421/521 Lab 5

Total Station, Laser Tracker and Coordinate Measuring Machine CMM

Motivation

• Become familiar with three types of precision 3D measuring devices

• Not to become experts, but to be aware of their existence and their potential to solve problems

• To large extent computers make these instruments useful to the common person

• They can be lifesavers in certain situations– Total stations and laser trackers can be leased– Can buy time on a CMM, or contract inspection

Total station• Read instructions• Go through set up • Measure length of a ruler at end of lab• Measure distance to ruler with tape measure• Does math make sense? Don’t believe any

measurement with a new instrument• Try measuring size of light fixture

– Does the math rectify the shape?

Laser tracker

• Get help from the TA or knowledgeable user• These are very expensive instruments• Use the LT to measure some of the same

features measured with the total station• How do the two sets of measurements compare?• Which measurements are more precise, axial or

lateral (azimuthal)? Why?

More fun with the TS

• Set the TS up outside behind the East Wing• There is a bench mark in the sidewalk to the

garage• Measure some features of the buildings visible• Check that dimensions make sense by

measuring a brick• Pick a easily identified point and do a reversal

– Do you get the same answer both times?– This is the classic check of a theodolite or transit

CMM

• Go through start up check list– Marco made up a nice couple pages on this– He is out but I will get this on-line asap

• Follow through with the measurement of the Master ball to establish the machine coordinate system

• Measure several artifacts and use the software to see the best fit shape

Important

• All the instruments are very expensive– Little to no money to fix them if broken– Money earning projects rely on the CMM and LT

• Do not force anything, move slowly and deliberately. Don’t drop anything

• Think about each step before making a move• The CMM probe tip is very delicate, move up to

work slowly and gently