A bench vise should only be used when it's mounted securely in place to avoid unintended releases that may occur when it slips or rotates out of position. Use care not to over-tighten the knobs to prevent damaging material you are working with, keep protective elements in place during use to prevent injury from cuts/pinches, always engage the secondary safety mechanism if available before tightening down material being clamped, check all bolts regularly for tightness.