recipe / good to have :
... 0 dial gauge ( image 01 )
... length caliber ( image 02 )
... maybe ( precision ) level ( image 03 )
if something missing, just use your imagination
one more thing : inspect "stuff" so to be aware of target precision :
... 0 dial gauge; check :
...... accuracy when showing "real distance", when armed at 0
...... repetability
...... paralelism between frontals
... length caliber; check :
...... paralelism between frontals
...... it's length
... ( precision ) level : put it on something
if all ok, than, after editing parameters, errors for expected distances should be < 0.03
ps : some guys&girls always / regulary inspects their measurements instruments, thus this becames routine for them; me ?