Checking the height of center of a tooling plate
1. Sweep across the top of a pin in the spindle.
2.Use gauge blocks to find the height.

If you used a 1/2" pin with a slide that has 1/2" center, you should find the top of pin at .7500".
Be sure to measure the pin accurately and check that it runs concentric with the spindle. If the pin is off, your height of center will be, as well.

If the gauge blocks find zero at .752" then you know your slide is .002" too low.