Checking SMR Runout and Depth Error
SMR Runout & Depth Error Field Check
See the linked diagrams in document 06 REF177-137.
Overview
This procedure outlines the steps required to check the Spherically Mounted Retroreflector (SMR) for runout and depth error using the FARO® Laser Tracker and Measure. An experienced operator can perform this check in approximately one half hour.
The SMR was designed to be a Laser Tracker System accessory not requiring adjustment in use. However, in case the SMR is dropped or sustains an impact, there may be a need to check its proper operation and performance.
Note: This procedure is a field check and does not check the runout and depth errors to the same accuracy as FARO’s certification process.
Equipment
- FARO Laser Tracker and Support Equipment
- Heavy-Duty Nest
- SMR
Procedure
Setup
Setup, power-up, and Startup the tracker on a stable stand per the instructions in the Operators Manual.
Preparation
- Glue the heavy-duty nest to a wall, an instrument stand, or any surface that is highly stable. The nest should be between 1 and 2 meters from the tracker.
- Open Measure and connect to the Laser Tracker.
- Select Millimeters as the units for the current file.
- Go to Devices > Laser Tracker > Set Distance Mode
- If tracker has the option to measure with an Interferometer, set the tracker to IFM Only mode; else set to ADM mode.
- Click OK to exit.
- Go to Devices > Hardware Config and change the Samples per Measurement to 3000. Click OK to exit.
- Place the SMR in the Home position (a.k.a. TMR – Tracker Mounted Reset) and use Devices > Laser Tracker > Reset or the “T” Hotkey to have the laser tracker reset to Home position.
- Go to Devices > Laser Tracker > Operational Checks. Go to the Repeatability tab on this page and run a Static Repeatability Operational Check on the heavy-duty nest to be used for the test. The Static Repeatability should be < 0.010 mm. If the Total is greater than 0.010 mm, inspect the stands and the environment for sources of poor repeatability.
Runout Check
- Place the SMR in the TMR and use Devices > Laser Tracker > Reset or the “T” Hotkey to have the laser tracker go to Home position.
- Track the SMR to the heavy-duty nest.
- Once the SMR is on the heavy-duty nest, ensure the SMR serial number on the outer surface of the SMR “can” is up.
- Go to Measure > Point > Comp Off and press the Insert key on the keyboard to measure. When the Tracker has finished measuring this point, press the Home key on the keyboard and then press the Enter key to complete the measurement.
- Rotate SMR approximately 45o clockwise about the axis of the laser beam, and repeat Step (3) to take another measurement.
- Repeat Steps (3) and (4) seven more times for a total of nine observations.
- The last observation will be taken with the SMR in the same position it was when the first observation was taken.
- Save the Measure drawing file (.sat extension) in a convenient location on the computer and continue with the depth error check below.
Depth Error Check
- Place the SMR in the TMR and use Devices > Laser Tracker > Reset or the “T” Hotkey to have the laser tracker go to Home position.
- Track the SMR to the heavy-duty nest:
- Once the SMR is on the heavy-duty nest, ensure the SMR serial number on the outer surface of the SMR “can” is up and the SMR is pointed straight at the Tracker.
- Go to Measure > Point > Comp Off and press the Insert key on the keyboard to measure. When the Tracker has finished measuring this point, press the Home key on the keyboard and then press the Enter key to complete the measurement.
- Rotate SMR approximately 20o about an axis perpendicular to the axis of the laser beam and take a Comp Off measurement.
- Rotate SMR approximately 20o about an axis perpendicular to the axis of the laser beam in the direction opposite to that of Step (4). Take a Comp Off measurement with the SMR in that position.
- Take Comp Off measurements with SMR pointing 20 degrees up or down.
- If the SMR is mounted on a wall or column, you can measure points in both orientations. When mounted on a drift nest as shown in the picture, the only option is the up position.
- Save the drawing file again and precede with the evaluation of the data gathered as directed below.
Evaluate the Runout and Depth Error Field Check Results
- In Measure, go to Construct > Point > Best Fit. Select the 9 points you measured during the runout field check and then click OK.
- Again, go to Construct > Point > Best Fit. (The Enter key will recall this command without going back through the menus). Select the 3 or 4 points you measured during the depth error field check and click OK.
- Go to File > Review Features and highlight the first point you just constructed in the Select Feature window.
- Check that the following criterion is true on the review tab for the constructed point:
Form < 0.0127 mm
- Check that the following criterion is true on the review tab for the constructed point:
- If the criterion in Step (3) is met, the SMR was field checked to have a runout that is in spec.
- If the criterion in Step (3) is not met, the SMR was field checked to have a runout that is out of spec.
- Go to File > Review Features and highlight the second point you constructed in the Select Feature window.
- Check that the following criterion is true on the review tab for the constructed point:
Form < 0.0127 mm
- Check that the following criterion is true on the review tab for the constructed point:
- If the criterion in Step (6) is met, the SMR was field checked to have a depth error that is in spec.
- If the criterion in Step (6) is not met, the SMR was field checked to have a depth error that is out of spec.
Contact FARO Technologies regarding SMR’s that fail this field-test.
Keywords:
runout, SMR, Tracker, Depth Error, smr runout