How do I put a vise on the mill?

First, make sure the table is clear of chips. Then, gently place the vise on top of the table and use a wrench to tighten one of the bolts that fits into the grooves of the table.

To make sure the vise is straight, place a dial indicator along the edge of the jaw. When you move the table left and right in the x direction, the dial indicator should not change. If it does, lightly tap the vise side of the vise with a mallet to angle it correctly, and then tighten the second bolt. Read here for a step-by-step approach.