I am new to CNC and New to Mach3

I am face milling a part .030" from the top of my vise. What I have been doing is using a brass .030" feeler gauge between the top of the vise and the face mill tooth. Zero axis lower the table .315" ( this is the Max depth cut last pass) then reset the axis to Zero. Is there a way just to enter .315" in the DRO and making it accept that value?

I know I am missing something, just cannot seem to find how to do it.

Thanks.

Ark1

TonyK.