Pc Dmis Training

Level 1 Training

Welcome to Brown & Sharpe’s

Telford Technical Centre

Developed By:

Ryan Stauffer

Application Engineer

Commercial Operations

Measuring Systems Group

Metrology HouseHalesfield 13, TelfordShrops. TF7 4PL.

e

Additional Information

Peter Hughes

Training Officer

Measuring Systems Group

Course Objectives

Course Objectives

• Understand why and how a Probe Qualification is performed

• Get a thorough understanding of how we create Part Alignments

• Understand how PC-DMIS handles Solid Geometry

• Learn how to Edit your part programs

• Write a logical, organized part program from beginning to end

The Cartesian Coordinate System

X

Z

Y

Z

X

Y

X

Z

Y


ORIGIN

The measurement VOLUME of a CMM can be represented by a cube. Each direction within the cube is an AXIS. The ORIGIN is the location where all three axes intersect.

X

Z


Y

| | | | | | | |

10

0

10

5

5 10

5

Each axis is divided into equal divisions, representing the units of measurement. Any point in the measurement cube can be defined in terms of a unique X, Y, and Z value.

X

Z


0

Y

| | | | | | | |

10

5

0

10

5

0 5 10

What are the

coordinates of:

X = 10

Y = 5

Z = 5

Y

| | | | | | | |

10

5

0

10

5

0 5 10

X = 0

Y = 0

Z = 5

Y

| | | | | | | |

10

5

0

10

5

0 5 10

X = 10

Y = 10

Z = 0

Probe Head (Wrist) & Touch Trigger Probe (Ttp)

Articulating Probe Head

The A axis rotates from 0° to +105° in 7.5° increments

Articulating Probe Head

B axis rotates from -180° to +180° in 7.5° increments

Touch Trigger Probes

Mechanical Probes such as the TP2 contain 3 electrical contacts. When the stylus is deflected, at least one of the contacts is broken. At this instant, the machine’s X, Y, and Z scales are read. These values represent the ball center position of the stylus at the time of contact.Contact

Broken


Touch Probe Example #1 :

Measuring point on side of part

Recorded point


Touch Probe Example #2 :

Crashing into part with high velocity

Bent probe tip

OUCH !!!

Probe Qualifications

Probe Qualification

Artifact with Known Diameter, Traceable to National Standards

PROBE QUALIFICATION is the process of defining effective probe diameter and position of the probe tip for measurement. To accomplish this, a qualification artifact with a known diameter is measured with the probe tip to be qualified.

Probe with Unknown Position and Diameter to be Qualified

Probe Qualification

Ball Centre coordinates at each measurement point around the artifact are compared to the known artifact diameter. The effective probe diameter is calculated from the difference between this diameter and the diameter of the spherical pattern of the measured points.

Effective Probe Radius

Building The Probe

Probe Qualification

Working Planes Of PcDmis

PC-DMIS Working Planes

X

Z

Y

ORIGIN

In PC-DMIS, it is important that the correct WORKING PLANE is specified for measuring circles, calculating 2D distances, etc. The available working planes are: Y MINUS

Z PLUS

Y PLUS

X

MINUS

X

PLUS

Z MINUS


What Is A Working Plane

The working plane is the view that you are currently looking from, for instance if you wish to measure the top surface of a part, then you are working in the ZPLUS working plane. If you are measuring features in the front face you are in the YMINUS working plane. This selection is important when you are working in polar co-ordinates, because PcDmis uses the working plane to decide where Zero Degrees (start point) is for that work plane.


* In the Zplus plane, zero deg is in the +X direction

and 90 deg is in the +Y direction.

* In the Xplus plane, zero deg is in the +Y direction and 90 deg is in the +Z direction. * In the Yplus plane, zero deg is in the -X direction and 90 deg is in the +Z direction.

+ X

+Y

0 deg

45 deg

90 deg

135 deg

180 deg

225 deg

270 deg

315 deg

Circle Measurement Direction

Vectors

Directional Cosines

I

K

J

Vectors

X

Z

Y

Directions of features and directions for probe approach to a point are represented by VECTORS. A vector can be thought of as a line 1 unit long, pointing in the direction of the vector.

(+I direction)

(+J direction)

(+K direction)The directions of a vector relate to the three axes of the coordinate system. The I direction is the direction of the X axis, J direction is the direction of Y, and K is the direction of the Z axis.

Vectors

X

Z

Y

(+I direction)

(+J direction)

(+K direction)What is the vector direction of :

I = 1.0

J = 0.0

K = 0.0X

Z

Y

(+I direction)

(+J direction)

(+K direction)

I = 0.0

J = 0.0

K = -1.0

I = 0.7071

J = 0.7071

K = 0.0

Cosine of 45o 45°

Incorrect Vector = cosine error

Introduced Error

Normal Vector

Expected Contact Point

Nominal Contact Point

Approach Direction

Angle

Probe Dia 0.5 1.00 2.00 3.00 4.00 6.00Angle Error Magnitude of error introduced by not probing normal to surface

1.0° 0.0000 0.0001 0.0002 0.0002 0.0003 0.00055.0° 0.0010 0.0019 0.0038 0.0057 0.0076 0.011510.0° 0.0039 0.0077 0.0154 0.0231 0.0309 0.046315.0° 0.0088 0.0176 0.0353 0.0529 0.0709 0.105820.0° 0.0160 0.0321 0.0642 0.0963 0.1284 0.1925

Ali

gnm

ent

Alignment

Alignment

Alignment

Alignment is the process of establishing a part coordinate system, where the Axes of the part and CMM are the same.

Three things are needed to complete a part alignment:

• A LEVEL (Any measured feature with a vector direction). The level feature controls the orientation of the working plane.

• A ROTATE AXIS (Any measured feature with a vector direction). The rotate feature needs to be perpendicular to the level feature. This controls the “timing” or rotational position of the axes relative to the working plane.

• An ORIGIN (Any measured feature or features which define the X, Y, and Z zero point of the part).

X

Z

Y

Machine Home Position

Desired Part Coordinate System

Alignment

Level Feature = Plane

Rotate Axis Feature = Line

Origin Feature = Circle

X

Z

Y

X

ZY

X

ZY

STEP 1 : Level Z Axis to Plane

X

ZY

STEP 2 : Rotate X Axis to Line

X

ZY

STEP 5 : Translate Z Origin to Plane

ALIGNMENT ALIGNMENT

COMPLETED!!!!COMPLETED!!!!

ALIGNMENT ALIGNMENT


X

ZY

STEP 3 : Translate X Origin to CircleSTEP 4 : Translate Y Origin to Circle

X

Z

Y

Machine Home Position

Required Part

Origin Position

Alignment

Level Feature = Plane

Rotate Axis Feature = Line

Origin Feature = CornerX

Z

Y

X

ZY

STEP 1 : Level Z Axis to PlaneSTEP 2 : Rotate X Axis to Line

STEP 5 : Translate Z Origin to Plane

ALIGNMENT ALIGNMENT


ALIGNMENT ALIGNMENT

COMPLETED!!!!COMPLETED!!!!STEP 3 : Translate X Origin to PointSTEP 4 : Translate Y Origin to Line

How To Align a Part

Measure 3 Points To Create Plane

Measure 2 Points To Create Line

Measure 1 Point On Side Face

Building The Alignment

Alignment How To Do It

Click The Utilities Option And Then Select

Alignment

Alignment How To Do It

From The Features List Select

PLN1

LINE1

PNT1

Click On Auto Align

PcDmis will automatically align the part by Levelling and setting Z zero to PLN1

Rotate and set Y zero to LINE1, and then set X zero to PNT1.

Measured Features

Geometric Elements

Basic Geometric Elements

Element: POINT

Min Points: 1

Position: XYZ location

Vector: None

Form: None

2D/3D: 3D

EXAMPLE

Y

5

5

5

Z

X

Output X = 5

Y = 5

Z = 5


Element: LINE

Min Points: 2

Position: Centroid

Vector: From 1st to last point

Form: Straightness

2D/3D: 2D/3D

EXAMPLE

Y

5

5

5

Z

X

Output X = 2.5 I = -1

Y = 0 J = 0

Z = 5 K = 0

12


Element: CIRCLE

Min Points: 3

Position: Centre

Vector*: Matches reference plane

Form: Roundness

2D/3D: 2D

EXAMPLE

Y

5

5

5

Z

X

Output X = 2 I = 0 D = 4

Y = 2 J = 0 R = 2

Z = 0 K = 1

1

2

3

* The vector of a circle is only for measurement purposes, and does not uniquely describe the feature’s geometry.


Element: PLANE

Min Points: 3

Position: Centroid

Vector: Perpendicular

Form: Flatness

2D/3D: 3D

EXAMPLE

Y

5

5

5

Z

X

Output X = 1.67 I = 0.707

Y = 2.50 J = 0.000

Z = 3.33 K = 0.707

1

3

2


Element: CYLINDER

Min Points: 5

Position: Centroid

Vector: From 1st level of hits to last level

Form: Cylindricity

2D/3D: 3D

EXAMPLE

Y

5

5

5

Z

X

X = 2.0 I = 0 D = 4

Y = 2.0 J = 0 R = 2

Z = 2.5 K = 1

2

3

54

1


Element: CONE

Min Points: 6

Position: Apex

Vector: From 1st level of hits to last level

Form: Conicity

2D/3D: 3D

EXAMPLE

Y

5

5

5

Z

X

X = 2.0 I = 0 A = 43deg

Y = 2.0 J = 0

Z = 5.0 K = 1

2

3

564

1


Element: SPHERE

Min Points: 4

Position: Centre

Vector*: Toward North Pole of Hits

Form: Sphericity

2D/3D: 3D

EXAMPLE

Y

5

5

5

Z

X

X = 2.5 I = 0 D = 5.0

Y = 2.5 J = 0 R = 2.5

Z = 2.5 K = 1

1

24

3

* The vector of a sphere is only for measurement purposes, and does not describe the feature’s geometry.

Constructed Features

Points


POINT : AT ORIGIN

X

Z

Y

POINT

A point is constructed at the origin of the current alignment system. Coordinates of the point will be 0, 0, 0.


POINT : CAST

A point is created at the centroid of the selected feature. Its coordinates (x y z) are equal to that of the Circle

POINT

INPUT : CIRCLE1

CIRCLE1


POINT : CORNER

A point is created at the intersection of three planes.

INPUT : PLN1

PLN2

PLN3

PLN1

PLN2

PLN3

POINT


POINT : PIERCE

A point is created where feature 1 pierces the surface of feature 2. The order of selection is Important

INPUT : CYL1

PLN1

Y

5

POINT

PLN1

CYL1


POINT : OFFSET

X

Z

Y

POINTA point is created at the specified offsets from the selected feature.

INPUT : PNT1

X Offset = 0

Y Offset = 4

Z Offset = 1

PNT15

5

5


POINT : INTERSECT

A point is created at the location where the two selected features cross.

POINT

INPUT : LINE1

LINE2

LINE1

LINE2


POINT : DROP

A point is created by projecting the first feature’s centroid onto the second feature (line, cone, cylinder, or slot).

POINT

INPUT : CIRCLE1

LINE1 LINE1

CIRCLE1


POINT : MID

A point is created at the midpoint of the two selected features.

POINT

INPUT : CIRCLE1

CIRCLE2

CIRCLE1 CIRCLE2


POINT : PROJECT

INPUT : PNT1

PLN1

A point is created by projecting the feature onto the selected plane.

PNT1

PLN1

POINT


Circles


CIRCLE : BF

INPUT : CIR1

CIR2

CIR3

CIR4

A best-fit circle is created through the selected features.

CIR1

CIR4

CIR3

CIR2

CIRCLE


CIRCLE : CONE

INPUT : CONE1

DIAMETER = 2”

A circle is created inside a cone at the specified diameter.

4”

CONE1

2”

CIRCLE


CIRCLE : INTERSECT

INPUT : CONE1

PLN1

A circle is created at the intersection of a plane and a cone, cylinder, or sphere.

CONE1

CIRCLE

PLN1


Lines


LINE : ALIGNMENT

X

Z

Y

LINE

A line is created along an axis of the current coordinate system, perpendicular to the current working plane.

CURRENT WORKPLANE = Z+

Z+ PLANE


LINE : BF

A best-fit line is created through the selected features.

INPUT : CIR1

CIR2CIR2

CIR1

LINE


LINE : INTERSECT

INPUT : PLN1

PLN2

A line is created at the intersection of two planes.

PLN2

PLN1

LINE


LINE : PERP

A line is created perpendicular to the first selected feature, passing through the second feature

INPUT : LINE1

CIRC1 LINE1

CIRC1

LINE


LINE : PARALLEL

A line is created parallel to the first selected feature, passing through the second feature.

INPUT : LINE1

CIRC1 LINE1

CIRC1

LINE


LINE : REVERSE

INPUT : LINE1

A new line is created in the opposite direction of the selected line.

LINE

LINE1


LINE : OFFSET

A line is created through the centre of the first feature, passing by the second feature at the specified offset.

INPUT : CIR1

CIR2

OFFSET = 1”

CIR2

CIR1

1”

LINE

Dimensioning Features

Location


LOCATION

The dimension LOCATION option reports the specified characteristic of the selected feature. Characteristics that can be reported are:

angrad


LOCATION

X

ZY

CIR1

1 2 3

2

3

1

EXAMPLE:

Reporting CIR1

X = 2Y = 2Z = 0D = 2R = 1

2

1

2

1

0


LOCATION

X

ZY

CONE1

1 2 3

3

1

EXAMPLE:

Reporting CONE1

A = 60°

V = 0, 0, 1

(I, J, K)

2

1

0

2 60°


LOCATION

X

ZY

POINT1

1 2 3

23

1

EXAMPLE:

Reporting POINT1

Prad = 2.828

Pang = 45°

2

1

0

2.828

45°


True Position


TRUE POSITION

The following is an example of “normal” tolerancing of a Circle:

2.00 ± .05

1.00 ± .05

1.00 ± .05 0.1

0.1


TRUE POSITION

Zooming in on the theoretical circle centre...

GOOD

OUT OF TOLERANCE

Location of measured circle centre:

2.05.95

1.95

1.05


TRUE POSITIONWhy are two points the same distance from nominal not both in tolerance?

GOOD

OUT OF TOLERANCE

True Position tolerance zone

True Position tolerancing creates a circular tolerance zone, which better judges parts based on the fit and function of mating parts

MMC

Maximum Material Condition

True Position

40

30

Ø0.15 A

Ø20+/- 0.2

Dia Bonus MMC

19.80 0 0.1519.90 0.10 0.25

20.00 0.20 0.3520.10 0.30 0.45

20.20 0.40 0.55

NB: The bonus will not be applied if the Dia of the hole is out of toleranceSizes in MM

MMC -MMC

Maximum Material Condition - Maximum Material Condition

True Position

Dia A Dia 2MMC - MMC

19.80 19.80 0.1519.90 19.90 0.35

20.00 20.00 0.5520.10 20.10 0.75

20.20 20.20 0.95

40

30

Ø0.15 A

Ø20+/- 0.2

Ø20+/- 0.2

A

NB: The bonus will not be applied if the Dia of the hole is out of tolerance

LMC

Least Material Condition

True Position

Dia Bonus LMC

19.80 0.40 0.5519.90 0.30 0.45

20.00 0.20 0.3520.10 0.10 0.25

20.20 0. 0.15

40

30

Ø0.15 A

Ø20+/- 0.2

NB: The bonus will not be applied if the Dia of the stud is out of tolerance

LMC - LMC

Least Material Condition - Least Material Condition

True Position

Dia A Dia 2LMC-LMC

19.80 19.80 0.9519.90 19.90 0.75

20.00 20.00 0.5520.10 20.10 0.35

20.20 20.20 0.15

Ø20+/- 0.240

30

Ø0.15 A

A

NB: The bonus will not be applied if the Dia of the stud is out of tolerance


2D Distances


DISTANCE 2D

The 2-dimensional distance option calculates distances between features within the current working plane.

TYPICAL 2D DISTANCE USAGE : Point to Line or Circle to Circle or Circle to Line


DISTANCE 2D

When calculating a 2-Dimensional distance, you have many options to determine which distance to report. For Example, you could report these distances from CIR1 to CIR2 :

DIST1

DIS

T2

DIST3

X

Y

CIR2

CIR1


DISTANCE 2D

DIST1

DIS

T2

DIST3

X

Y

The options available are:

• Centre to Centre• To Feature• To X Axis• To Y Axis• To Z Axis

• Parallel to

• Perpendicular to

DIST1 can be created using:

• To X Axis, Parallel to

• To Y Axis, Perpendicular


• To Y Axis, Parallel to

• To X Axis, Perpendicular


• Centre to Centre (no “To” axis selected)

&


DISTANCE 2D

The “To Feature” option can be used when a distance to be calculated is not parallel or perpendicular to an axis of the current coordinate system.

The order of feature selection is important for this option. The distances are calculated to either Perpendicular or Parallel to the SECOND feature, based on your selection.


DISTANCE 2D

How can you report the overall length of this part?

Measure a line on one side, a point on the other.

LINE1

PNT1DISTANCE

Report the 2D Distance from PNT1 to LINE1, using the “To Feature” option, Perpendicular to LINE1.


DISTANCE 2D

If you just click on PNT1 and LINE1, and choose no “To” option, the distance will be straight from the line’s centroid to PNT1. THIS IS NOT WHAT YOU WANT!!!!!!!!!!!!!!

LINE1

PNT1DISTANCE


DISTANCE 2D

When calculating 2-Dimensional distances, it is very important that the correct WORKING PLANE is selected.In the last example, the working plane was set to Z PLUS.

X

Y

Z PLUS Working Plane


DISTANCE 2D

The ADD RADIUS and SUB RADIUS option modifies the calculated distance to include or subtract the radii of dimensioned circles.

X

Y

Normal Distance

ADD RADIUS DistanceSUB RADIUS Distance


3D Distances


DISTANCE 3D

3-dimensional distances calculate the shortest distance between two features, regardless of the working plane.

TYPICAL 3D DISTANCE USAGE: Point to Plane


DISTANCE 3D

3D Distance from PNT1 to PLN1

PLN1

PNT1

DISTANCE

EXAMPLE:


ANGLES

An angle is created at the intersection of two lines

LINE 1

LINE 2

ANGLE

60°

Perpendicularity

0.15 A

A

0.15 Wide Tolerance Zone

Possible orientation of the actual surface

A

Parallelism



A

0.15 A

A

Angularity

35°

0.5 A

A

35°

A



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