Calypso Curve Instructors Guide

Calypso 3.6 Curve class instructors guide

Day 1 1. Introduction and course structure









Have the students sign the class attendance sheet. Introduce yourself and describe the facilities, location of rest rooms etc. Class hours, breakdown of the day, lunch arrangements. The course participants introduce themselves – obviously this is optional as some people do not like to be put on the spot. The coordinate measuring machines (CMM) in the course – describe the machines to be used in the class and ask the students what type of machines they have. There is no point concentrating on scanning strategies if the student has a touch trigger machine. Also it may be a good time to group the students according to their probe types. Note: This class uses the “KUM” block extensively for the lab exercises, therefore make sure that these blocks are available.

2. Structure of the manual


The first 20 pages of the manual contain the theory of curve, the remainder of the manual consists of lab exercises. The intent is that a segment of theory is discussed and then a practical lab exercise is undertaken by the students to reinforce it. As is normal, if there are two students on a machine then both students should do the exercise. In previous classes, approximately 4 hours was made available to cover the Curve option, this class has 3 days and so there is plenty of time for the student to get into curve.

3. Theoretical foundations of curve measurement


This first section is the basic explanation of what Curve is and how it can be created. This is covered in the manual in sections 1 through 3: This really serves as an overview of curve, the students will be doing practical exercises to reinforce these concepts. o o o o o




Introduction Normal direction and directional cosine Definition and presentation of curves 2D-, 3D curves Importing nominal values

Worksheet 1 – Importing nominal values. o

Point generator Mention the ability to create data via formula, but this is not actually covered until Worksheet 16




Worksheet 2 – Entering points from the keyboard




Worksheet 3 – Digitizing an unknown curve – section 4.3 covers this.




Worksheet 4 – Extracting curve data from a CAD model – section 4.4 covers this topic.

4. Manipulating nominal points and vectors.


Section 5 covers the theory behind manipulating nominal points and vectors.




Worksheet 5 – transforming nominal data. This exercise uses the airfoil on the front of the block. The nominal data is read in from a file and is then rotated and translated to allow the same airfoil shape on the right side of the part to be measured.




Worksheet 6 – changing nominal vectors This exercise uses the curve around the top of the part. Once this curve has been created, it is copied to create a second curve. The second curve is modified to allow a scan on the top surface at a distance in from the original curve. The second curve is linked to the first curve by means of the “Parallel Curve” option. This ensures that any change in the shape of the first curve will update the second curve.




Worksheet 7 – Approximation In this exercise the student is asked to digitize around the trailing edge of the airfoil on the front of the block. Approximation is introduced as a means of controlling the shape of the curve. A spline is fit through the points which has a variable smoothing factor. Simulation can be selected as a way of experimenting with the value before committing to a setting. The smoothing factor is a value between 0 and 1, when set to 0 no smoothing takes place. When set to “1” the optimal smoothing is carried out. Sorting the actual data points is also introduced as a means of controlling the order of points sent to the curve when scanning around a very small radius.

Day 2 5. Segments and applying tolerances to segments


Worksheet 8 – segmenting a curve




Worksheet 9 – curve jump tolerance. The jump tolerance relates to the difference between the adjacent actual and nominal points. If this value is exceeded the curve will be reported as being out of tolerance.

6. Evaluation


The theory on the evaluation settings for a curve are covered in section 7 through 7.4.




There is no separate lab to cover the evaluation settings and so use a previous lab and experiment.

7. End recognition


The theory of “End Recognition” is covered in section 7.6. You now have a choice of methods in determining the end position of a scan. If sphere is selected, then when the probe passes the centerline of the defined diameter the scan will stop. If

plane is selected, then a line is drawn from the start to the end point and a plane is calculated perpendicular to this line. When the probe passes this plane the scan stops. This can however give rise to two possible stop points and so should be used with caution.


No special lab has been created for this setting.

8. Scanning techniques


Section 7.7 covers the theory. There is now a check box in the strategy of a known curve that allows you to access the options available for an “unknown curve”. This includes the selection of end conditions and the reduction of data at the beginning and end of the scan.

9. Digitizing a 3D Curve


Worksheet 10 – Digitizing a 3D curve. In this lab a 3D curve is digitized on the spherical section of the test piece. The important thing to remember when digitizing a 3D curve is the order of the points used to define the start end points of the scan. Make sure that the first three points define the start position for the three lines and the next three should define the end points.

10. Generating a lift curve


Worksheet 11_1 Generating a Lift curve. This lab is in two parts, the first reads in the nominal data from a VDA file (liftcurve.vda) and the second digitizes the same curve. The list curve is in the top center of the test part. When digitizing the lift curve remember that Calypso needs to be told that it is dealing with a lift curve. Also the same rule applies to the order of the first three points i.e they define the start position of the three lines.

11. Generating a co-ordinate system from a curve.


Worksheet 12 – Generating a co-ordinate system Calypso now allows you to create a secondary alignment from a best fir curve.

12. Reading in ASCII data


Worksheet 13 - Reading in ASCII data On the CD is a file called curve.txt which is the nominal data for the large bore in the front face of the cad cube part. This can be used as an example to read in or create your own prior to the class.

13. Exporting Data


Worksheet 14 – Exporting as a VDA file

This example uses the cad cube part. The wires of the banana slot are used to create a curve with 200 points. The nominal data is then saved as a VDA file.


Worksheet 15 – Exporting as ASCII data This lab exports the actual data created from the previous lab. This data is exported using the “Results to File” option.

Day 3 14. The point generator.


Worksheet 16 – Producing nominal values using the point generator. This lab uses the cad cube part. The nominal data for the banana curve is created using the point generator within the curve feature. There are four separate curve features, one for each arc. Using formula the individual points are calculated for each arc segment. Be prepared to explain the function of the “point” variable and the loop counter “index”.




Worksheet 17 – Producing nominal data for a spiral using the point generator. This is a theoretical exercise whereby a 3-turn spiral is created using formula and the point generator. Be prepared to explain the formula and pay special attention to the parentheses.

15. Scanning techniques.


Worksheet 18 – Scanning techniques. This lab looks at the use of the use of the start and end conditions mentioned in section 7.6 and 7.7. The student is also asked to digitize the curve on the top and enter various evaluation settings. This lab allows the student to experiment a little with the various options.

16. Arbitrary curve sections from the CAD model


Worksheet 19 – Sections through a CAD model This lab uses the cad cube test part. A section is to be taken through the part at a specified height and a curve created at the intersection of the plane and the model. Don’t miss the “Combine CAD entities” step this acts like a mode switch, without this step the procedure does not work.

Worksheets: 1. 2. 3. 4. 5. 6. 7. 8. 9.

Producing nominal values: importing nominal values Curve measurement on a slot Producing nominal values: Enter nominal values Some additional points are entered to an existing curve Producing nominal values: digitizing Digitizing a 2D curve Producing nominal values: extracting from the CAD model Changing nominal points Transforming Changing nominal vectors Rotation around tangents, shifting parallel curves Evaluation methods Approximation Tolerances Segmenting Curve step tolerance An example

Further exercises: 10. Digitizing a 3D curve An example 11. Lift curve 1. Measuring a lift curve against imported data 2. Digitizing a curve An example 12: Creating a coordinate system An example 13. Importing an ASCII-File An example 14. Exporting data – VDA file from nominal values An example 15. Exporting data - ASCII-File from actual values An example 16. Producing nominal values: point generator Mathematically generate a curve on the work piece 17. Measuring spirals Spiral data is generated with the point generator 18. Digitizing and measuring – end recognition Options for 2D curves and 3D curves with end recognition 19. Arbitrary curve sections from the CAD model Extracting 2D curves and 3D curves from the CAD model.