the Datum.
The result is the distance
between two planes, parallel to
the datum, that contains all the
measured points.
Parallelism = 2
Profile
Actual
Probing Points
11.0
10.0
9.0
10.00
Profile = 2
Profile
Thickness of
Profile Zone
11.0
Why The Answer?
Since Profile is the the thickness
of a zone centered on the
nominal geometry, the result
will be two times the distance of
the most distant point from the
nominal geometry.
10.0
9.0
10.00
Profile = 2