Project Sheet  - CMM Measurements

 

Before we can begin using the Coordinate Measuring Machine to measure the Demo block, you must go through the preparation functions. Those function include:

 

1. Plan the measurement routine

2. Mount the part

3. Start up the machine

4. Find the machine home position

5. Locate the reference sphere position

6. Install the probe

7. Select the operating configuration

8. Qualify the probe tip

9. Align the part

 

Circle Feature

The first feature to be measured is the left rear circle on the top of the demo block. A circle is defined by an X, Y, Z cen­terpoint and a diameter.

Circles are measured with at least 3 hits on the surface of a cylinder. The cylinder's axis is assumed to be perpendicular to the working plane. To measure the circle:

 

1. Select "Measurements" on the Main Menu.

 

2. Select “Circle” on the Main Menu.

 

 

 

3. On the Circle Measurement screen, position the cursor so that the word "Message" is highlighted. Type in "MEASURE LEFT REAR 1" HOLE" and press "Enter".

 

 

4. Take at least 3 hits within the left rear hole on the demo part. Use the picture on the screen as a guide for the location of the hits. Select "Done".

 

 

5. On the Print Preview screen, make the following choices:

 

                                                Mode: Cartesian                       D Nom: 1

                                                Format: True Pos RFS D Upper Tol: .005

                                                Printer: Yes                              D Lower Tol: ‑.005

                                                Statistics: No                            True Pos Tol:.008

X Nom: 3.45

Y Nom: 1

 

 

Notice that the probe sense is "Inside". This means that Micromeasure III knows that we have just measured a hole and not an outside surface like a boss.

 

6. Select the "Label" field with the cursor and press "Enter". Type the following label: LEFT REAR 1" HOLE. This label will appear above the Print Preview information.
7. The results of the circle measurement will appear on the Print Preview screen and also print on the printer.
8. Select "Done". The results will be printed and the Main Menu will appear.

 

Roundness

After measuring a circle on the demo part, its roundness can be calculated with Micromeasure III. Roundness is the condition where all points are in a circle. To be considered round, the measured circle must fall within a specified toler­ance zone fromed by two concentric circles.

 

 

 

To measure a circle for roundness:

 

1. Select "Form Deviations" on the Main Menu.

 

 

2. Select "Roundness" on the Form Deviations Menu.

 

3. On the Roundness screen, position the cursor so that the word "Message" is highlighted. Type in "ROUNDNESS‑LEFT REAR 1" HOLE" and press "Enter".

 

4. Take at least 4 hits (8 recommended) on the left rear hole on the demo part. Use the picture on the screen as a guide for the location of the hits. For the correct probe compensation, move the probe to the center of the bore before removing it. Select "Done".
5. On the Print Preview screen, select the Label field with the cursor and press “Enter”. Type the follow­ing label: ROUNDNESS‑LEFT REAR 1" HOLE. This label will appear above the Print Preview infor­mation on the printout.

 

 

6. The results of the roundness measurement will appear on the Print Preview screen as well as the on the printer. In setting the tolerance for roundness deviation only an upper tolerance is selected, since a minus tolerance has no effect.
7. Select "Done". The results will be printed and the Main Menu will appear.

 

Concentricity

Next, determine the concentricity of the counterbore (larger circle) and the center bore (smaller circle). To measure for concentricity:

 

1. Select "Orientation" on the Main Menu.

 

2. Select "Concentricity" on the Orientation Menu by using the keys on the keyboard.

 

3. On the Concentricity screen, select the Message field. Type in "MEASURE LARGER HOLE FIRST THEN SMALLER HOLE" and press "Enter". This message will display on the screen when the measurement file is executed.

 

4. Take a minimum of 3 hits (6 recommended) on the counterbore hole (larger hole). Move the probe to the center of the bore before removing it. Select "Done".

 

 

5. Take a minimum of 3 hits (6 recommended) on the center bore (small hole). The probe must be long enough to reach the bore. Select "Done". Micro­measure will compute the concentricity of the counterbore to the center bore. The results will appear on the Print Preview screen.

 

 

6. On the Print Preview screen select the Label field with the cursor and press “Enter”. Type the follow­ing label: CONCENTRICITY‑COUNTER & CENTER BORE. This label will appear above the Print Pre­view information on the printout. Change the "D" upper tolerance to .004 and select "Done".

 

 

Center Bolt Hole

Measure the center bolt hole in the group of holes on the right side of the demo part.

 

 

 

1. Select “Measurements” on the Main Menu.
2. Select "Circle" on the Features Menu.

 

 

3. Position the cursor on the Message field and type "MEASURE CENTER.375 HOLE". Press "Enter".
4. Take a minimum of 3 hits within the hole. Press "Done". The results will appear on the Print Preview screen.
5. On the Print Preview screen select the Label field with the cursor and press “Enter”. Type "CENTER .375 BOLT HOLE". This label will appear above the Print Preview information on the printout. Set Format to “Full Display”.

 

 

6. Set the nominals and tolerances as follows:

 

            Nominal                 Upper Tol.                  Lower Tol.

X          2.55                             .005                            ‑.005

Y             0                               .005                            ‑.005

D          .375                             .004                            ‑.004

 

7. Select "Done".

 

Translate/Rotate

Next translate the point of origin to the center of the bolt hole that was just measured.

1. Select "Translate/Rotate" on the Alignments Menu.

 

2. Select "Translate To Last". This will translate the origin to the last feature measured, which was the center bolt hole.

 

 

 

3. Select "Done". The origin (0, 0, 0 point) is now at the center of the .375" hole just measured. To ver­ify this on the Main Menu screen, select "Display Axis". The CRT now displays the XYZ position of the probe. Move it to the center of the .375" hole.The display should read close to "0" which will con­firm the translation. Measure the small rear bolt hole.

 

Rear Bolt Hole

Measure the small rear bolt hole.

 

                                                                                                                                                           

1. Select "Micromeasure" on the "Display Axis" screen to return to the Main Menu.
2. Select “Measurements” on the Main Menu.
3. Select "Circle" on the Features Menu. Position the cursor on the Message field and type "MEASURE REAR .375 HOLE". Press "Enter".
4. Take a minimum of 3 hits on the hole. Press "Done". The results will appear on the Print Preview screen.

 

5. On the Print Preview screen go to "Format" and select "True Position MMC".
6. Select the Label field with the cursor and press “Enter”. Type "REAR.375 BOLT HOLE".
7.  Enter the nominal values. Place the cursor on the value you wish to change and press “Enter”. Type the new value and press “Enter”. Repeat for each value you wish to change.

Enter the following nominal values:

 

X ‑ 0.0000

Y ‑ 1.0000

D ‑ 0.3750

D UPPER TOL 0.005

D LOWER TOL ‑0.005

TRUE POS TOL 0.0100

 

8. Since the next measurement is also a "Circle", select "More" on the softkeys.

 

Right and Bottom Bolt Holes

Measure the right bolt circle of the demo part.

 

 

1. Position the cursor on the Message field and type "MEASURE RIGHT.375 HOLE". Press "Enter".
2. Take a minimum of 3 hits on the hole. Press "Done".
3. On the Print Preview screen enter the label "RIGHT .375 BOLT HOLE".
4. Enter the following nominal values:

 

X ‑ 1.0000

Y ‑ 0.0000

D ‑ 0.3750

UPPER TOL 0.005

LOWER TOL ‑0.005

TRUE POS UPPER TOL 0.0100

 

 

5. Select the "More" softkey at the bottom of the screen to measure another circle feature without returning to the Main Menu.

 

 

6. Position the cursor on the Message field and type"MEASURE BOTTOM.375 HOLE". Press "Enter".
7. Measure the bottom bolt hole with a minimum of 3 hits. Press "Done".

 

8. On the Print Peview screen enter the label "BOT­TOM .375 BOLT HOLE" and the following nominal values:

 

X ‑ 0.0000

Y ‑ ‑1.0000

D ‑ 0.3750

UPPER TOL 0.005

LOWER TOL ‑0.005

TRUE POS TOL 0.0100

 

 

 

9. Press "Done".

 

Translate Origin to Counterbore

Remeasure the counterbore so that the origin can be trans­lated from the center bolt hole back to the counterbore.

 

 

 

1. Select “Measurements” on the Main Menu.
2. Select "Circle" on the Features Menu.
3. Position the cursor on the Message field and type "MEASURE CENTER COUNTERBORE". Press "Enter".
4. Take a minimum of 3 hits within the counterbore. Press "Done".

 

 

Since this feature is being measured only as a means of translating the origin, we do not need the measurement results. On the Print Preview screen position the cursor to "Printer" and change the option to "No".

 

1.      On the Print Preview screen select "Done".

 

 

2.      Select "Translate/Rotate" on the Alignments Menu.

3.      Select "Translate to “Last" on the Translate/ Rotate screen. Press "Done".

 

 

Slot Measurement

Measure the slot on the left side of the demo part.

 

 

1. Select “Measurements” on the Main Menu.
2. Select "Slot" on the Features Menu.
3. Position the cursor on the Message field and type 'TOP OF SLOT, BOTTOM OF SLOT". Press "Enter".
4. Take a minimum of 3 hits on the rear semi‑circle of the slot. Be sure to move the probe away from the slot wall, toward the center of the slot, before remov­ing the probe. Press "Done".

 

 

5. Take a minimum of 3 hits on the front semi‑circle of the slot. Press "Done".
6. On the Print Preview screen enter the label "SLOT" and the following values:

 

Printer: Yes

Format: Full Display

Nominals/Tolerances

 

Nominal      Up +Tol       Lwr ‑Tol

X ‑ 2.07         .005           .005

Y ‑ .1275       .005           .005

R ‑ .75           .010           .010 (Slot width)

D ‑ 2.38         .004            .004 (Slot length)

 

             Press “Done”.

 

 

 

Circle‑Circle Distance

Measure the rear left circle and the front left circle to calculate        the distance between them.

 

 

1. Select "2-D Distances" on the Main Menu.
2. Select "Circle/Circle" on the Distances Menu.
3. Position the cursor on the Message field and type "LEFT REAR 1" HOLE, LEFT FRONT 1" HOLE". Press "Enter".
4. Measure the left rear circle taking a minimum of 3 hits. Press "Done".
5. Measure the left front circle taking a minimum of 3 hits. Press "Done".

 

 

6. On the Print Preview screen enter the label "2 LEFT 1" HOLES‑DISTANCE" and the following nominal values:

 

D Nominal ‑ 2.00

UPPER TOL 0.002

LOWER TOL ‑0.003

 

The results of the "Circle‑Circle Distance" measure­ment will appear on the Print Preview screen and will print on the printer.

 

 

 

7. Select the "More" softkey at the bottom of the screen to measure another "Circle‑Circle Distance" feature without returning to the Main Menu.

 

 

8. Position the cursor on the Message field and type "BOTTOM.375 HOLE, TOP.375 HOLE". Press "Enter".

 

 

9. Measure the bottom bolt hole of the bolt circle group taking a minimum of 3 hits. Press "Done".

 

10. Measure the top bolt hole of the bolt circle group taking a minimum of 3 hits. Press "Done".

 

 

11. On the Print Preview screen enter the label "2 RIGHT.375 HOLES‑DISTANCE". Notice that the nominal and tolerance values are correct from the previous distance. The results of the "Circle‑Circle Distance" measurement will appear on the Print Preview screen. Press "Done".

 

Line-Line Angle

Measure the left rear angle and the rear surface to calculate the angle between them.

 

 

1. Select "Angles" on the Main Menu.
2. Select "Line/Line" from the Angles Menu.
3. Position the cursor on the Message field and type "LEFT REAR ANGLE‑REAR SURFACE". Press"Enter".

 

 

4. Take 2 hits on the angle for the first line. Take the first hit on the left end of the angle and the second hit on the right end of the angle. Press "Done".
5. Take 2 more hits on the rear surface. Take the first hit on the left end of the rear plane and the second hit on the right end. Press "Done". The program will now construct the angle between the lines.

6. On the Print Preview screen enter the label "ANGLE AT REAR" and the following values:

            ANGLE Nominal –16.000

            UPPER TOL .2

            LOWER TOL -.2

 

 

 

Perpendicular Plane‑Plane

Measure the top plane (surface) and the front plane to calcu­late their perpendicularity to each other.

 

 

1. Select "Orientation" from the Main Menu.
2. Select "Perp: Plane/Plane" from the Orientation Menu.
3. Position the cursor on the Message field and type "MEASURE TOP SURFACE THEN FRONT SURFACE". Press "Enter".
4. Measure the top plane of the demo part with 3 hits randomly spaced. Press "Done".

 

 

 

5. Measure the front plane with 3 hits randomly spaced. Press "Done". The program will now cal­culate the perpendicularity.
6. On the Print Preview screen enter the label "PER­PENDICULARITY:TOP & FRONT SURFACES". Enter the following nominal values:

 

D Nominal ‑0

UPPER TOL 0.01

LOWER TOL 0

 

7. Press "Done".

 

 

 

 

 

 

Name ___________________________           Date _____________________________

 

 

            Part # PS3B

            Part Desc: Measurement

            Quantity Req.: 1

 

 

PLEASE HAVE INSTRUCTOR INITIAL AND DATE AFTER REQUIRED OPERATIONS

 

                                                                                                            Instructor

Step #                        Location                   Description                          Initials                    Date       

 

10                     Student                         Follow the Measurement Tutorial.

 

20                     CMM                            Staple the CMM Printouts to this page.

 

30                     Instructor                       Turn into instructor.