I made this jig to adjust the drill press table perpendicular to the quill.
A dial indicator is bolted to the jig and it is chucked into the drill press. Zero the indicator on one side of the table. Next, rotate the chuck by hand and check the other side. If the table is perfectly adjusted, the indicator will remain at zero. If an adjustment is needed, move the table half the difference, zero the indicator, and check again. The table can also be checked front to rear, but usually this can only be adjusted with shims.