Test the natural deflection of cast iron ruler

Support the ruler with equal height blocks at the standard support marks 2L/9 from both ends of the ruler and place it on the reference plane. Use an indicator or comparator with a scale of 0.001mm to measure the reading in the middle of the working face length; Then move the height block to the support distance position (at both ends of the ruler), stabilize for 10 minutes, and read it with an indicator or comparator; The difference Y between two readings is the natural deflection of the ruler.